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  • 1. Aguirre, Miren
    et al.
    Johansson Salazar-Sandoval, Eric
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. SP Technical Research Institute of Sweden, Sweden.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ahniyaz, Anwar
    Paulis, Maria
    Ramon Leiza, Jose
    Hybrid acrylic/CeO2 nanocomposites using hydrophilic, spherical and high aspect ratio CeO2 nanoparticles2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 47, s. 20280-20287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dispersion of CeO2 nanoparticles and nanorods stabilized with nitrilotriacetic acid (NTA) and a 4,4'-azobis(4-cyanovaleric acid) (V-501) initiator has been used to initiate the emulsion polymerization of acrylic monomers, yielding stable hybrid CeO2 nanoparticle-nanorod/polyacrylate latexes for the first time. Films cast from these hybrid latexes are transparent due to the very homogenous distribution of the polymer compatibilized CeO2. Furthermore, it has been proven that the UV-Vis absorption capacity of the hybrid latexes is enhanced with the incorporation of the nanorods.

  • 2. Araujo, Rafael B.
    et al.
    Banerjee, Amitava
    Panigrahi, Puspamitra
    Yang, Li
    Stromme, Maria
    Sjodin, Martin
    Araujo, C. Moyses
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala University, Sweden.
    Designing strategies to tune reduction potential of organic molecules for sustainable high capacity battery application2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 9, s. 4430-4454Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic compounds evolve as a promising alternative to currently used inorganic materials in rechargeable batteries due to their low-cost, environmental friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of the density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, and pi bonds, as well as carboxyl groups on the formal potential, have been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.

  • 3. Araujo, Rafael B.
    et al.
    Islam, M. S.
    Chakraborty, Sudip
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Predicting electrochemical properties and ionic diffusion in Na2+2xMn2-x(SO4)(3): crafting a promising high voltage cathode material2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 2, s. 451-457Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sodium ion batteries have emerged as a good alternative to lithium based systems due to their low cost of production. In this scenario, the search for higher voltage, sodium cathodes results in a new promising alluaudite structure Na2+2xMn2-x(SO4)(3). The structural, electronic and Na diffusion properties along with defects have been reported in this investigation within the framework of density functional theory. A band gap of 3.61 eV has been computed and the average deintercalation potential is determined to be 4.11 V vs. Na/Na+. A low concentration of anti-site defects is predicted due to their high formation energy. The biggest issue for the ionic diffusion in the Na2+2xMn2-x(SO4)(3) crystal structure is revealed to be the effect of Mn vacancies increasing the activation energy of Na+ ions that hop along the [001] equilibrium positions. This effect leads to activation energies of almost the same high values for the ionic hop through the [010] direction characterizing a 2D like ionic diffusion mechanism in this system.

  • 4. Aung, S. H.
    et al.
    Zhao, L.
    Nonomura, K.
    Oo, T. Z.
    Zakeeruddin, S. M.
    Vlachopoulos, N.
    Sloboda, Tamara
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Svanström, S.
    Cappel, Ute B.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Hagfeldt, A.
    Grätzel, M.
    Toward an alternative approach for the preparation of low-temperature titanium dioxide blocking underlayers for perovskite solar cells2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 17, s. 10729-10738Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The anodic electrodeposition method is investigated as an alternative technique for the preparation of a titanium oxide (TiO 2 ) blocking underlayer (UL) for perovskite solar cells (PSCs). Extremely thin Ti IV -based films are grown from aqueous acidic titanium(iii) chloride in an electrochemical cell at room temperature. This precursor layer is converted to the UL (ED-UL), in a suitable state for PSC applications, by undertaking a sintering step at 450 °C for half an hour. PSCs with the composition of the light-absorbing material FA 0.85 MA 0.10 Cs 0.05 Pb(I 0.87 Br 0.13 ) 3 (FA and MA denote the formamidinium and methylammonium cations, respectively) based on the ED-UL are compared with PSCs with the UL of a standard type prepared by the spray-pyrolysis method at 450 °C from titanium diisopropoxide bis(acetylacetonate) (SP-UL). We obtain power conversion efficiencies (PCEs) of over 20% for mesoscopic perovskite devices employing both ED-ULs and SP-ULs. Slightly higher fill factor values are observed for ED-UL-based devices. In addition, ED-ULs prepared by the same method have also been applied in planar PSCs, resulting in a PCE exceeding 17%, which is comparable to that for similar PSCs with an SP-UL. The preparation of ED-ULs with a lower sintering temperature, 150 °C, has also been examined. The efficiency of a planar PSC incorporating this underlayer was 14%. These results point out to the possibility of applying ED-ULs in flexible planar PSCs in the future.

  • 5. Banerjee, Amitava
    et al.
    Araujo, Rafael B.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala University, Sweden.
    Unveiling the thermodynamic and kinetic properties of NaxFe(SO4)(2) (x=0-2): toward a high-capacity and low-cost cathode material2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 46, s. 17960-17969Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mineral eldfellite, NaFe(SO4)(2), was recently proposed as an inexpensive candidate for the next generation of cathode application in Na-based batteries. Employing the density functional theory framework, we have investigated the phase stability, electrochemical properties and ionic diffusion of this eldfellite cathode material. We showed that the crystal structure undergoes a volume shrinkage of approximate to 8% upon full removal of Na ions with no imaginary frequencies at the Gamma point of phonon dispersion. This evokes the stability of the host structure. According to this result, we proposed structural changes to get higher specific energy by inserting two Na ions per redox-active metal. Our calculations indicate NaV(SO4)(2) as the best candidate with the capability of reversibly inserting two Na ions per redox center and producing an excellent specific energy. The main bottleneck for the application of eldfellite as a cathode is the high activation energies for the Na+ ion hop, which can reach values even higher than 1 eV for the charged state. This effect produces a low ionic insertion rate.

  • 6. Banerjee, Amitava
    et al.
    Chakraborty, Sudip
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala University, Sweden.
    Bromination-induced stability enhancement with a multivalley optical response signature in guanidinium [C(NH2)(3)](+)-based hybrid perovskite solar cells2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 35, s. 18561-18568Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Guanidinium lead iodide (GAPbI(3)) has been synthesized experimentally, but stability remains an issue, which can be modulated by the insertion of bromine (Br) into the system. We have performed a systematic theoretical investigation to see how bromination can tune the stability of GAPbI(3). The optical properties were also determined, and we have found formation enthalpy-based stability in the perovskite systems, which are active in the visible and IR region even after bromine insertion and additionally more active in the IR range with the transition from GAPbI(3) to GAPbBr(3). The spin orbit coupling effect is considered throughout the band structure calculations. The ensemble of the primary and secondary gaps in the half and fully brominated hybrid perovskites leads to the phenomenon of a multipeak response in the optical spectra, which can be subsequently attributed as multivalley optical response behaviour. This multivalley optical behaviour enables the brominated guanidinium-based hybrid perovskites to exhibit broad light harvesting abilities, and this can be perceived as an idea for natural multi-junction solar cells.

  • 7.
    Cong, Jiayan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Kinschel, Dominik
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. Dyenamo AB, Sweden.
    Daniel, Quentin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Safdari, Majid
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Gabrielsson, E.
    Chen, Hong
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Svensson, Per H.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. SP Process Development Forskargatan, Sweden.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian University of Technology (DUT), China.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Bis(1,1-bis(2-pyridyl)ethane)copper(i/II) as an efficient redox couple for liquid dye-sensitized solar cells2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 38, s. 14550-14554Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new redox couple, [Cu(bpye)2]+/2+, has been synthesized, and applied in dye-sensitized solar cells (DSSCs). Overall efficiencies of 9.0% at 1 sun and 9.9% at 0.5 sun were obtained, which are considerably higher than those obtained for cells containing the reference redox couple, [Co(bpy)3]2+/3+. These results represent a record for copper-based complex redox systems in liquid DSSCs. Fast dye regeneration, sluggish recombination loss processes, faster electron self-exchange reactions and suitable redox potentials are the main reasons for the observed increase in efficiency. In particular, the main disadvantage of cobalt complex-based redox couples, charge-transport problems, appears to be resolved by a change to copper complex redox couples. The results make copper complex-based redox couples very promising for further development of highly efficient DSSCs.

