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  • 1.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.;Assiut Univ, Dept Chem, Adv Multifunct Mat Lab, Assiut 71515, Egypt..
    El-Zohry, Ahmed M.
    Uppsala Univ, Dept Chem, Angstrom Labs, POB 523, S-75120 Uppsala, Sweden..
    Cong, Jiayan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Thersleff, Thomas
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Karlsson, Karl Martin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Zou, Xiaodong
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Towards implementing hierarchical porous zeolitic imidazolate frameworks in dye-sensitized solar cells2019In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 6, no 7, article id 190723Article in journal (Refereed)
    Abstract [en]

    A one-pot method for encapsulation of dye, which can be applied for dye-sensitized solar cells (DSSCs), and synthesis of hierarchical porous zeolitic imidazolate frameworks (ZIF-8), is reported. The size of the encapsulated dye tunes the mesoporosity and surface area of ZIF-8. The mesopore size, Langmuir surface area and pore volume are 15 nm, 960-1500 m(2). g(-1) and 0.36-0.61 cm(3). g(-1), respectively. After encapsulation into ZIF-8, the dyes show longer emission lifetimes (greater than 4-8-fold) as compared to the corresponding non-encapsulated dyes, due to suppression of aggregation, and torsional motions.

  • 2. Baranov, A. I.
    et al.
    Isaeva, A. A.
    Kloo, Lars A.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Kulbachinskii, V. A.
    Lunin, R. A.
    Nikiforov, V. N.
    Popovkin, B. A.
    2D metal slabs in new nickel-tin chalcogenides Ni(7-delta)SnQ(2) (Q=Se, Te): average crystal and electronic structures, chemical bonding and physical properties2004In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 177, no 10, p. 3616-3625Article in journal (Refereed)
    Abstract [en]

    A systematic search for mixed low-valence, nickel-tin chalcogenides performed by establishing phase relations in the parts of Ni-Sn-Se and Ni-Sn-Te ternary systems resulted in the discovery of two new compounds, Ni5.62SnSe2 and Ni5.78SnTe2 Single crystals of both compounds were prepared by chemical transport with iodine and crystal structures were determined by single crystal X-ray investigation. The ED patterns for Ni5.78SnTe2 showed the presence of satellite reflections, which indicate a modulated structure with qapproximate to0.4a*. Average crystal structures of both compounds were determined to be of tetragonal symmetry (Sp.gr.I4/mmm, Z = 2) with a = 3.6890(8) Angstrom, c = 18.648(3) Angstrom, R-w = 0.0716 and a = 3.7680(5) Angstrom, c = 19.419(4) Angstrom, R-w, 0.0832, correspondingly, and are isostructural to known Ni5.72SbSe2 and Ni5.66SbTe2. Measurements were carried out for both compounds with respect to thermal, electrical and magnetic properties. Ab initio band structure calculations were also performed to take a first glance into the electronic structure of such type compounds. The anisotropy of their band structure was found. Physical property measurements showed both compounds to be the anisotropic metallic conductors and paramagnetics. Calculated difference charge density maps revealed pairwise covalent and multicenter metallic nature of the d-metal-chalcogen and d-metal-p-metal interactions, respectively.

  • 3. Baranov, A. I.
    et al.
    Isaeva, A. A.
    Kloo, Lars A.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Popovkin, B. A.
    New metal-rich sulfides Ni6SnS2 and Ni9Sn2S2 with a 2D metal framework: Synthesis, crystal structure, and bonding2003In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, no 21, p. 6667-6672Article in journal (Refereed)
    Abstract [en]

    Two new, metal-rich nickel-tin sulfides Ni6SnS2 and Ni9Sn2S2 were found by establishing phase relations in the ternary Ni-Sn-S system at 540 degreesC. Their single crystals were prepared by means of chemical vapor transport reactions. Single crystal X-ray diffraction was used for the determination of their crystal structures. Both compounds crystallize in a tetragonal system (/4/mmm, No. 139, Z = 2, a = 3.646(1) Angstrom, c = 18.151(8) Angstrom for Ni6SnS2, and a = 3.678(1) Angstrom, c = 25.527(8) Angstrom for Ni9Sn2S2). Their crystal structures represent a new structure type and can be considered as assembled from bimetallic nickel-tin and nickel-sulfide slabs alternating along the crystallographic c axis. DFT band structure calculations showed the bonding within the bimetallic slabs to have a delocalized, multicenter nature, typical for metallic systems, and predominantly classical, pairwise bonding between nickel and sulfur.

  • 4. Baranov, A. I.
    et al.
    Kloo, Lars A.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Olenev, A. V.
    Popovkin, B. A.
    Romanenko, A. I.
    Quasi-1D cations (1)(infinity) Ni8Bi8S (n+) of variable charge: Infinite columns (1)(infinity) Ni8Bi8S (2+) in the novel compound Ni(8)Bi(8)Sl(2)2003In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, no 13, p. 3988-3993Article in journal (Refereed)
    Abstract [en]

    The new compound Ni(8)Bi(8)Sl(2) has been synthesized and its crystal structure determined by X-ray crystallography. The structure contains one-dimensional (1D) cations (1)(infinity)[Ni8Bi8S](2+) separated by iodine anions. The geometry of the columns is similar to that of the recently reported (1)(infinity)[Ni8Bi8S](+), and the main difference between them is only their formal charge. Electronic structure calculations and physical properties measurements were performed to analyze the influence of the number of valence electrons on the bonding and properties of compounds containing these 1D cations. It was shown that the removal of one electron (i.e., (1)(infinity)[Ni8Bi8S](+) --> (1)(infinity)[Ni8Bi8S](2+)) mainly affects the Ni-S bonding within the cation and essentially has no influence on the intermetallic Ni-Bi bonding. It was found that Ni(8)Bi(8)Sl(2) containing double-charged columns has conductivity properties more similar to a pure 1D metal than the congener Ni(8)Bi(8)Sl containing mono-charged columns.

  • 5. Baranov, A. I.
    et al.
    Kloo, Lars A.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Olenev, A. V.
    Popovkin, B. A.
    Romanenko, A. I.
    Shevelkov, A. V.
    Unique (infinity Ni8Bi8S)-Ni-1 metallic wires in a novel quasi-1D compound. Synthesis, crystal and electronic structure, and properties of Ni8Bi8SI2001In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 123, no 49, p. 12375-12379Article in journal (Refereed)
    Abstract [en]

    A new quasi-one-dimensional compound Ni8Bi8SI has been synthesized and its crystal structure determined from single-crystal X-ray diffraction data. The structure of Ni8Bi8SI consists of [(infinityNi8Bi8S)-Ni-1] columns separated by iodine atoms. Conductivity and magnetic susceptibility measurements (down to 4.2 K) show that Ni8Bi8SI is a one-dimensional metal and exhibits Pauli paramagnetic properties. These observations are in good agreement with the results from electronic structure calculations. An analysis of the chemical bonding employing difference electron charge density maps reveals strong multicenter Ni-Bi bonds and pair Ni-S interactions within the [(infinityNi8Bi8S)-Ni-1] columns. Only electrostatic interactions are inferred between the columns and iodine atoms.

  • 6. Bergstrom, P. O.
    et al.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Sebhatu, T.
    Crystal structure and physical properties of two polymorphs of ropivacaine HCl2006In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 95, no 3, p. 680-688Article in journal (Refereed)
    Abstract [en]

    The crystal structure of two polymorphs of ropivacaine HCl have been determined, as well as their relative stability up to 100 degrees C. A geometric restriction for a solid-state transition between the two polymorphs has been identified. The packing density along the H-bonded chains form the basis for a model explaining the kinetic crystallization of the metastable form. The difference in stability and physicochemical properties between the two polymorphs can be attributed to the difference in crystal structure.

  • 7.
    Bhagavathiachari, Muthuraaman
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Elumalai, V.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Polymer-doped molten salt mixtures as a new concept for electrolyte systems in dye-sensitized solar cells2017In: ACS Omega, E-ISSN 2470-1343, Vol. 2, no 10, p. 6570-6575Article in journal (Refereed)
    Abstract [en]

    A conceptually new polymer electrolyte for dye-sensitized solar cells is reported and investigated. The benefits of using this type of electrolyte based on ionic liquid mixtures (ILMs) and room temperature ionic liquids are highlighted. Impedance spectroscopy and transient electron measurements have been used to elucidate the background of the photovoltaic performance. Even though larger recombination losses were noted, the high ion mobility and conductivity induced in the ILMs by the added polymer result in enhanced overall conversion efficiencies.

  • 8.
    Bhagavathiachari, Muthuraaman
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Elumalai, Viswanathan
    Vlachopoulos, Nick
    Safdari, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Gardner, James M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    A quasi-liquid polymer-based cobalt redox mediator electrolyte for dye-sensitized solar cells2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 40, p. 17419-17425Article in journal (Refereed)
    Abstract [en]

    Recently, cobalt redox electrolyte mediators have emerged as a promising alternative to the commonly used iodide/triiodide redox shuttle in dye-sensitized solar cells (DSCs). Here, we report the successful use of a new quasi-liquid, polymer-based electrolyte containing the Co3+/Co2+ redox mediator in 3-methoxy propionitrile solvent in order to overcome the limitations of high cell resistance, low diffusion coefficient and rapid recombination losses. The performance of the solar cells containing the polymer based electrolytes increased by a factor of 1.2 with respect to an analogous electrolyte without the polymer. The performances of the fabricated DSCs have been investigated in detail by photovoltaic, transient electron measurements, EIS, Raman and UV-vis spectroscopy. This approach offers an effective way to make high-performance and long-lasting DSCs.

  • 9. Briggner, Lars-Erik
    et al.
    Hendrickx, Ramon
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Rosdahl, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Solid-State Perturbation for Solubility Improvement: A Proof of Concept2011In: ChemMedChem, ISSN 1860-7179, Vol. 6, no 1, p. 60-62Article in journal (Refereed)
    Abstract [en]

    Simple and rational: The intrinsic solubility of a compound can be systematically improved by perturbing key interactions in its crystal structure. By carefully choosing the perturbation, the end result will be a molecule similar to the original one, but with significantly higher solubility. This methodology is demonstrated on a subset of benzodiazepines, resulting in significant improvement of their solubility.

  • 10. Briggner, Lars-Erik
    et al.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Rosdahl, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    In Silico Solid State Perturbation for Solubility Improvement2014In: ChemMedChem, ISSN 1860-7179, E-ISSN 1860-7187, Vol. 9, no 4, p. 724-726Article in journal (Refereed)
    Abstract [en]

    Solubility is a frequently recurring issue within pharmaceutical industry, and new methods to proactively resolve this are of fundamental importance. Here, a novel methodology is reported for intrinsic solubility improvement, using insilico prediction of crystal structures, by perturbing key interactions in the crystalline solid state. The methodology was evaluated with a set of benzodiazepine molecules, using the two-dimensional molecular structure as the only a priori input. The overall trend in intrinsic solubility was correctly predicted for the entire set of benzodiazepines molecules. The results also indicate that, in drug compound series where the melting point is relatively high (i.e., brick dust compounds), the reported methodology should be very suitable for identifying strategically important molecular substitutions to improve solubility. As such, this approach could be a useful predictive tool for rational compound design in the early stages of drug development.

  • 11.
    Bring, Torun
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Jonson, Bo
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Potassium sulfate droplets and the origin of turbidity in alabaster glasses2006In: Glass Technology, ISSN 0017-1050, Vol. 47, no 1, p. 15-18Article in journal (Refereed)
    Abstract [en]

    A study of the criteria required to manufacture multicomponent semi-transparent silicate glasses, so called 'alabaster' glasses, has found that the optical effect is caused by noncrystalline potassium sulfate droplets. The droplets were characterised by use of XRD, SEM/EDX and Raman spectroscopy. The size range of the particles is of the order of 5-50 micrometers. It was found that the droplets consisted of potassium sulfate, even if other sulfate compounds were added to the glass. The amount of sulfate compound added, the melting temperature of the furnace and the melting time have significant effects on the optical density of the glass. The optical density of the glass can be correlated to the calculated surface tension of the host glass, suggesting that phase separation of a sulfate enriched liquid phase is part of the mechanism forming the droplets. By adding pigments several different colours can be obtained, but the alabaster effect is not achieved during reducing conditions, thus it seems not possible to produce colours originating from reduced pigments. Pigments tested were Cr, Fe, Co, Cu, Au, Mo/Se, Nd and Ti/Ce/Se.

  • 12.
    Bring, Torun
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Jonson, Bo
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Rosdahl, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Colour development in copper ruby alkali silicate glasses.: Part 2. The effect of tin (II) oxide and antimony (III) oxide2007In: GLASS TECHNOLOGY-EUROPEAN JOURNAL OF GLASS SCIENCE AND TECHNOLOGY PART A, ISSN 1753-3546, Vol. 48, no 3, p. 142-148Article in journal (Refereed)
    Abstract [en]

    The effect of Sb3+ and Sn2+ during the heat treatment of copper ruby alkali silicate glasses is investigated. The reducing power of SnO and Sb2O3 with respect to Cu is investigated and it is concluded that SnO has the strongest reducing capability. When Cu2O and SnO concentrations are low, minor additions of Sb2O3 have an observable impact on colour development and absorbance, as thin pieces of glass develop a bluish tint and a larger shift towards longer wavelengths is observed in UV/vis spectra. The differences in colour and spectra are suggested to be caused by differences in size of the colour forming agent, Cu metal particles.