  • 8. Dowland, Simon A.
    et al.
    Reynolds, Luke X.
    MacLachlan, Andrew
    Cappel, Ute B.
    Haque, Saif A.
    Photoinduced electron and hole transfer in CdS:P3HT nanocomposite films: effect of nanomorphology on charge separation yield and solar cell performance2013Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 1, nr 44, s. 13896-13901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of morphology on the photophysical properties of blend films containing in situ grown CdS and poly(3-hexylthiophene-2,5-diyl) (P3HT), fabricated utilising a metal xanthate single source precursor, is reported. A combination of transient absorption spectroscopy (TAS), transmission electron microscopy (TEM) and photovoltaic device measurements are employed to study the relationship between the efficiency of charge separation, photocurrent generation and thin film morphology. We identify that a significant proportion of the extractable charge originates from the direct excitation of CdS followed by hole-transfer to the P3HT polymer. The yield of this hole-transfer step from the inorganic CdS to the organic polymer is largely unaffected by the film’s nanomorphology, while the dissociation of P3HT excitons into free charges at the CdS:P3HT interface is found to be strongly dependent on this parameter with high yields of charge transfer only being achieved at high CdS loadings. The present study elucidates design rules for the optimization of hybrid inorganic-organic solar energy conversion devices.

  • 9.
    Erlandsson, Johan
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Fiberteknologi.
    Pettersson, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Ingverud, Tobias
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Granberg, H.
    Larsson, Per A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Malkoch, Michael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Wågberg, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    On the mechanism behind freezing-induced chemical crosslinking in ice-templated cellulose nanofibril aerogels2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 40, s. 19371-19380Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The underlying mechanism related to freezing-induced crosslinking of aldehyde-containing cellulose nanofibrils (CNFs) has been investigated, and the critical parameters behind this process have been identified. The aldehydes introduced by periodate oxidation allows for formation of hemiacetal bonds between the CNFs provided the fibrils are in sufficiently close contact before the water is removed. This is achieved during the freezing process where the cellulose components are initially separated, and the growth of ice crystals forces the CNFs to come into contact in the thin lamellae between the ice crystals. The crosslinked 3-D structure of the CNFs can subsequently be dried under ambient conditions after solvent exchange and still maintain a remarkably low density of 35 kg m-3, i.e. a porosity greater than 98%. A lower critical amount of aldehydes, 0.6 mmol g-1, was found necessary in order to generate a crosslinked 3-D CNF structure of sufficient strength not to collapse during the ambient drying. The chemical stability of the 3-D structure can be further enhanced by converting the hemiacetals to acetals by treatment with an alcohol under acidic conditions.

  • 10.
    Ihrner, Niklas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi.
    Johannisson, Wilhelm
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Sieland, Fabian
    University of Paderborn, Faculty of Science, Department of Chemistry, Paderborn, Germany .
    Zenkert, Dan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Structural lithium ion battery electrolytes via reaction induced phase-separation2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 48, s. 25652-25659Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For the realization of structural batteries, electrolytes where both higher ionic conductivity and stiffness are combined need to be developed. The present study describes the formation of a structural battery electrolyte (SBE) as a two phase system using reaction induced phase separation. A liquid electrolyte phase is combined with a stiff vinyl ester based thermoset matrix to form a SBE. The effect of monomer structure variations on the formed morphology and electrochemical and mechanical performance has been investigated. An ionic conductivity of 1.5 x 10(-4) S cm(-1), with a corresponding storage modulus (E') of 750 MPa, has been obtained under ambient conditions. The SBEs have been combined with carbon fibers to form a composite lamina and evaluated as a battery half-cell. Studies on the lamina revealed that both mechanical load transfer and ion transport are allowed between the carbon fibers and the electrolyte. These results pave the way for the preparation of structural batteries using carbon fibers as electrodes.

  • 11. Jiang, Xiaoqing
    et al.
    Yu, Ze
    Li, Hai-Bei
    Zhao, Yawei
    Qu, Jishuang
    Lai, Jianbo
    Ma, Wanying
    Wang, Dongping
    Yang, Xichuan
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    A solution-processable copper(II) phthalocyanine derivative as a dopant-free hole-transporting material for efficient and stable carbon counter electrode-based perovskite solar cells2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 34, s. 17862-17866Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A solution-processable copper(II) phthalocyanine derivative coded as CuPc-TIPS has been synthesized and adopted as a hole-transporting material (HTM) in perovskite solar cells (PSCs), in combination with a mixed-ion perovskite absorber and a low-cost carbon cathode. Optimised PSC devices based on pristine CuPc-TIPS without any additives or dopants show a decent power conversion efficiency of 14.0% (measured at 100 mW cm(-2) illumination, AM 1.5G), together with a good long-termstability under ambient conditions. The present finding highlights the potential of solution-processed copper phthalocyanine derivative-based HTMs for the development of efficient and stable PSCs in the future.

  • 12. Li, Xing
    et al.
    Xu, Bo
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Liu, Peng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Hu, Yue
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Hua, Jianli
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Tian, He
    Molecular engineering of D-A-pi-A sensitizers for highly efficient solid-state dye-sensitized solar cells2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 7, s. 3157-3166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two newquinoxaline-based D-A-pi-A organic sensitizers AQ309 and AQ310 have been designed and synthesized employing 3,4-ethylenedioxythiophene (EDOT) and cyclopentadithiophene (CPDT) as plinker units, respectively. The new AQ309 and AQ310 dyes have been applied in all-solid-state dye-sensitized solar cells (ssDSSCs). An impressive record photoelectric conversion efficiency (PCE) of 8.0% for AQ310-based ssDSSCs using Spiro-OMeTAD as the hole transport material (HTM) was obtained under standard AM 1.5 (100 mW cm (2)) solar intensity. This clearly outperforms the PCE of the state-of-theart organic D-pi-A dye LEG4-based devices showing a PCE of 7.3% under the same conditions. Moreover, an excellent high PCE of 8.6% was also recorded for AQ310-based devices under 50% solar intensity. Meanwhile, the AQ310-based ssDSSCs showed a much longer electron lifetime according to the transient photovoltage decay measurement, demonstrating lower charge recombination losses in the devices. Photo-induced absorption spectroscopy (PIA) indicated that AQ310 could be more efficiently regenerated by Spiro-OMeTAD. These results show that molecular engineering is a promising strategy to develop D-A-pi-A organic sensitizers for highly efficient ssDSSCs.

  • 13. Li, Yuanyuan
    et al.
    Yang, Xuan
    Fu, Qiliang
    Rojas, Ramiro
    Yan, Max
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Berglund, Lars
    Towards centimeter thick transparent wood through interface manipulation2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 3, s. 1094-1101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transparent wood is an attractive structural material for energy-saving buildings due to its high optical transmittance, good thermal insulation, and high toughness. However, thick highly transparent wood is challenging to realize. In the current work, highly transparent wood (1.5 mm) with a transmittance of 92%, close to that of pure PMMA (95%), is demonstrated. The high transmittance was realized by interface manipulation through acetylation of wood template. Both experiments and electromagnetic modeling support that the improved transmittance is mainly due to elimination of interface debonding gap. By applying this method, a centimeter-thick transparent wood structure was obtained. The transparent wood could be used as a substrate for an optically tunable window by laminating a polymer dispersed liquid crystal (PDLC) film on top. The techniques demonstrated are a step towards the replacement of glass in smart windows and smart buildings.

  • 14.
    Liu, Dongming
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wu, Qiong
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Andersson, Richard L.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Farris, Stefano
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Cellulose nanofibril core-shell silica coatings and their conversion into thermally stable nanotube aerogels2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 30, s. 15745-15754Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A facile water-based one-pot reaction protocol for obtaining 20 nm thick uniform silica coatings on cellulose nanofibrils (CNFs) is herein presented for the first time. The fully covering silica shells result in the thermal stability of the CNFs improved by ca. 70 degrees C and 50 degrees C under nitrogen and oxygen atmospheres, respectively. Heating of the core-shell hybrid fibres to 400 degrees C results in complete degradation/removal of the CNF cores, and demonstrates an inexpensive route to large-scale preparation of silica nanotubes with the CNFs used as templates. The key to a uniform condensation of silica (from tetraethyl orthosilicate) to cellulose is a reaction medium that permits in situ nucleation and growth of the silica phase on the fibrils, while simultaneously matching the quantity of the condensed silica with the specific surface area of the CNFs. Most coatings were applied to bundles of 2-3 associated CNFs, which could be discerned from their negative imprint that remained inside the silica nanotubes. Finally, it is demonstrated that the coated nanofibrils can be freeze-dried into highly porous silica/cellulose aerogels with a density of 0.005 g cm(-3) and how these hybrid aerogels preserve their shape when extensively exposed to 400 degrees C in air (>6 h). The resulting material is the first reported silica nanotube aerogel obtained by using cellulose nanofibrils as templates.