  • 13.
    Bring, Torun
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Jonson, Bo
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Carlson, Stefan
    Selenium: molybdenum-based coloration of alkali silicate glasses2007In: Glass Technology, ISSN 0017-1050, Glass Technology - European Journal of Glass Science and Technology Part A, Vol. 48, no 5, p. 213-221Article in journal (Refereed)
    Abstract [en]

    The interaction between selenium and molybdenum in reduced alkali silicate melts, resulting in red glasses has been studied. The oxidation state of Mo is Mo(VI) as evidenced by XANES and ESCA results. Selenium is present in a reduced state, as indicated by ultraviolet/visible spectroscopy and XANES. The colour is described by ultraviolet/visible spectra and CIE colour coordinates. The main absorption peaks are at 450 and 540 nm. Similar bands are reported for MoOSe32−. Several commonly used glass components must be avoided in the batch, as they prevent formation of the red colour.

  • 14. Bring, Torun
    et al.
    Jonson, Bo
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Carlson, Stefan
    Selenium-molybdenum-based colouration of alkali silicate glasses2007In: Glass Technology: European Journal of Glass Science and Technology Part A, ISSN 1753-3546, Vol. 48, no 5, p. 213-221Article in journal (Refereed)
    Abstract [en]

    The interaction between selenium and molybdenum in reduced alkali silicate melts, resulting in red glasses has been studied. The oxidation state of Mo is Mo(VI) as evidenced by XANES and ESCA results. Selenium is present in a reduced state, as indicated by ultraviolet/visible spectroscopy and XANES. The colour is described by ultraviolet/visible spectra and CIE colour coordinates. The main absorption peaks are at 450 and 540 nm. Similar bands are reported for MoOSe32-. Several commonly used glass components must be avoided in the batch, as they prevent formation of the red colour.

  • 15.
    Bring, Torun
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Jonson, Bo
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Rosdahl, Jan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wallenberg, Reine
    Colour development in copper ruby alkali silicate glasses.: Part 1. The impact of tin(II) oxide, time and temperature2007In: GLASS TECHNOLOGY-EUROPEAN JOURNAL OF GLASS SCIENCE AND TECHNOLOGY PART A, ISSN 1753-3546, Vol. 48, no 2, p. 101-108Article in journal (Refereed)
    Abstract [en]

    The development of the red colour in copper ruby alkali silicate glasses has been studied by means of ultraviolet/visible spectroscopy, TEM and EXAFS. The results show that in both red and slightly overstruck, brownish glasses the colour is due to clusters of metallic copper. Before striking non-coloured glasses contain mainly cuprous ions, Cu+. Tin acts as a reducing agent but also has an accelerating effect on colour development.

  • 16.
    Cappel, Ute B.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Liu, Peng
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Johansson, Fredrik O. L.
    Uppsala Univ, Div Mol & Condensed Matter Phys, Dept Phys & Astron, SE-75120 Uppsala, Sweden..
    Philippe, Bertrand
    Uppsala Univ, Div Mol & Condensed Matter Phys, Dept Phys & Astron, SE-75120 Uppsala, Sweden..
    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..
    Lindblad, Andreas
    Uppsala Univ, Div Mol & Condensed Matter Phys, Dept Phys & Astron, SE-75120 Uppsala, Sweden..
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Gardner, James M.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Rensmo, Hakan
    Uppsala Univ, Div Mol & Condensed Matter Phys, Dept Phys & Astron, SE-75120 Uppsala, Sweden..
    Electronic Structure Characterization of Cross-Linked Sulfur Polymers2018In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 19, no 9, p. 1041-1047Article in journal (Refereed)
    Abstract [en]

    Cross-linked polymers of elemental sulfur are of potential interest for electronic applications as they enable facile thin-film processing of an abundant and inexpensive starting material. Here, we characterize the electronic structure of a cross-linked sulfur/diisopropenyl benzene (DIB) polymer by a combination of soft and hard X-ray photoelectron spectroscopy (SOXPES and HAXPES). Two different approaches for enhancing the conductivity of the polymer are compared: the addition of selenium in the polymer synthesis and the addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) during film preparation. For the former, we observe the incorporation of Se into the polymer structure resulting in a changed valence-band structure. For the latter, a Fermi level shift in agreement with p-type doping of the polymer is observed and also the formation of a surface layer consisting mostly of TFSI anions.

  • 17. Cerenius, Y.
    et al.
    Oskarsson, A.
    Santesson, S.
    Nilsson, S.
    Kloo, Lars A.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Preliminary tests on the use of an acoustic levitator for liquid X-ray diffraction experiments2003In: Journal of applied crystallography, ISSN 0021-8898, E-ISSN 1600-5767, Vol. 36, p. 163-164Article in journal (Refereed)
    Abstract [en]

    Some preliminary tests at the crystallography beamline I711 at the MAX II synchrotron in Lund, Sweden, have shown that it is possible to use acoustical levitation to keep a droplet of liquid and solid (powder) samples in an X-ray beam for a sufficient time for collection of the X-ray diffraction pattern.

  • 18. Chen, C.
    et al.
    Cheng, M.
    Li, H.
    Qiao, F.
    Liu, Peng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Kloo, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Molecular engineering of ionic type perylenediimide dimer-based electron transport materials for efficient planar perovskite solar cells2018In: Materials Today Energy, ISSN 2468-6069, Vol. 9, p. 264-270Article in journal (Refereed)
    Abstract [en]

    The main of this work is to overcome the drawbacks of the traditional fullerene derivatives used as electron transport materials (ETMs) for perovskite solar cells (PSCs). Herein, a new strategy to design non-fullerene ETMs is presented by molecular engineering to include charged moieties in the ETM. The designed ETM FA2+-PDI2 is intrinsically ionic and the incorporated counter ions in FA2+-PDI2 significantly increase the electron conductivity and improve the film formation properties. Through careful device optimization, PSCs based on the ionic ETM FA2+-PDI2 exhibit an impressive average power conversion efficiency (PCE) of 17.0%, which is comparable to the PSC based on PC61BM (17.5%). The superior photovoltaic performance can be attributed to efficient electron extraction and effective electron transfer in the PSCs. This work provides important insights regarding the future design of new and efficient non-fullerene ETMs for PSCs. 

  • 19.
    Chen, Cheng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Cheng, Ming
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Application of benzodithiophene based A-D-A structured materials in efficient perovskite solar cells and organic solar cells2016In: Nano Energy, ISSN 2211-2855, Vol. 23, p. 40-49Article in journal (Refereed)
    Abstract [en]

    In this work, we have designed and synthesized a novel molecular material, BDT-C1, in which the core unit, benzodithiophene (BDT), was functionalized by thiophene (TP) and benzo-[c][1,2,5]-thiadiazole (BTZ) derivatives to generate extended pi-conjugation. BDT-C1 shows high hole mobility and high conductivity in its pristine form, in combination with appropriate energy level alignment with respect to [CH3NH3]PbI3 and PC70BM, qualifying the material as a good candidate for application both in perovskite solar cells (PSCs) as dopant-free hole transport material (HTM) and in OSCs as donor material. The champion PSCs based on BDT-C1 show an average conversion efficiency (PCE) of 13.4% (scan forward: 13.9%; scan backward: PCE=12.9%, scan rate: 10 mV/s). Although the average efficiency obtained is slightly lower than that of reference devices based on the well-known doped HTM Spiro-OMeTAD (13.7%), the BDT-C1 based devices exhibit better stability. Moreover, BDT-C1 as a donor material in OSCs also shows good performance in combination with PC70BM as acceptor material, and an efficiency of 6.1% was obtained. The present results demonstrate that BDT-C1 works well as both donor material in OSCs as well as dopant-free HTMs for efficient PSCs.