  • 15. Liu, Jinxuan
    et al.
    Zhou, Wencai
    Liu, Jianxi
    Fujimori, Yamato
    Higashino, Tomohiro
    Imahori, Hiroshi
    Jiang, Xue
    Zhao, Jijun
    Sakurai, Tsuneaki
    Hattori, Yusuke
    Matsuda, Wakana
    Seki, Shu
    Garlapati, Suresh Kumar
    Dasgupta, Subho
    Redel, Engelbert
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Woll, Christof
    A new class of epitaxial porphyrin metal-organic framework thin films with extremely high photocarrier generation efficiency: promising materials for all-solid-state solar cells2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 33, s. 12739-12747Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate the fabrication of a new class of epitaxial porphyrin metal-organic framework thin films whose photophysical properties can be tuned by the introduction of electron-donating diphenylamine (DPA) groups into the porphyrin skeleton. The attachment of DPA groups results in strongly improved absorption characteristics, yielding the highest photocarrier generation efficiency reported so far. DFT calculations identify a shift of the charge localization pattern in the VBM (lowest unoccupied molecular orbital), confirming that the introduction of the DPA groups is the main reason for the shift of the optical absorption spectrum and the improved photocurrent generation.

  • 16.
    Liu, Peng
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Xu, Bo
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Karlsson, Karl Martin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Zhang, Jinbao
    Vlachopoulos, Nick
    Boschloo, Gerrit
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    The combination of a new organic D-pi-A dye with different organic hole-transport materials for efficient solid-state dye-sensitized solar cells2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 8, s. 4420-4427Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new organic donor-pi-acceptor sensitizer MKA253 has been applied for highly efficient solid-state dye-sensitized solar cells (ssDSSCs). Using 2,2',7,7'-tetrakis(N,N-di-pi-methoxyphenyl-amine) 9,9'-spirobifluorene (Spiro-OMeTAD) as the hole transport material (HTM), an excellent power conversion efficiency of 6.1% was recorded together with a high short-circuit current of 12.4 mA cm(-2) under standard AM 1.5G illumination (100 mW cm(-2)). Different combinations of dyes and HTMs have also been investigated in the ssDSSC device. The results showed that small molecule HTM based devices suffer from comparably high electron recombination losses, thus causing low open-circuit voltage. In addition, photo-induced absorption (PIA) spectroscopy showed that the small-molecule HTMs lead to more efficient dye regeneration in comparison with Spiro-OMeTAD, despite a lower thermodynamic driving force. The results of this study also show that optimized energy levels for the dye-HTMs could be a vital factor for highly efficient ssDSSCs.

  • 17. Meng, Peng
    et al.
    Wang, Mei
    Yang, Yong
    Zhang, Shuai
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian Univ Technol, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, China.
    CdSe quantum dots/molecular cobalt catalyst co-grafted open porous NiO film as a photocathode for visible light driven H-2 evolution from neutral water2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 37, s. 18852-18859Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An active noble-metal-free photocathode was fabricated by co-grafting water-soluble thioglycolic acid-stabilized CdSe quantum dots and a molecular cobaloxime catalyst (CoP) through chemical linkage on a p-type open porous NiO film. This photocathode was used as a working electrode in a three-electrode cell, which displayed a photocurrent density up to 110 mu A cm(-2) at an applied potential of 0 V vs. NHE in 0.1 M Na2SO4 solution at pH 6.8 upon visible light illumination. The comparative studies showed that the open porous NiO/CdSe electrode did display a higher photocurrent density than that exhibited by an analogous planar NiO/CdSe electrode made by doctor-blading a NiO paste. Long-time photoelectrolysis experiments revealed that about 83% of the photocurrent density remained after 3.5 h illumination at 0.2 V vs. NHE. The open porous NiO/CdSe/CoP photocathode showed a considerably better current density and photocatalytic stability compared to the so-far reported dye-or QD-sensitized NiO cathodes with a cobaloxime catalyst chemically attached or physically adsorbed on the electrode surface under similar conditions.

  • 18.
    Pallon, L. K. H.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hoang, A. T.
    Pourrahimi, A. M.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Nilsson, Fritjof
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gubanski, S.
    Gedde, U. W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    The impact of MgO nanoparticle interface in ultra-insulating polyethylene nanocomposites for high voltage DC cables2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 22, s. 8590-8601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low density polyethylene (LDPE) nanocomposites with a reduced conductivity of two orders of magnitude are reported as a novel insulation material for high voltage distribution of renewable energy. The key to the high insulation capacity was to provide 70 nm hexagonal MgO nanoparticles with relatively tong, preferably 18 units long, hydrocarbon functional silsesquioxane coatings. This rendered the surface of the particles completely hydrophobic and also served as a protective layer against adsorption of polar low molecular weight atmospheric substances (H2O and CO2). The elimination of trace amounts of water, in combination with the provided carbon functionality, dramatically improved the dispersion of MgO nanoparticles. The lowest volume conductivity was ca. 7 x 10(-16) s m(-1) for 3 wt% surface coated nanoparticles. Extensive electron microscopy characterization was further used to relate the measured volume conductivity, acquired under conditions that resemble 800 kV high voltage direct current (HVDC) cables, to the distribution of the nanoparticles in the polymer matrix. The results show that an appropriate surface-modification approach yielded uniformly dispersed MgO nanoparticles up to contents as high as 9 wt%, with maintained 10-100 times reduced volume conductivity. Simulations of the MgO nanoparticles distribution revealed that the required interaction radius of the MgO-phase was 775 nm, setting a lower limit of particle amount to effectively work as electrical insulation promoters. The reduced volume conductivity values and scalable processing chemistry reported allow for the production of the next generation insulation material for HVDC cables.

  • 19.
    Pallon, Love K. H.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Liu, D.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hoang, A. T.
    Gubanski, S.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Formation and the structure of freeze-dried MgO nanoparticle foams and their electrical behaviour in polyethylene2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 14, s. 7523-7534Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrically insulating low-density polyethylene (LDPE) nanocomposites based on dispersed MgO nanoparticle foams are reported. The foams were obtained via freeze-drying aqueous suspensions of precipitated ca. 40 nm wide and 10 nm thick Mg(OH)(2) nanoparticles and dewatering (calcining) at 400 degrees C, resulting in a 25 times more voluminous powder compared to conventionally dried nanoparticles. This powder handling prior to extrusion melt-processing greatly facilitated the nanocomposite preparation since no particle grinding was necessary. Large quantities of particles were prepared (>5 g), and the nanoparticle foams showed improved dispersion in the LDPE matrix with 70% smaller aggregate sizes compared to the conventionally dried and ground nanopowders. The nature of the nanoparticle foams was evaluated in terms of their dispersion on Si-wafers using ultrasonication as a dispersing aid, which showed to be detrimental for the nanoparticle separation into solitary particles and induced severe aggregation of the calcined nanoparticles. The grind-free MgO nanoparticles/LDPE-composite was evaluated by electrical measurement. The prepared composite showed an initial ca. 1.5 orders of magnitude lower charging current at 10(2) s, and a 4.2 times lower charging current after 16 hours compared to unfilled LDPE. The results open a way for improved insulation to be implemented in the future high-voltage cable system and present a new promising nanoparticle powder handling technique that can be used on a large scale.

  • 20.
    Pourrahimi, A. M.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Liu, D.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ström, Valter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Heat treatment of ZnO nanoparticles: new methods to achieve high-purity nanoparticles for high-voltage applications2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 33, s. 17190-17200Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel methods based on orienting and coating of ZnO nanoparticles were studied in order to obtain uniform, nano-sized and ultra-pure ZnO grains/particles after heat treatment. A 1 nm zinc-hydroxy-salt complex layer on the nanoparticle surfaces was revealed by thermogravimetry and infrared spectroscopy. This 'phase' gradually decomposed into ZnO during the heat treatment while sintering occurred above 600 degrees C, as revealed by scanning-and transmission-electron microscopy. The c-axis alignment of the nanoparticles provided smaller pores than those associated with non-oriented nanoparticles, presenting the means to obtain high-density ceramics. The orientation resulted in a smaller grain size after heat treatment than that of the nonaligned nanoparticles. Another method that involved three steps - silane coating, heat treatment and silica layer etching - was used to remove the ionic species from the nanoparticle surface while preserving its hydroxylated surface. These ultra-pure nanoparticles are expected to be key components in the development of HVDC insulation polyethylene nanocomposites.