  • 20. Chen, Cheng
    et al.
    Zhang, Wei
    Cong, Jiayan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Cheng, Ming
    Zhang, Biaobiao
    Chen, Hong
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Li, Ruifeng
    Safdari, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    Cu(II) Complexes as p-Type Dopants in Efficient Perovskite Solar Cells2017In: ACS Energy Letters, E-ISSN 2380-8195, Vol. 2, no 2, p. 497-503Article in journal (Refereed)
    Abstract [en]

    In this work, two Cu(II) complex compounds are designed and synthesized for applications as p-type dopants in solid-state perovskite solar cells (PSCs). Through the characterization of the optical and electrochemical properties, the complex Cu(bpcm)(2) is shown to be eligible for oxidization of the commonly used hole-transport material (HTM) SpiroOMeTAD. The reason is the electron-withdrawing effect of the chloride groups on the ligands. When the complex was applied as p-type dopant in PSCs containing Spiro-OMeTAD as HTM, an efficiency as high as 18.5% was achieved. This is the first time a Cu(II) pyridine complex has been used as p-type dopant in PSCs.

  • 21. Chen, Song
    et al.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hua, Yong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Yuanyuan
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Wang, Xingzhu
    Ong, Beng
    Wong, Wai-Kwok
    Zhu, Xunjin
    Study of Arylamine-Substituted Porphyrins as Hole-Transporting Materials in High-Performance Perovskite Solar Cells2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 15, p. 13231-13239Article in journal (Refereed)
    Abstract [en]

    To develop new hole-transporting materials (HTMs) for efficient and stable perovskite solar. cells (PSCs), 5,10,15,20-tetrakis{4-[N,N-di(4-thethoxylphenyl)amino-phenyl]}-porphyrin was prepared in gram scale through the direct condensation of pyrrole and 4-[bis(4-methoxyphenyl)amino]-benzaldehyde. Its Zn(II) and Cu(II) complexes exhibit excellent thermal and electrochemical stability, specifically a high hole Mobility and very favorable energetics for hole extraction that render them a new class of HTMs in organometallic halide PSCs. As expected, ZnP as HTM in PSCs affords a competitive power conversion efficiency (PCE) of 17.78%,which is comparable to that of the most powerful HTM of Spiro-MeOTAD (18.59%) under the same working conditions. Mean-While, the metal centers affect somewhat the photovoltaic performances that CuP as HTM produces a lower PCE of 15.36%. Notably, the PSCs employing ZnP show a much,better stability than Spiro-OMeTAD. Moreover, the two-porphyrin-based HTMs can be prepared from relatively cheap raw materials with a facile synthetic route. The results demonstrate that ZnP and CuP can be a new class of HTMs for efficient and stable PSCs. To the best of our knowledge, this is the best performance that porphyrin-based solar cells could show with PCE > 17%.

  • 22.
    Cheng, Ming
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Aitola, Kerttu
    Chen, Cheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zhang, Fuguo
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sveinbjornsson, Kari
    Hua, Yong
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Boschloo, Gerrit
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian Univ Technol.
    Acceptor Donor Acceptor type ionic molecule materials for efficient perovskite solar cells and organic solar cells2016In: NANO ENERGY, ISSN 2211-2855, Vol. 30, p. 387-397Article in journal (Refereed)
    Abstract [en]

    Perovskite solar cells (PSCs) have attracted significant interest and hole transporting materials (HTMs) play important roles in achieving high efficiency. Here, we report additive free ionic type HTMs that are based on 2-ethylhexyloxy substituted benzodithiophene (BDT) core unit. With the ionization of end-capping pyridine units, the hole mobility and conductivity of molecular materials are greatly improved. Applied in PSCs, ionic molecular material M7-TFSI exhibits the highest efficiency of 17.4% in the absence of additives [lithium bis(trifluor-omethanesulfonyl)imide and 4-tert-butylpyridine]. The high efficiency is attributed to a deep highest occupied molecular orbital (HOMO) energy level, high hole mobility and high conductivity of M7-TFSI. Moreover, due to the higher hydrophobicity of M7-TFSI, the corresponding PSCs showed better stability than that of Spiro-OMeTAD based ones. In addition, the strong absorption and suitable energy levels of materials (M6, M7-13r and M7-TFSI) also qualify them as donor materials in organic solar cells (OSCs) and the devices containing M7-TFSI as donor material displayed an efficiency of 6.9%.

  • 23.
    Cheng, Ming
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chen, Cheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Aitola, Kerttu
    Zhang, Fuguo
    Hua, Yong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Boschloo, Gerrit
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    Highly Efficient Integrated Perovskite Solar Cells Containing a Small Molecule-PC70BM Bulk Heterojunction Layer with an Extended Photovoltaic Response Up to 900 nm2016In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 28, no 23, p. 8631-8639Article in journal (Refereed)
    Abstract [en]

    We demonstrate a high efficiency perovskite solar cell (PSC) integrated with a bulk heterojunction layer, based on acceptor-donor-acceptor (A-D-A) type hole transport material (HTM) and PC70BM composite, yielding improved photoresponse. Two A-D-A-structured hole transporting materials termed M3 and M4 were designed and synthesized. Applied as HTMs in PSCs, power conversion efficiencies (PCEs) of 14.8% and 12.3% were obtained with M3 and M4, respectively. The HTMs M3 and M4 show competitive absorption, but do not contribute to photocurrent, resulting in low current density. This issue was solved by mixing the HTMs with PC70BM to form a bulk heterojunction (BHJ) layer and integrating this layer into the PSC as hole transport layer (HTL). Through careful interface optimization, the (FAPbI(3))(0.85)(MAPbBr(3))(0.15)/HTM:PC70BM integrated devices showed improved efficiencies of 16.2% and 15.0%, respectively. More importantly, the incident-photon-to-current conversion efficiency (IPCE) spectrum shows that the photoresponse is extended to 900 nm by integrating the M4:PC70BM based BHJ and (FAPbI(3))(0.85)(MAPbBr(3))(0.15) layers.

  • 24.
    Cheng, Ming
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chen, Cheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hua, Yong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Fuguo
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    A novel phenoxazine-based hole transport material for efficient perovskite solar cell2015In: Journal of Energy Challenges and Mechanics, E-ISSN 2056-9386, Vol. 24, no 6, p. 698-706Article in journal (Refereed)
    Abstract [en]

    Based on the previous research work in our laboratory, we have designed and synthesized a small-molecule, hole transport material (HTM) POZ6-2 using phenoxazine (POZ) as central unit and dicyanovinyl units as electron-withdrawing terminal groups. Through the introduction of a 2-ethyl-hexyl bulky chain into the POZ core unit, POZ6-2 exhibits good solubility in organic solvents. In addition, POZ6-2 possesses appropriate energy levels in combination with a high hole mobility and conductivity in its pristine form. Therefore, it can readily be used as a dopant-free HTM in perovskite solar cells (PSCs) and a conversion efficiency of 10.3% was obtained. The conductivity of the POZ6-2 layer can be markedly enhanced via doping in combination with typical additives, such as 4-tert-butylpyridine (TBP) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). Correspondingly, the efficiency of the PSCs was further improved to 12.3% using doping strategies. Under the same conditions, reference devices based on the well-known HTM Spiro-OMeTAD show an efficiency of 12.8%.

  • 25.
    Cheng, Ming
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Yuanyuan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zhang, Fuguo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hajian, Alireza
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Wang, Haoxin
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT–KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), Dalian, China.
    Li, Jiajia
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT–KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), Dalian, China.
    Wang, Linqin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Yang, Xichuan
    State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT–KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), Dalian, China.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT–KTH Joint Education and Research Centre on Molecular Devices, Dalian University of Technology (DUT), Dalian, China.
    A Perylenediimide Tetramer-Based 3D Electron Transport Material for Efficient Planar Perovskite Solar Cell2017In: Solar RRL, E-ISSN 2367-198X, Vol. 1, no 5, article id 1700046Article in journal (Refereed)
    Abstract [en]

    A perylenediimide (PDI) tetramer-based three dimensional (3D) molecular material, termed SFX-PDI4, has been designed, synthesized, and characterized. The low-lying HOMO and LUMO energy levels, high electron mobility and good film-formation property make it a promising electron transport material (ETM) in inverted planar perovskite solar cells (PSCs). The device exhibits a high power conversion efficiency (PCE) of 15.3% with negligible hysteresis, which can rival that of device based on PC61BM. These results demonstrate that three dimensional PDI-based molecular materials could serve as high performance ETMs in PSCs.

  • 26.
    Cheng, Ming
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Li, Yuanyuan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Safdari, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Chen, Cheng
    Liu, Peng
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Efficient Perovskite Solar Cells Based on a Solution Processable Nickel(II) Phthalocyanine and Vanadium Oxide Integrated Hole Transport Layer2017In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 7, no 14, article id 1602556Article in journal (Refereed)
    Abstract [en]

    An organic-inorganic integrated hole transport layer (HTL) composed of the solution-processable nickel phthalocyanine (NiPc) abbreviated NiPc-(OBu)(8) and vanadium(V) oxide (V2O5) is successfully incorporated into structured mesoporous perovskite solar cells (PSCs). The optimized PSCs show the highest stabilized power conversion efficiency of up to 16.8% and good stability under dark ambient conditions. These results highlight the potential application of organic-inorganic integrated HTLs in PSCs.

  • 27.
    Cheng, Ming
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Chen, C.
    Yang, X.
    Zhang, F.
    Tan, Q.
    Hua, Yong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Phenoxazine-based small molecule material for efficient perovskite solar cells and bulk heterojunction organic solar cells2015In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 5, no 8, article id 1401720Article in journal (Refereed)
    Abstract [en]

    The phenoxazine-based acceptor-donor-acceptor structured small-molecule material M1 is used either as a hole-transport material in (CH<inf>3</inf>NH<inf>3</inf>)PbI<inf>3</inf>-perovskite-based solar cells or as photoactive donor material in bulk heterojunction organic solar cells. Excellent power conversion efficiencies of 13.2% and 6.9% are achieved in these two types of photovoltaic devices, respectively.

  • 28.
    Cong, Jiayan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hao, Yan
    Boschloo, Gerrit
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Electrolytes Based on TEMPO-Co Tandem Redox Systems Outperform Single Redox Systems in Dye-sensitized Solar Cells2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 2, p. 264-268Article in journal (Refereed)
    Abstract [en]

    A new TEMPO-Co tandem redox system with TEMPO and Co(bpy)(3)(2+/3+) has been investigated for the use in dye-sensitized solar cells (DSSCs). A large open-circuit voltage (V-OC) increase, from 862 mV to 965 mV, was observed in the tandem redox system, while the short-circuit current density (J(SC)) was maintained. The conversion efficiency was observed to increase from 7.1% for cells containing the single Co(bpy)(3)(2+/3+) redox couple, to 8.4% for cells containing the TEMPO-Co tandem redox system. The reason for the increase in V-OC and overall efficiency is ascribed to the involvement of partial regeneration of the sensitizing dye molecules by TEMPO. This assumption can be verified through the observed much faster regeneration dynamics exhibited in the presence of the tandem system. Using the tandem redox system, the faster recombination problem of the single TEMPO redox couple is resolved and the mass-transport of the metal-complex-based electrolyte is also improved. This TEMPO-Co tandem system is so far the most effienct tandem redox electrolyte reported not involving iodine. The current results show a promising future for tandem system as replacements for single redox systems in electrolytes for DSSCs.

  • 29.
    Cong, Jiayan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hao, Yan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Two Redox Couples are Better Than One: Improved Current and Fill Factor from Cobalt-Based Electrolytes in Dye-Sensitized Solar Cells2014In: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 4, no 8, p. 1301273-Article in journal (Refereed)
    Abstract [en]

    A tandem redox strategy is used in cobalt-based electrolytes. Co(bpy) 3 2+/Co(bpy)3 3+ offers a high photovoltage at the photoanode, whereas the I-/I3 - or Fc/Fc+ redox couples facilitate charge transfer at the counter electrode. Electron exchange in the electrolyte offers beneficial concentration gradients. The overall conversion efficiency is improved from 6.5% to 7.5%.

  • 30.
    Cong, Jiayan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kinschel, Dominik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Dyenamo AB, Sweden.
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Safdari, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gabrielsson, E.
    Chen, Hong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. SP Process Development Forskargatan, Sweden.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bis(1,1-bis(2-pyridyl)ethane)copper(i/II) as an efficient redox couple for liquid dye-sensitized solar cells2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 38, p. 14550-14554Article in journal (Refereed)
    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.

  • 31. Cong, Jiayan
    et al.
    Yang, Xichuan
    Hao, Yan
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A highly efficient colourless sulfur/iodide-based hybrid electrolyte for dye-sensitized solar cells2012In: RSC Advances, ISSN 2046-2069, Vol. 2, no 9, p. 3625-3629Article in journal (Refereed)
    Abstract [en]

    A new kind of hybrid electrolyte with S2-/S-x(2-) and I- was invented, and the new hybrid system was demonstrated to outperform the well-known I-/I-3(-) redox system in DSCs. An efficiency of 9.1% was achieved in our lab under AM 1.5 illumination using the dye N719, considerably higher than the efficiency of 8.0% of the I-/I-3(-)-based electrolyte.