  • 21.
    Safdari, Majid
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Fischer, Andreas C.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Xu, Bo
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Kloo, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Erratum to: Structure and function relationships in alkylammonium lead(II) iodide solar cells2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 17, s. 9317-9317Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Safdari, Majid
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Fischer, Andreas I.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Xu, Bo
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Kloo, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Structure and function relationships in alkylammonium lead(II) iodide solar cells2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 17, s. 9201-9207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alkylammonium lead(ii) iodide materials (APbI<inf>3</inf>), based on the general formula of CH<inf>3</inf>-(CH<inf>2</inf>)<inf>n</inf>-NH<inf>3</inf>PbI<inf>3</inf>, may lead to a monumental leap in developing affordable photovoltaics. Herein, we correlate the structure and function relationships of alkylammonium lead(ii) iodide in solar cells. We investigated changes in the structure of APbI<inf>3</inf> materials by varying the alkylammonium cations in their structure. As the size of the alkylammonium cation increased, the crystallographic unit cell increased in size and yielded lower symmetry crystals. High symmetry materials, those with cubic symmetry, showed the highest conductivity, the smallest bandgap, and produced the best performing solar cells. Structural changes were investigated by X-ray crystallography, X-ray powder diffraction, and Raman scattering.

  • 23.
    Safdari, Majid
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Phuyal, D.
    Philippe, B.
    Svensson, Per H.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. SP Process Development, Sweden.
    Butorin, S. M.
    Kvashnina, K. O.
    Rensmo, H.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Impact of synthetic routes on the structural and physical properties of butyl-1,4-diammonium lead iodide semiconductors2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 23, s. 11730-11738Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the significant role of synthetic routes and the importance of solvents in the synthesis of organic-inorganic lead iodide materials. Through one route, the intercalation of dimethylformamide in the crystal structure was observed leading to a one-dimensional (1D) [NH3(CH2)4NH3]Pb2I6 structure of the product. This product was compared with the two-dimensional (2D) [NH3(CH2)4NH3]PbI4 recovered from aqueous solvent based synthesis with the same precursors. UV-visible absorption spectroscopy showed a red-shift of 0.1 eV for the band gap of the 1D network in relation to the 2D system. This shift primarily originates from a shift in the valence band edge as determined from photoelectron-and X-ray spectroscopy results. These findings also suggest the iodide 5p orbital as the principal component in the density of states in the valence band edge. Single crystal data show a change in the local coordination around iodide, while in both materials, lead atoms are surrounded by iodide atoms in octahedral units. The conductivity of the one-dimensional material ([NH3(CH2)4NH3]Pb2I6) was 50% of the two-dimensional material ([NH3(CH2)4NH3]PbI4). The fabricated solar cells reflect these changes in the chemical and electronic structure of both materials, although the total light conversion efficiencies of solar cells based on both products were similar.

  • 24.
    Safdari, Majid
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Phuyal, Dibya
    Philippe, Bertrand
    Svensson, Per H.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. SP Process Development, Sweden .
    Butorin, Sergei M.
    Kvashnina, Kristina O.
    Rensmo, Håkan
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Impact of Synthetic Route on Structural and Physical Properties of Butyl-1,4-Diammonium Lead Iodide Semiconductors2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488Artikkel i tidsskrift (Fagfellevurdert)
  • 25.
    Safdari, Majid
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Svensson, Per H.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. SP Process Development, Sweden.
    Hoang, Minh Tam
    Oh, Ilwhan
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Layered 2D alkyldiammonium lead iodide perovskites: synthesis, characterization, and use in solar cells2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 40, s. 15638-15646Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthetic route and properties of three 2D hybrid organic/inorganic lead iodide perovskite materials are reported. The 2D perovskites were synthesized from the reaction between PbI2 and the di-cations of 1,4-diaminobutane, 1,6-diaminohexane, and 1,8-diaminooctane. The resulting products were [NH3(CH2)(4)NH3] PbI4 (BdAPbI(4)), [NH3(CH2)(6)NH3]PbI4 (HdAPbI(4)), and [NH3(CH2)(8)NH3]PbI4 (OdAPbI(4)). Structural characterization shows that two dimensional perovskite structures were formed with inorganic structural planes separated by organic layers. Absorption spectra show band gaps of 2.37 eV (BdAPbI(4)), 2.44 eV (HdAPbI(4)), and 2.55 eV (OdAPbI(4)). The 2D perovskite materials were investigated as light absorbing materials in solid state solar cells. The best performing material under moist, ambient conditions was BdAPbI4 (1.08% efficiency), which was comparable to methylammonium Pb(II) iodide (MAPbI(3)) solar cells (2.1% efficiency) manufactured and studied under analogous conditions. When compared to MAPbI(3), the 2D materials have larger band gaps and lower photoconductivity, while BdAPbI(4) based solar cells shows a comparable absorbed photon-to-current efficiency as compared to MAPbI(3) based ones.

  • 26. Shen, Z.
    et al.
    Xu, Bo
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Liu, Peng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Hu, Y.
    Yu, Y.
    Ding, H.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Hua, J.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi. Dalian University of Technology (DUT), Dalian, China.
    Tian, H.
    High performance solid-state dye-sensitized solar cells based on organic blue-colored dyes2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 3, s. 1242-1247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of novel photosensitizers with very high molar extinction coefficients and broad absorption spectra to enhance the light harvesting efficiency providing high PCEs for solid state dye sensitized solar cells (sDSCs) is a main target for improvement. In this work, two novel organic blue-colored dyes termed S4 and S5 with indeno[1,2-b]thiophene functionalized triphenylamine as the donor, 2,3-diphenylpyrido[3,4-b]pyrazine (PP) or 2,3-diphenylquinoxaline (QT) as the auxiliary acceptor and cyclopentadithiophene (CPDT) as the π-linker were designed and synthesized for sDSCs. S5 containing the QT unit as the electron-withdrawing group exhibits a high molar extinction coefficient of 6.3 × 104 M-1 cm-1 at 600 nm. Most importantly, the S5-based sDSCs shows record PCEs of 7.81% and 8.25% under one sun and 0.5 sun light intensities, respectively, exceeding the PCE of LEG4-based solar cells (7.34%). To the best of our knowledge, this is the first case where an organic blue-colored dye displays a PCE over 7.8% in sDSCs, thus representing record efficiencies for sDSCs. These results clearly show that molecular engineering is a viable way to develop blue-colored dyes with high molar extinction coefficients for use in highly efficient sDSCs. Also, blue-colored dyes open up co-sensitization strategies in combination with traditional organic dyes with yellow-red colours.

  • 27. Strain, I. N.
    et al.
    Wu, Qiong
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Andersson, Richard L.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Electrospinning of recycled PET to generate tough mesomorphic fibre membranes for smoke filtration2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 4, s. 1632-1640Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tough fibrous membranes for smoke filtration have been developed from recycled polyethylene terephthalate (PET) bottles by solution electrospinning. The fibre thicknesses were controlled from 0.4 to 4.3 mu m by adjustment of the spinning conditions. The highest fibre strength and toughness were obtained for fibres with an average diameter of 1.0 mu m, 62.5 MPa and 65.8 MJ m(-3), respectively. The X-ray diffraction (XRD) patterns of the fibres showed a skewed amorphous halo, whereas the differential scanning calorimetry (DSC) results revealed an apparent crystallinity of 6-8% for the 0.4 and 1 mu m fibres and 0.2% crystallinity for the 4.3 mu m fibres. Heat shrinkage experiments were conducted by exposing the fibres to a temperature above their glass transition temperature (T-g). The test revealed a remarkable capability of the thinnest fibres to shrink by 50%, which was in contrast to the 4.3 mu m fibres, which displayed only 4% shrinkage. These thinner fibres aka showed a significantly higher glass transition temperature (+15 degrees C) than that of the 4.3 mu m fibres. The results suggested an internal morphology with a high degree of molecular orientation in the amorphous segments along the thinner fibres, consistent with a constrained mesomorphic phase formed during their rapid solidification in the electric field. Air filtration was demonstrated with cigarette smoke as a model substance passed through the fibre mats. The 0.4 mu m fibres showed the most effective smoke filtration and a capacity to absorb 43x its own weight in smoke residuals. whereas the 1 mu m fibres showed the best combination of filtration capacity (32x) and mechanical robustness. The use of recycled PET in the form of nanofibres is a novel way of turning waste into higher-value products.