  • 32. Cong, Jiayan
    et al.
    Yang, Xichuan
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Iodine/iodide-free redox shuttles for liquid electrolyte-based dye-sensitized solar cells2012In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 5, no 11, p. 9180-9194Article, review/survey (Refereed)
    Abstract [en]

    Dye-sensitized solar cells have attracted intense academic interest over the past two decades. For a long time, the development of new redox systems has fallen far behind that of the sensitizing dyes and other materials. However, the field has received renewed attention recently. In particular, in 2011, the Gratzel group published a record DSC efficiency of 12.3% by using a new Co-complex-based electrolyte. In this review, we will provide an overview of iodine/iodide-free redox systems for liquid electrolytes, and reveal that the design of an efficient redox system should combine with appropriate sensitizing dyes which is the pivotal challenge for highly efficient DSCs.

  • 33. Desiraju, Gautam R.
    et al.
    Ho, P. Shing
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Legon, Anthony C.
    Marquardt, Roberto
    Metrangolo, Pierangelo
    Politzer, Peter
    Resnati, Giuseppe
    Rissanen, Kari
    Definition of the halogen bond (IUPAC Recommendations 2013)2013In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 85, no 8, p. 1711-1713Article in journal (Refereed)
    Abstract [en]

    This recommendation proposes a definition for the term "halogen bond", which designates a specific subset of the inter- and intramolecular interactions involving a halogen atom in a molecular entity.

  • 34. Ellis-Gibbings, Lilian
    et al.
    Johansson, Viktor
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Walsh, Rick B.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Quinton, Jamie S.
    Andersson, Gunther G.
    Formation of N719 Dye Multilayers on Dye Sensitized Solar Cell Photoelectrode Surfaces Investigated by Direct Determination of Element Concentration Depth Profiles2012In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 28, no 25, p. 9431-9439Article in journal (Refereed)
    Abstract [en]

    The structure of the dye layer adsorbed on the titania substrate in a dye-sensitized solar cell is of fundamental importance for the function of the cell, since it strongly influences the injection of photoelectrons from the excited dye molecules into the titania substrate. The adsorption isotherms of the N719 ruthenium-based dye were determined both with a direct method using the depth profiling technique neutral impact collision ion scattering spectroscopy (NICISS) and with the standard indirect solution depletion method. It is found that the dye layer adsorbed on the titania surface is laterally inhomogeneous in thickness and there is a growth mechanism already from low coverage levels involving a combination of monolayers and multilayers. It is also found that the amount of N719 adsorbed on the substrate depends on the titania structure. The present results show that dye molecules in dye-sensitized solar cells are not necessarily, as presumed, adsorbed as a self-assembled monolayer on the substrate.

  • 35. El-Zohry, Ahmed M.
    et al.
    Cong, Jiayan
    KTH.
    Karlsson, Martin
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zietz, Burkhard
    Ferrocene as a rapid charge regenerator in dye-sensitized solar cells2016In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 132, p. 360-368Article in journal (Refereed)
    Abstract [en]

    Using the reductive power of the ferrocene moiety (Fc), an ultrafast regeneration step via a covalent attachment of a Fc moiety to an organic triphenylamine-based dye (L1) when adsorbed on TiO2 is highlighted. Two modified dyes with one and two Fc moieties attached (L1Fc, and L1Fc2), respectively, were synthesized by addition to the L1 dye. These dyes have been studied spectroscopically using ultrafast transient absorption spectroscopy in the visible and the infrared (IR) regions. In acetonitrile, the results show an ultrafast excited state quenching of the modified dyes due to an expected electron transfer process from the Fc(s) to L1. Adsorbed onto TiO2, an electron transfer process is also detected from Fc to the oxidized dye (L1(+)). Despite the occurrence of an ultrafast regeneration step, the solar cell performance does not improve by the attachment of Fc(s) to the dye L1. Transient absorption measurements in the IR region revealed a fast electron recombination process to the Fc(+) moiety on an average time scale of ca. 300 ps, outcompeting the >12 ns process to L1(+). The reasons for the observed considerably faster recombination rate to Fc(+) than to L1(+) are discussed in detail. This study provides deep spectroscopic insights for such organic dyes utilized to afford ultrafast regeneration step without showing high performance in photovoltaic devices. In addition, this study will improve our understandings for the triangular relationship between the molecular design, electron kinetics, and the performance in photovoltaic devices. (C) 2016 Elsevier Ltd. All rights reserved.

  • 36.
    Eriksson, Margareta
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Andersson, Rolf
    Department of Chemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden .
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Reaction of SDS with ozone and OH radicals in aqueous solution2007In: Ozone: Science & engineering, ISSN 0191-9512, E-ISSN 1547-6545, Vol. 29, no 2, p. 131-138Article in journal (Refereed)
    Abstract [en]

    Ozone can be used as an antiseptic in cleaning systems. SDS (Sodium Dodecyl Sulfate) has proved to be a suitable surfactant in such systems. However, kinetic studies have showed that SDS reacts with ozone at high concentrations. In contrast, the natural decomposition of ozone to oxygen is retarded at low SDS concentrations. NMR spectroscopic analyses of SDS solutions being continuously treated with ozone and OH radicals, respectively, have been performed. H-1-, C-13-, COSY-, HMBC- and HSQC-NMR spectra were recorded showing that small carboxyl acids were formed at exposure to ozone. Randomly positioned carbonyl groups were also found along the hydrocarbon chain. However, the largest product was caused by direct reaction of SDS with ozone. The predominant product most likely is a SDS-peroxide. H-1-NMR spectra of the samples treated with OH radicals also show the formation of small carboxylic and carbonyl groups. However, there is no indication of oxidation of the sulphate group.

  • 37.
    Eriksson, Margareta
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Ozone decomposition in acidic solutionsManuscript (preprint) (Other academic)
  • 38.
    Eriksson, Margareta
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Östensson, Rasmus
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Bacteriological study of an aqueous solution with ozone and SDS or SDSperoxide2005In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336Article in journal (Other academic)
  • 39. Filatova, T. G.
    et al.
    Gurin, P. V.
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Kulbachinskii, V. A.
    Kuznetsov, A. N.
    Kytin, V. G.
    Lindsjo, M.
    Popovkin, B. A.
    Electronic structure, galvanomagnetic and magnetic properties of the bismuth subhalides Bi4I4 and Bi4Br42007In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 180, no 3, p. 1103-1109Article in journal (Refereed)
    Abstract [en]

    Two bismuth-rich subhalides, Bi4Br4 and Bi4I4, featuring extended quasi one-dimensional metallic fragments in their structures, have been investigated. The gas-phase technique of crystal growth has been refined for obtaining large (up to 5 mm long) single crystals. Electronic structure calculations on three-dimensional structures of both compounds have been performed (DFT level, hybrid B3LYP functional), predicting a semiconducting behavior for both compounds, with an indication of possible directional anisotropy of electric conductivity. Galvanomagnetic (resistance, magnetoresistance, Hall effect, thermopower) and magnetic (temperature and field dependence of magnetization) properties have been measured experimentally. Both compounds are found to be diamagnetic, room-temperature semiconductors with n-type conductivity. While Bi4Br4 demonstrates a typical case of one dimensionality, the difference in magnetoresistivity between Bi4Br4 and Bi4I4 indicates some weak interactions between isolated bismuth metallic fragments within the bismuth substructures.

  • 40.
    Fischer, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Pettersson, Henrik
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Boschloo, Gerrit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Gorlov, Mikhail
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Crystal formation involving 1-methylbenzimidazole in iodide/triiodide electrolytes for dye-sensitized solar cells2007In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 91, no 12, p. 1062-1065Article in journal (Refereed)
    Abstract [en]

    Nitrogen heterocyclic compounds, such as N-methylbenzimidazole (MBI), are commonly used as additives to electrolytes for dye-sensitized solar cells (DSCs), but the chemical transformation of additives in electrolyte solutions remains poorly understood. Solid crystalline compound (MBI)(6)(MBI-H+)(2)(I-)(I-3(-)) (1) was isolated from different electrolytes for DSCs containing MBI as additive. The crystal structure of I was determined by single-crystal X-ray diffraction. In the crystal structure, 1 contains neutral and protonated MBI fragments; iodide and triiodide anions form infinite chains along the crystallographic a-axis. The role of the solvent and additives in the crystallization process in electrolytes is discussed.

  • 41.
    Fischer, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sokka, Ilia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Belova, Liubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Synthesis, structure, and magnetic properties of some layered compounds based on long-chain sulfonium cations and complex cobalt and copper anions2013In: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 639, no 14, p. 2613-2617Article in journal (Refereed)
    Abstract [en]

    Two new materials of the composition ({CH3(CH2) 15(CH3)2S}+)2[CoBr 4]2- (1) and ({CH3(CH2) 15(CH3)2S}+)2[CuBr 4]2- (2 and 3), of which the latter exists in two polymorphs, were synthesized. The materials display the synthetically targeted structures, comprising of layers of complex metal ions and layers of long-chain sulfonium cations. The crystal structures of the materials were determined. The interlayer distances are around 24 Å, with metal-metal distances about 8 Å. The magnetic properties of 1 were investigated, and the material is paramagnetic. ({CH3(CH2)15(CH3) 2S}+)2[CuBr4]2 is polymorphic. Both polymorphs crystallize with triclinic symmetry.

  • 42.
    Forsberg, Kerstin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Resource recovery.
    Rodríguez Varela, Raquel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Martínez, Joaquin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Kloo, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Rasmuson, Åke C.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Processing of a rare earth element concentrate by hollow fibre supported liquid membrane extraction2017Conference paper (Refereed)
  • 43.
    Franchi, Daniele
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Inst Chem Organometall Cpds CNR ICCOM, I-50019 Sesto Fiorentino, Italy..
    Leandri, Valentina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Pizzichetti, Angela Raffaella Pia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Xu, Bo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH). Uppsala Univ, Ctr Mol Devices, Dept Chem, Div Phys Chem,Angstrom Lab, SE-75120 Uppsala, Sweden..
    Hao, Yan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Zhang, Wei
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sloboda, Tamara
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Svanstrom, Sebastian
    Uppsala Univ, Dept Phys & Astron, Div Xray Photon Sci, SE-75120 Uppsala, Sweden..
    Cappel, Ute B.
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Westlake Univ, Ctr Artificial Photosynth Solar Fuels, Sch Sci, Hangzhou 310024, Peoples R China..
    Gardner, James M.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Effect of the Ancillary Ligand on the Performance of Heteroleptic Cu(I) Diimine Complexes as Dyes in Dye-Sensitized Solar Cells2022In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, no 2, p. 1460-1470Article in journal (Refereed)
    Abstract [en]

    A series of heteroleptic Cu(I) diimine complexes with different ancillary ligands and 6,6'-dimethyl-2,2'-bipyridine-4,4'-dibenzoic acid (dbda) as the anchoring ligand were selfassembled on TiO2 surfaces and used as dyes for dye-sensitized solar cells (DSSCs). The binding to the TiO2 surface was studied by hard X-ray photoelectron spectroscopy for a brominecontaining complex, confirming the complex formation. The performance of all complexes was assessed and rationalized on the basis of their respective ancillary ligand. The DSSC photocurrent-voltage characteristics, incident photon-to-current conversion efficiency (IPCE) spectra, and calculated lowest unoccupied molecular orbital (LUMO) distributions collectively show a push-pull structural dye design, in which the ancillary ligand exhibits an electron-donating effect that can lead to improved solar cell performance. By analyzing the optical properties of the dyes and their solar cell performance, we can conclude that the presence of ancillary ligands with bulky substituents protects the Cu(I) metal center from solvent coordination constituting a critical factor in the design of efficient Cu(I)-based dyes. Moreover, we have identified some components in the I-/I-3(-)-based electrolyte that causes dissociation of the ancillary ligand, i.e., TiO2 photoelectrode bleaching. Finally, the detailed studies on one of the dyes revealed an electrolyte-dye interaction, leading to a dramatic change of the dye properties when adsorbed on the TiO2 surface.

  • 44.
    Fredin, Kristofer
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Gorlov, M.
    IVF Industrial Research and Development Corporation, Mölndal.
    Pettersson, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Boschloo, Gerrit
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    On the influence of anions in binary ionic liquid electrolytes for monolithic dye-sensitized solar cells2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 35, p. 13261-13266Article in journal (Refereed)
    Abstract [en]

    Five ion c liquids (ILs) of the general formula Im(+)A(-), where Im(+) = I -methyl-3-n-butyl-imidazolium, A(-) = I- (1), BF4- (2), SCN- (3), CF3CO2- (4), and CF(3)S0(3)(-) (5), were used in electrolytes for dye-sensitized monolithic solar cells. The properties of the electrolytes and various characteristics of the solar cell performance, such as electron transport and electron lifetime, were studied. The composition of the binary electrolytes, i.e., the different anions, have a significant effect on the viscosity, but only a modest effect of the measured diffusior. coefficient for triiodide. No significant effect of the electrolyte composition on the electron transport time in the mesoporous TiO2 film was found, while there was a pronounced effect on the electron lifetime. Monolithic solar cells with thiocyanate, IL 3, showed overall light-to-electricity conversion efficiency up to 5.6% in 250 W m(-2) simulated sunlight and have promising stability.