  • 28.
    Svanström, Sebastian
    et al.
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Jacobsson, T. Jesper
    Uppsala Univ, Dept Chem, Angstrom Lab, Box 538, S-75121 Uppsala, Sweden..
    Sloboda, Tamara
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Rensmo, Hakan
    Uppsala Univ, Dept Phys & Astron, Div Mol & Condensed Matter Phys, Box 516, SE-75120 Uppsala, Sweden..
    Cappel, Ute B.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Effect of halide ratio and Cs+ addition on the photochemical stability of lead halide perovskites2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 44, s. 22134-22144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lead halide perovskite solar cells with multi-cation/mixed halide materials now give power conversion efficiencies of more than 20%. The stability of these mixed materials has been significantly improved through the addition of Cs+ compared to the original methylammonium lead iodide. However, it remains one of the most significant challenges for commercialisation. In this study, we use photoelectron spectroscopy (PES) in combination with visible laser illumination to study the photo-stability of perovskite films with different compositions. These include Br : I ratios of 50 : 50 and 17 : 83 and compositions with and without Cs+. For the samples without Cs and the 50 : 50 samples, we found that the surface was enriched in Br and depleted in I during illumination and that some of the perovskite decomposed into Pb-0, organic halide salts, and iodine. After illumination, both of these reactions were partially reversible. Furthermore, the surfaces of the films were enriched in organic halide salts indicating that the cations were not degraded into volatile products. With the addition of Cs+ to the samples, photo-induced changes were significantly suppressed for a 50 : 50 bromide to iodide ratio and completely suppressed for perovskites with a 17 : 83 ratio at light intensities exceeding 1 sun equivalent.

  • 29. Tian, Guojian
    et al.
    Cai, Shengyun
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wang, Qiaochun
    Huang, Jinhai
    Su, Jianhua
    A new D-A-pi-A type organic sensitizer based on substituted dihydroindolo [2,3-b] carbazole and DPP unit with a bulky branched alkyl chain for highly efficient DSCs2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 7, s. 3777-3784Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new D-A-pi-A configuration metal-free organic sensitizers (T1-T2) based on 5,7-dihexyl-6,12-diphenyl-5,7-dihydroindolo[2,3-b]carbazole and a DPP unit with a bulky branched alkyl chain have been synthesized for dye-sensitized solar cells. Due to a bulky branched alkyl chain being attached to the donor and DPP unit, both compounds obtain high V-oc values. Under standard global AM 1.5 solar light conditions, the T1 based-device gives a high conversion efficiency of 8.24% with a J(sc) of 15.72 mA cm(-2), a V-oc of 0.74 V and a FF of 0.71. These excellent performances make the donor dihydroindolo[2,3-b] carbazole and DPP unit promising candidates for further application in DSCs.

  • 30.
    Wang, Baoyuan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. Hubei University, China.
    Wang, Yi
    Fan, Liangdong
    Cai, Yixiao
    Xia, Chen
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. Hubei University, China.
    Liu, Yanyan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Raza, Rizwan
    van Aken, Peter A.
    Wang, Hao
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. Hubei University, China.
    Preparation and characterization of Sm and Ca co-doped ceria-La0.6Sr0.4Co0.2Fe0.8O3-delta semiconductor-ionic composites for electrolyte-layer-free fuel cells2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 40, s. 15426-15436Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of Sm and Ca co-doped ceria, i.e. Ca0.04Ce0.96-xSmxO2-delta (x = 0, 0.09, 0.16, and 0.24) (SCDC), were synthesized by a co-precipitation method. Detailed morphology, composition, crystal structure and electrochemical properties of the prepared materials were characterized. The results revealed that Sm and Ca co-doping could enhance the ionic conductivity in comparison with that of single Ca-doped samples. The composition as Ca0.04Ce0.80Sm0.16O2-delta exhibited a highest ionic conductivity of 0.039 S cm(-1) at 600 degrees C in comparison with the rest of the series, and the optimal ionic conductivity can be interpreted by the coupling effect of oxygen vacancies and mismatch between the dopant ionic radius and critical radius. Composite formation between the semiconductor La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) and the as-prepared SCDC contributed to a remarkable improvement in the ionic conductivity, an unexpectedly high ionic conductivity of 0.188 S cm(-1) was obtained for LSCF-SCDC composites at 600 degrees C, which was four times higher than that of pure SCDC. Using transmission electron microscopy and spectroscopy approaches, we detected an enrichment of oxygen in the LSCF-SCDC interface region and a depletion of oxygen vacancies in LSCF-SCDC and LSCF-LSCF grain boundaries was significantly mitigated, which resulted in the enhancement of ionic conductivity of semiconductor-ionic LSCF-SCDC composites. The electrolyte-layer-free fuel cell (EFFC) fabricated from the LSCF-SCDC semiconductor-ionic membrane demonstrated excellent performances, e.g. 814 mW cm(-2) at 550 degrees C for using the LSCF-Ca0.04Ce0.80Sm0.16O2-delta (SCDC2).

  • 31.
    Wang, Haoxin
    et al.
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Yu, Ze
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Lai, Jianbo
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Song, Xinkai
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Yang, Xichuan
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi. DUT, Inst Energy Sci & TechnolROYAL SOC CHEMISTRY, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem,Inst Artificial Photosynt, Dalian 116024, Peoples R China..
    One plus one greater than two: high-performance inverted planar perovskite solar cells based on a composite CuI/CuSCN hole-transporting layer2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 43, s. 21435-21444Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The low-cost and stable inorganic p-type semiconductor copper(i) iodide (CuI) is a promising hole-transporting layer (HTL) material for inverted planar perovskite solar cells (PSCs). However, the power conversion efficiencies (PCEs) of inverted planar PSCs based on CuI HTLs reported so far are not satisfactory and far behind those of their organic counterparts. Herein, we demonstrate a simple but effective approach to improve the performance of inverted planar PSCs based on the CuI HTL through the incorporation of copper thiocyanate (CuSCN) into the CuI HTL. As compared to pristine CuI, the introduction of CuSCN significantly improves the quality of the film, resulting in a smooth and uniform film while maintaining relatively high electrical conductivity. As a consequence, the champion device based on the composite CuI/CuSCN HTL affords an impressive PCE of 18.76% under full sun illumination (100 mW cm(-2), AM 1.5G), which is substantially higher than the corresponding values of the respective devices containing pristine CuI (14.53%) and CuSCN (16.66%). This value is one of the highest efficiencies reported thus far for CuI- and CuSCN-based HTLs in PSCs. This work demonstrates the great potential of low-temperature solution-processed CuI/CuSCN composites as hole-selective layers for low-cost and efficient PSCs as well as other optoelectronic devices.

  • 32. Wang, K.
    et al.
    Körstgens, V.
    Yang, D.
    Hohn, N.
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Biokompositer. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
    Müller-Buschbaum, P.
    Morphology control of low temperature fabricated ZnO nanostructures for transparent active layers in all solid-state dye-sensitized solar cells2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 10, s. 4405-4415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Based on a method using sol-gel chemistry combined with diblock copolymer templating, a low-temperature route to fabricate zinc oxide (ZnO) films with tunable morphologies including foam-like, worm-like and sphere-like structures is demonstrated. The morphologies are probed using scanning electron microscopy and grazing-incidence small-angle X-ray scattering. Based on controlled nanostructured ZnO films, all solid-state dye-sensitized solar cells (ssDSSCs) are prepared, for which every layer is deposited at low temperature to reduce the energy consumption of the manufacturing process. Transparent active layers for ssDSSCs are obtained, which demonstrates the possibility for building integrated solar cells. The ssDSSCs with a worm-like ZnO morphology, exhibiting relatively better ordered interconnected three-dimensional structures and larger meso-pore sizes, show the highest power conversion efficiencies and almost 100% efficiency of charge separation and collection for the absorbed photons. After 120 days, almost 80% of the initial power conversion efficiency is maintained in ambient air conditions, which demonstrates good long-term stability of the ssDSSCs even without special encapsulation. 