  • 45.
    Gabrielsson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Eriksson, Susanna K.
    Gao, Jiajia
    Chen, Hong
    Li, Fusheng
    Oscarsson, Johan
    Sun, Juliang
    Resmo, Håkan
    Kloo, lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hagfeldt, Anders
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Dipicolinic Acid: A Strong Anchoring Group with Tunable Redoxand Spectral Behavior for Stable Dye-Sensitized Solar CellsManuscript (preprint) (Other academic)
  • 46.
    Gabrielsson, Erik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Uppsala University, Sweden.
    Eriksson, Susanna K.
    Gao, Jiajia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Chen, Hong
    Li, Fusheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Oscarsson, Johan
    Sun, Junliang
    Rensmo, Håkan
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Hagfeldt, Anders
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Dalian University of Technology (DUT), China.
    Dipicolinic acid: a strong anchoring group with tunable redox and spectral behavior for stable dye-sensitized solar cells2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 18, p. 3858-3861Article in journal (Refereed)
    Abstract [en]

    Dipicolinic acidwas investigated as a new anchoring group for DSSCs. A pilot dye (PD2) bearing this new anchoring group was found to adsorb significantly stronger to TiO2 than its cyanoacrylic acid analogue. The electrolyte composition was found to have a strong effect on the photoelectrochemical properties of the adsorbed dye in the device, allowing the dye LUMO energy to be tuned by 0.5 eV. Using a pyridine-free electrolyte, panchromatic absorption of the dye on TiO2 extending to 900 nm has been achieved. Solar cells using PD2 and a Co(bpy)(3) based electrolyte showed unique stability under simulated sunlight and elevated temperatures.

  • 47.
    Gamstedt, Helene
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Hagfeldt, Anders
    Physical Chemistry, Uppsala University.
    Kloo, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Photoelectrochemical studies of ionic liquid-containing solar cells sensitized with different polypyridyl-ruthenium complexes2009In: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 28, no 4, p. 757-762Article in journal (Refereed)
    Abstract [en]

    The efficiency of dye-sensitized nanocrystalline solar cells containing ionic liquids, composed of organic sulfonium or imidazolium iodides, or a standard organic-liquid-based electrolyte was studied, while using sensitizers based on different polypyridyl-ruthenium complexes. The dyes N-719, [cis-Ru(II)(H(2)dcbpy)(2)(NCS)(2)(TBA)(2)] and Z-907, [cis-Ru(II)(H(2)dcbpy)(dnbpy)(NCS)(2), Z-907 having a more hydrophobic character. as well as a bidentate beta-diketonato complex, [(dcbpy)(2)Ru(acetylacetonate)]Cl-, was studied. Solar cells sensitized with the dye N-719 were more efficient than the Z-907 cells, for all electrolytes studied. Adding a co-adsorbent, the amphiphilic hexadecylmalonic acid (HDMA), to Z-907 solar cells containing an organic-liquid electrolyte resulted in increased overall light-to-electricity conversion efficiencies, from 3.7% to 4.0%, (100 W m(-2), AM 1.5). Possibly, this is caused by an insulating hydrophobic barrier formed to suppress unwanted electron losses. By applying TiO2 (P25) nanoparticles, assumed to support electron transfer reactions, to the organic-liquid electrolyte, the conversion efficiency was increased from 4.1% to 4.6% (100 W m(-2), AM 1.5). In 1000 W m(-2) illumination, the highest overall short-circuit current density, 9.3 mA cm(-2), was achieved with the N-719 sensitized cells, with the TiO2 nanocomposite-containing organic-liquid-based electrolyte. For solar cells sensitized with N-719, Z-907 or the beta-diketonato complex, and containing imidazolium or sulfonium iodide ionic liquids, no improvements of the overall conversion efficiency could be noticed at addition of HDMA to the dye or nanoparticles to the electrolyte.

  • 48.
    Gao, Jiajia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bhagavathiachari, Muthuraaman
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Long-term stability for cobalt-based dye-sensitized solar cells obtained by electrolyte optimization2014In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, no 47, p. 6249-6251Article in journal (Refereed)
    Abstract [en]

    A significant improvement in the long-term stability for cobalt-based dye-sensitized solar cells (DSCs) under light-soaking conditions has been achieved by optimization of the composition of tris(2,2'-bipyridine) Co(II)/Co(III) electrolytes. The effects of component exchanges and changes were also studied during the optimization process.

  • 49.
    Gao, Jiajia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    El-Zohry, Ahmed M.
    Uppsala Univ, Angstrom Lab, Dept Chem, Box 523, SE-75120 Uppsala, Sweden..
    Trilaksana, Herri
    Flinders Univ S Australia, Flinders Ctr NanoScale Sci & Technol CNST, Adelaide, SA 5042, Australia..
    Gabrielsson, Erik
    Dyenamo AB, Greenhouse Labs, Tekn Ringen 38A, SE-11428 Stockholm, Sweden..
    Leandri, Valentina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Ellis, Hanna
    Uppsala Univ, Angstrom Lab, Dept Chem, Box 523, SE-75120 Uppsala, Sweden..
    D'Amario, Luca
    Uppsala Univ, Angstrom Lab, Dept Chem, Box 523, SE-75120 Uppsala, Sweden..
    Safdari, Majid
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Gardner, James M.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Andersson, Gunther
    Flinders Univ S Australia, Flinders Ctr NanoScale Sci & Technol CNST, Adelaide, SA 5042, Australia..
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Light-Induced Interfacial Dynamics Dramatically Improve the Photocurrent in Dye-Sensitized Solar Cells: An Electrolyte Effect2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 31, p. 26241-26247Article in journal (Refereed)
    Abstract [en]

    A significant increase in the photocurrent generation during light soaking for solar cells sensitized by the triphenylamine-based D-pi-A organic dyes (PD2 and LEG1) and mediated by cobalt bipyridine redox complexes has been observed and investigated. The crucial role of the electrolyte has been identified in the performance improvement. Control experiments based on a pretreatment strategy reveals TBP as the origin. The increase in the current and IPCE has been interpreted by the interfacial charge-transfer kinetics studies. A slow component in the injection kinetics was exposed for this system. This change explains the increase in the electron lifetime and collection efficiency. Photoelectron spectroscopic measurements show energy shifts at the dye/TiO2 interface, leading us to formulate a hypothesis with respect to an electrolyte induced dye reorganization at the surface.

  • 50.
    Gao, Jiajia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fischer, Andreas C.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Crystallography as Forensic Tool for Understanding Electrolyte Degradation in Dye-sensitized Solar Cells2017In: CHEMISTRYSELECT, ISSN 2365-6549, Vol. 2, no 4, p. 1675-1680Article in journal (Refereed)
    Abstract [en]

    The precipitation of solid compounds from model electrolytes for liquid dye-sensitized solar cells has a story to tell regarding decomposition processes to be expected in such systems. Of course, the crystal lattice energy for a specific crystalline compounds plays a role in what compound that will eventually precipitate, but the compounds nevertheless serve as indicators for what type of processes that take place in the solar cell electrolytes upon ageing. From the compounds isolated in this study we learn that both ligand exchange processes, double-salt precipitation and oxidation are degradation processes that should not be overlooked when formulating efficient and stable electrolytes for this type of electrochemical system.

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