  • 33. Wang, Lichao
    et al.
    Wang, Yu
    Cheng, Yao
    Liu, Zhifu
    Guo, Qiangsheng
    Ha, Minh Ngoc
    Zhao, Zhe
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi. School of Materials Science and Engineering, Shanghai Institute of Technology, China.
    Hydrogen-treated mesoporous WO3 as a reducing agent of CO2 to fuels (CH4 and CH3OH) with enhanced photothermal catalytic performance2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 14, s. 5314-5322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of mesoporous WO3 catalysts were facilely synthesized by a hydrothermal method using mesoporous silica KIT-6 as a hard template and silicotungstic acid as a precursor. All the catalysts possess a well-defined mesoporous structure with interconnected networks. Oxygen-deficient mesoporous WO3 (m-WO3-x) was prepared by hydrogenation treatment at different temperatures with improved photothermal coupling performance. Moreover, the as-prepared catalysts exhibit selectivity toward CH4 evolution under visible-light only irradiation. Then, under photothermal conditions, the results show that the concentration of oxygen vacancies of m-WO3 has a great influence on its catalytic performance. The CH4 evolution rate reached 25.77 mu mol g (1), which is about 22 times that of mesoporous WO3 (1.17 mu mol g(-1)) under the same conditions, and a moderate concentration of oxygen vacancies is necessary to achieve selectivity for the conversion of CO2 into CH4. A mechanism of the catalytic reduction of CO2 over m-WO3-x is proposed, in which the initial oxygen vacancies function as an excellent electron transfer mediator and decompose CO2 into its elements (C/CO). These findings may further broaden the scope for photothermal chemical conversion and provide new insights into the oxygen nonstoichiometry strategy for the development of CO2 reduction.

  • 34. Wang, M.
    et al.
    Liu, J.
    Guo, C.
    Gao, X.
    Gong, C.
    Wang, Y.
    Liu, B.
    Li, X.
    Gurzadyan, G. G.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. Dalian University of Technology, China.
    Metal-organic frameworks (ZIF-67) as efficient cocatalysts for photocatalytic reduction of CO2: The role of the morphology effect2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 11, s. 4768-4775Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metal-organic frameworks (MOFs), ZIF-67, with different morphologies were synthesized via a solvent-induced method at room temperature. The photocatalytic performances towards the reduction of CO2 were evaluated by using ZIF-67 materials as cocatalysts cooperating with a ruthenium-based complex as the photosensitizer. It has been demonstrated that the two-dimensional ZIF-67 with a leaf-like morphology exhibited the best photocatalytic activity and stability due to the highest CO2 adsorption capability and efficient electron transfer from the excited [Ru(bpy)3]2+ to ZIF-67.

  • 35.
    Wang, Pengfei
    et al.
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Wang, Jiao
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zhang, Xin
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Wang, Haoliang
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Cui, Xiaolei
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Yuan, Sijian
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Lu, Haizhou
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Tu, Li
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zhan, Yiqiang
    Fudan Univ, Ctr Micronano Syst, State Key Lab ASIC & Syst, SIST, Shanghai 200433, Peoples R China..
    Zheng, Li-rong
    KTH.
    Boosting the performance of perovskite solar cells through a novel active passivation method2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 32, s. 15853-15858Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Potassium halides have recently garnered much attention, due to their improvement of perovskite solar cell performance. A small amount of potassium halide incorporated in a perovskite absorber is able to provide advantages in terms of crystallinity, light absorption and trap state reduction. Here, we present a potassium chloride (KCl) pretreatment process to fabricate high-efficiency perovskite solar cells (PSCs). A KCl layer was inserted at the SnO2/MAPbI(3-x)Cl(x) interface via a simple spin coating method. It is observed that potassium cations (K+) and chloride anions (Cl-) diffused into the perovskite film during the thermal annealing process. The diffusion of K+ and Cl- will stop when they reach a bulk defect, resulting in an active passivation effect. It is verified that the incorporation of KCl enhances the crystal perfection and light absorption of the perovskite film. The average power conversion efficiency (PCE) of PSCs increases from 16.62% to 17.81%, with a leading PCE of 19.44%.

  • 36. Wang, W.
    et al.
    Widmann, T.
    Song, L.
    Fröschl, T.
    Hüsing, N.
    Mo, G.
    Wu, Z.
    Zhang, P.
    Roth, Stephan V.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Fan, H.
    Müller-Buschbaum, P.
    Aging of low-temperature derived highly flexible nanostructured TiO 2 /P3HT hybrid films during bending2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 17, s. 10805-10814Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To meet the demand for low-cost, lightweight, portable and building-integrated solar cells, developing flexible and cost-efficient photo-active hybrid films is of significant interest. In this work, we investigate the mechanical properties of hybrid layers consisting of mesoporous TiO 2 filled with poly(3-hexylthiophene-2,5-diyl) (P3HT) as a function of the number of bending cycles. The TiO 2 /P3HT layers are deposited on flexible PET substrates at low temperatures (≤140 °C), which is beneficial for reducing the processing energy input and in turn lowering the production costs. Non-filled and partially filled mesoporous titania films are studied for comparison. The surface morphology is examined with scanning electron microscopy (SEM) before and after the bending tests. The inner film morphology is characterized with grazing incidence small-angle X-ray scattering (GISAXS). Based on the observed morphology, micromechanical models are used to analyze the mechanical properties of the investigated films. The results show that the TiO 2 /P3HT layers have a low elastic modulus and P3HT helps to stabilize the titania nanostructures against fracture. The SEM observations are well explained with the established models in a quantitative way.

  • 37.
    Watcharatharapong, Teeraphat
    et al.
    Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 530, SE-75121 Uppsala, Sweden. hakraborty, Sudip.
    Chakraborty, Sudip
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala Univ, Dept Phys & Astron, Mat Theory Div, Condensed Matter Theory Grp, Box 530, SE-75121 Uppsala, Sweden.
    Mapping the sodium intercalation mechanism, electrochemical properties and structural evolution in non-stoichiometric alluaudite Na2+2 delta Fe2-delta(SO4)(3) cathode materials2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 29, s. 17446-17455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the scientific advancement of future cathode materials, alluaudite sodium iron sulfate Na2+2 delta Fe2-delta(SO4)(3) (NxFyS) has emerged as one of the most promising candidates for sustainable sodium-ion batteries due to its high Fe2+/3+ redox potential (3.8 V vs. Na/Na+), low cost, and high rate capability. Usually, this material occurs in a non-stoichiometric form with partial Na+ substitutions on Fe sites, where delta is close to 0.25 (N2.5F1.75S) depending on the synthesis conditions. While many contemporary works have primarily been directed to study this non-stoichiometric compound, our previous theoretical prediction unveiled the possibility to synthesize stoichiometric alluaudite (N2F2S), which is expected to deliver higher specific capacity (similar to 120 mA h g(-1)) as compared to the non-stoichiometric derivatives. This provokes curiosity toward the non-stoichiometric effect on the electrochemical activities and sodium intercalation mechanism in alluaudite materials. In this work, we therefore perform rigorous first-principles calculations to study the structural evolution, electrochemical behavior, and voltage profile of NxFyS with y = 2, 1.75, and 1.5. We reveal the likelihood of two phase transitions after half desodiation process, whereas the probability is reduced with a higher degree of non-stoichiometry, suggesting improvement in the structural reversibility for N2.5F1.75S and N3F1.5S. The prediction of the voltage profiles shows the benefit of non-stoichiometry in enhancing the specific capacity and identifies the structural rearrangement of Fe2O10 dimers as the hidden reason behind the irreversible sharp peak experimentally observed in differential galvanostatic profiles.

  • 38. Watcharatharapong, Teeraphat
    et al.
    T-Thienprasert, Jiraroj
    Barpanda, Prabeer
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala University, Sweden.
    Chakraborty, Sudip
    Mechanistic study of Na-ion diffusion and small polaron formation in Krohnkite Na2Fe(SO4)(2)center dot 2H(2)O based cathode materials2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 41, s. 21726-21739Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Krohnkite-type Na2Fe(SO4)(2)center dot 2H(2)O mineral is a sustainable and promising polyanionic cathode that has been experimentally found to offer a high redox potential (3.25 V vs. Na/Na+) along with fast-ion diffusion and high reversibility. Owing to the structural complexity, Na+ diffusion was assumed to occur along a convoluted channel along the b-axis. However, theoretical work related to this material still appears missing to support that statement. In this work, DFT+U calculations have been performed with the primary aim to unveil the Na+ diffusion mechanism in this material. The electronic structure and charge transfer are also envisaged to reveal evidence of Fe2+/3+ redox reaction and a vital role of structural H2O. Based on formation energies of this material with varied Na concentration, a calculated voltage profile is determined to show two voltage plateaus at 4.81 and 3.51 V, corresponding to experimental results. Nudged elastic band calculation reveals that Na+ diffusion is primarily occuring in the [01 (1) over bar] direction with a moderate ionic mobility due to the structural distortion induced during migration, suggesting the possibility of defect-assisted diffusion. Intriguingly, the formation of small hole polarons is first observed, and could play a key role in the electronic conduction of this material.

  • 39.
    Willgert, Markus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Leijonmarck, Simon
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi. Swerea SICOMP AB, Sweden.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Malmström Jonsson, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Johansson, Mats K. G.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Cellulose nanofibril reinforced composite electrolytes for lithium ion battery applications2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 33, s. 13556-13564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study describes the synthesis and characterization of a series of four composite electrolytes for lithium ion battery applications. The two-phase electrolytes are composed of a soft, ionic conductive poly(ethylene glycol) (PEG) matrix having stiff nanofibrillated cellulose (CNF) paper as reinforcement to provide mechanical integrity. The reinforcing CNF is modified in order to create covalent bonds between the phases which is particularly beneficial when swelling the composite with a liquid electrolyte to enhance the ionic conductivity. After swelling the composite polymer electrolyte, forming a gelled structure, values of ionic conductivity at 5 x 10(-5) S cm(-1) and an elastic modulus around 400 MPa at 25 degrees C are obtained.

  • 40.
    Wu, Qiong
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Andersson, Richard L.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Holgate, Tim
    Johansson, Eva
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Highly porous flame-retardant and sustainable biofoams based on wheat gluten and in situ polymerized silica2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 48, s. 20996-21009Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article presents a novel type of flame-retardant biohybrid foam with good insulation properties based on wheat gluten and silica, the latter polymerized in situ from hydrolysed tetraethyl orthosilicate (TEOS). This led to the formation of intimately mixed wheat gluten and silica phases, where, according to protein solubility measurements and infrared spectroscopy, the presence of silica had prohibited full aggregation of the proteins. The foams with "built-in" flame-retardant properties had thermal insulation properties similar to those of common petroleum- and mineral-based insulation materials. The foams, with a porosity of 87 to 91%, were obtained by freeze-drying the liquid mixture. Their internal structure consisted of mainly open cells between 2 and 144 mu m in diameter depending on the foam formulation, as revealed by mercury intrusion porosimetry and scanning electron microscopy. The foams prepared with >= 30% TEOS showed excellent fire-retardant properties and fulfilled the criteria of the best class according to UL94 fire testing standard. With increasing silica content, the foams became more brittle, which was prevented by cross-linking the materials (using gluteraldehyde) in combination with a vacuum treatment to remove the largest air bubbles. X-ray photoelectron and infrared spectroscopy showed that silicon was present mainly as SiO2 .

  • 41. Wu, Zhifang
    et al.
    Li, Xin
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Li, Jing
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Hua, Jianli
    Tian, He
    Effect of bridging group configuration on photophysical and photovoltaic performance in dye-sensitized solar cells2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 27, s. 14325-14333Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three new metal-free organic sensitizers with a D-A-p-A configuration based on a triarylamine donor, 2,1,3-benzothiadiazole (BTD) and different pi units have been synthesized. Because a long alkyl side chain has been attached to the thiophene adjacent to BDT, HECA achieves the best performance. Under standard global AM 1.5 solar light conditions, the HECA based-device gives the best conversion efficiency of 9.13% with a J(sc) of 16.14 mA cm(-2), a V-oc of 0.72 V and a FF of 0.77. Although EDCA displays superior optical properties, it does not give the desired results. The device based on EDCA achieves efficiency of 7.37% with a J(sc) of 15.56 mA cm(-2), a V-oc of 0.67 V and a FF of 0.70. EIS analysis confirms the existence of fast recombination in the EDCA system. Further computational analysis indicates that the coplanarity and the very strong affinity to iodine molecules of EDCA may be the origin of the low performance.

  • 42.
    Wåhlander, Martin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Nilsson, Fritjof
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Andersson, Richard L.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Cobo Sanchez, Carmen
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Taylor, Nathaniel
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Hillborg, Henrik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material. ABB AB.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Tailoring Dielectric Properties using Designed Polymer-Grafted ZnO Nanoparticles in Silicone Rubber2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, s. 14241-14258, artikkel-id C6TA11237DArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polymer grafts were used to tailor the interphases between ZnO nanoparticles (NPs) and silicone matrices. The final electrical properties of the nanocomposites were tuned by the grafted interphases, by controlling the inter-particle distance and the NP-morphology. The nanocomposites can be used in electrical applications where control of the resistivity is desired. Hansen's solubility parameters were used to select a semi-compatible polymer for grafting to obtain anisotropic NP morphologies in silicone, and the grafted NPs self-assembled into various morphologies inside the silicone matrices. The morphologies in the semi-compatible nanocomposites could be tuned by steering the graft length of poly(n-butyl methacrylate) via entropic matrix-graft wetting using surface-initiated atom-transfer radical polymerization. Image analysis models were developed to calculate the radius of primary NPs, the fraction of aggregates, the dispersion, and the face-to-face distance of NPs. The dielectric properties of the nanocomposites were related to the morphology and the face-to-face distance of the NPs. The dielectric losses, above 100 Hz, for nanocomposites with grafted NPs were approximately one decade lower than those of pristine NPs. The isotropic nanocomposites increased the resistivity up to 100 times compared to that of neat silicone rubber, due to the trapping of charge carriers by the interphase of dispersed NPs and nanoclusters. On the other hand, the resistivity of anisotropic nanocomposites decreased 10–100 times when the inter-particle distance in continuous agglomerates was close to the hopping distance of charge carriers. The electrical breakdown strength increased for compatible isotropic nanocomposites, and the temperature dependence of the resistivity and the activation energy were ∼50% lower in the nanocomposites with grafted NPs. These flexible dielectric nanocomposites are promising candidates for low-loss high-voltage transmission cable accessories, mobile electronic devices, wearables and sensors.

  • 43. Ye, Lu
    et al.
    Liu, Jinxuan
    Gao, Yan
    Gong, Chenghuan
    Addicoat, Matthew
    Heine, Thomas
    Woell, Christof
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian University of Technology, China.
    Highly oriented MOF thin film-based electrocatalytic device for the reduction of CO2 to CO exhibiting high faradaic efficiency2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 40, s. 15320-15326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A monolithic, highly electrochemically efficient Re-based metal-organic framework (MOF) thin film has been deposited onto a conductive FTO electrode by liquid-phase epitaxy. The X-ray diffraction (XRD) analysis reveals the presence of a highly oriented film grown exclusively along the [001] direction. This epitaxially-grown SURMOF exhibits an extremely high faradaic efficiency of 93 +/- 5% when operated as an electrocatalyst for the reduction of CO2 to CO. In addition, the obtained current densities of the high-quality monolithic coatings exceed 2 mA cm(-2), a value at least one order of magnitude larger than that reported for previous electrocatalytically active MOF thin films.

  • 44. Zhang, Fuguo
    et al.
    Yang, Xichuan
    Cheng, Ming
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Li, Jiajia
    Wang, Weihan
    Wang, Haoxin
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. Dalian Univ Technol, China.
    Engineering of hole-selective contact for low temperature-processed carbon counter electrodebased perovskite solar cells2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 48, s. 24272-24280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A cost-effective and solution processable hole transport material (HTM), TPDI (5,10,15-triphenyl-5H-diindolo[3,2-a:3',2'-c]carbazole), was synthesized and explored as a hole selective contact material in low temperature (100 degrees C) and printable processed carbon counter electrode based perovskite solar cells (PSCs) for the first time. This material demonstrated excellent thermal stability, high hole mobility and appropriate energy level alignment with CH3NH3PbI3 and carbon, which make it a potentially excellent alternative interfacial material for PSCs. By interfacial engineering with doped TPDI, the energy barrier at the CH3NH3PbI3/carbon interface was efficiently eliminated. Dramatically enhanced power conversion efficiency (PCE) of 15.5% was afforded, which is comparable to or even better than that of the reference device with 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) as HTM under equivalent conditions. Besides, TPDI can also function well in its pristine form although the efficiency (13.6%) obtained is slightly lower than that with the device containing doped TPDI as the HTM. Moreover, these newly integrated noble metal-free, vacuum-free and cost effective PSCs exhibited excellent durability during the long term stability measurements for 30 days. The remarkable performance as well as dramatically reduced fabrication cost demonstrated by integrating TPDI as the HTM and cost effective commercial carbon as the cathode revealed their great potential in the scalable and practical application of PSCs.

  • 45.
    Zhang, Peili
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Chen, Hong
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Wang, Mei
    Yang, Yong
    Jiang, Jian
    Zhang, Biaobiao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Duan, Lele
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Daniel, Quentin
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Li, Fusheng
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology, 116023 Dalian, China .
    Gas-templating of hierarchically structured Ni-Co-P for efficient electrocatalytic hydrogen evolution2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 16, s. 7564-7570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the grand challenges for developing scalable and sustainable hydrogen producing systems is the lack of efficient and robust earth-abundant element based catalysts for the hydrogen evolution reaction (HER). Herein, a hierarchically structured Ni-Co-P film was fabricated via a gas templating electro-deposition method. This film exhibits remarkably high catalytic performance for the HER in 1 M KOH with respective current densities of -10 and -500 mA cm(-2) at the overpotentials of -30 and -185 mV with a Tafel slope of 41 mV dec(-1). A controlled potential electrolysis experiment demonstrates that the as-prepared Ni-Co-P film is an efficient and robust catalyst with a faradaic efficiency close to 100%. Systematic characterization suggests that the unique hierarchical structure and the mutual participation of nano-sized Ni/Co based components are responsible for the high HER catalytic activity.

  • 46.
    Zhao, Xin
    et al.
    Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore..
    Hu, Jun
    Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore.;Northwest Univ, Sch Chem Engn, Xian 710069, Shaanxi, Peoples R China..
    Wu, Bo
    Nanyang Technol Univ, Sch Phys & Math Sci, Singapore 637371, Singapore..
    Banerjee, Amitava
    Uppsala Univ, Mat Theory Div, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Chakraborty, Sudip
    Uppsala Univ, Mat Theory Div, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Feng, Jianyong
    Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore..
    Zhao, Zongyan
    Kunming Univ Sci & Technol, Fac Mat Sci & Engn, Kunming 650093, Yunnan, Peoples R China..
    Chen, Shi
    Nanyang Technol Univ, Sch Phys & Math Sci, Singapore 637371, Singapore..
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Uppsala Univ, Mat Theory Div, Dept Phys & Astron, S-75120 Uppsala, Sweden.
    Sum, Tze Chien
    Nanyang Technol Univ, Sch Phys & Math Sci, Singapore 637371, Singapore..
    Chen, Zhong
    Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore..
    Simultaneous enhancement in charge separation and onset potential for water oxidation in a BiVO4 photoanode by W-Ti codoping2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 35, s. 16965-16974Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Efficient charge separation of photo-generated electrons and holes is critical to achieve high solar to hydrogen conversion efficiency in photoelectrochemical (PEC) water splitting. N-type doping is generally used to improve the conductivity by increasing the majority carrier density and enhance the charge separation in the photoanode. However, minority carrier transport is also very important in the process of charge separation, especially in materials that possess inadequate minority carrier mobility. Herein, we take a BiVO4 PEC water splitting cell as an example to demonstrate how to analyze the limiting factor and to formulate the corresponding solutions to improve the hole mobility. The benefits and problems caused by n-type doping (W-doping here) of BiVO4 are analyzed. Codoping with Ti further enhances the charge separation by improving the hole transport and leads to a cathodic shift of the photocurrent onset potential. A high charge separation efficiency (79% at 1.23 V-RHE) in a compact BiVO4 photoanode has been achieved without any nanostructure formation. Theoretical results show that W-Ti codoping has decreased the hole polaron hopping activation energy by 11.5% compared with mono-W doping, and this has resulted in a hole mobility increase by 29%. The calculated adsorption energy and reaction Gibbs free energies indicate that the Ti site is energetically more favorable for water splitting. Moreover, the Ti site possesses a lower overpotential in the W-Ti codoped sample compared with the mono-W doped sample. The current study indicates that in order to improve the solar energy conversion efficiency, there should be a balanced charge transport of both majority and minority charge carriers. This can be achieved by simply choosing appropriate codoping elements.

  • 47.
    Zhao, Yawei
    et al.
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, Inst Energy Sci & Technol,State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Shen, Junyu
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, Inst Energy Sci & Technol,State Key Lab Fine Chem, Dalian 116024, Peoples R China.;Changshu Inst Technol, Sch Chem & Mat Engn, Jiangsu Lab Adv Funct Mat, Changshu 215500, Jiangsu, Peoples R China..
    Yu, Ze
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, Inst Energy Sci & Technol,State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Hu, Maowei
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, Inst Energy Sci & Technol,State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Liu, Chong
    Jinan Univ, Coll Informat Sci & Technol, Inst New Energy Technol, Guangzhou 510632, Guangdong, Peoples R China..
    Fan, Jiandong
    Jinan Univ, Coll Informat Sci & Technol, Inst New Energy Technol, Guangzhou 510632, Guangdong, Peoples R China..
    Han, Hongxian
    Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, Dalian Natl Lab Clean Energy, Dalian 116023, Peoples R China..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Wang, Mei
    Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, Inst Energy Sci & Technol,State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi. Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, Inst Energy Sci & Technol,State Key Lab Fine Chem, Dalian 116024, Peoples R China.
    Fine-tuning the coordination atoms of copper redox mediators: an effective strategy for boosting the photovoltage of dye-sensitized solar cells2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 20, s. 12808-12814Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Natural systems have marvelously utilized copper complexes featuring sulfur-coordinating ligands, known as blue copper proteins, as efficient electron-transfer mediators in biological processes. Copper complexes with sulfur-coordinating ligands have been attempted as redox mediators in dye-sensitized solar cells (DSCs), the performance of which is not yet satisfactory and still remains less well explored. Herein, we report the application of new copper complexes bearing a tetradentate polythioether ligand, [(S-4)Cu](2+/+) (1(2+/+), S-4 = 1,4,8,11-tetrathiocyclotetradecane), as a redox mediator in DSCs in comparison with its N-4-tetradentate counterpart [(N-4)Cu](2+/+) (2(2+/+), N-4 = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). Impressively, the changes of coordination atoms from N to S positively shift the formal redox potential of the copper complexes by 600 mV, leading to a remarkably high photovoltage approaching 1.0 V. This is one of the highest photovoltage values reported thus far for DSCs based on copper redox mediators.

  • 48.
    Zhao, Yichen
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Sugunan, Abhilash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. SP Tech Res Inst Sweden, Chem Mat & Surfaces Unit, Sweden.
    Schmidt, Torsten
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Fornara, Andrea
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Relaxation is the key to longer life: suppressed degradation of P3HT films on conductive substrates2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 33, s. 13270-13276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here we show the dependence of the degree of degradation of poly-3-hexylthiophene (P3HT) films on the conductivity of the supporting substrate. P3HT is widely used for organic solar cells and electronic devices because it allows simple, low cost fabrication and has potential for the fabrication of flexible devices. However, P3HT is known to have a relatively low photostability, and investigating the photodegradation mechanism is an active research field. We find that P3HT films on conductive substrates show significantly retarded degradation and retain their chemical and morphological features when compared to similar films on glass substrates. This 'substrate effect' in retarding the degradation of P3HT films is evident even upon prolonged exposure to air for up to five months.

  • 49. Zou, Yidong
    et al.
    Wang, Xiangxue
    Ai, Yuejie
    Liu, Yunhai
    Ji, Yongfei
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Wang, Hongqing
    Hayat, Tasawar
    Alsaedi, Ahmed
    Hu, Wenping
    Wang, Xiangke
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    beta-Cyclodextrin modified graphitic carbon nitride for the removal of pollutants from aqueous solution: experimental and theoretical calculation study2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 37, s. 14170-14179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel beta-cyclodextrin modified, multifunctional, layer-by-layer graphitic carbon nitride (g-C3N4/beta-CD) was successfully synthesized and applied as an effective adsorbent for the removal of methyl orange (MO) and Pb(II) from aqueous solutions under various environmental conditions (e.g., solution pH, solid content, contact time and temperature). The kinetic results indicated that the adsorption was dominated by chemisorption, and the higher adsorption capacity of g-C3N4/beta-CD was attributed to it having more oxygen-containing functional groups than g-C3N4. The Langmuir, Freundlich and Sips models were applied to simulate the adsorption isotherms of MO and Pb(II), and the results demonstrated that the adsorption of MO was attributed to multilayer adsorption, while the coverage adsorption of Pb(II) on the g-C3N4/beta-CD was monolayer adsorption. The thermodynamic parameters showed that the adsorption of both MO and Pb(II) was spontaneous and endothermic. The DFT calculations further evidenced the surface complexation and electrostatic interaction of Pb(II) on the g-C3N4 and g-C3N4/beta-CD, whereas, the interaction of MO with g-C3N4 and g-C3N4/beta-CD was mainly attributed to hydrogen bonds and strong pi-pi interactions. The results demonstrated that g-C3N4/beta-CD is a promising material for the efficient removal of organic and inorganic pollutants in environmental pollution remediation.

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