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  • 151. Hetterscheid, D. G. H.
    et al.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Water oxidation2014In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 4, p. 571-572Article in journal (Refereed)
  • 152. Hou, J.
    et al.
    Cao, S.
    Wu, Y.
    Liang, F.
    Sun, Y.
    Lin, Z.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    Simultaneously efficient light absorption and charge transport of phosphate and oxygen-vacancy confined in bismuth tungstate atomic layers triggering robust solar CO2 reduction2017In: Nano Energy, ISSN 2211-2855, Vol. 32, p. 359-366Article in journal (Refereed)
    Abstract [en]

    The fundamental catalytic limitations for the photoreduction of CO2 still remain: low efficiency, poor charge transport and short lifetime of catalysts. To address the critical challenges, an efficient strategy based on spatial location engineering of phosphate (PO4) and oxygen-vacancy (Vo) confined in Bi2WO6 (BWO) atomic layers is employed to establish and explore an intimate functional link between the electronic structures and activities of Vo-PO4-BWO layers. Both theoretical and experimental results reveal, the Vo-PO4-BWO layers not only narrow the band gap from the UV to visible-light region but also reduce the resistance. The time-resolved photoluminescence decay spectra exhibit the increasing carrier lifetime for Vo-PO4-BWO layers, indicating the improved charge separation and transfer efficiency. As expected, the Vo-PO4-BWO layers with the simultaneously efficient light absorption and charge transport properties achieve much higher methanol formation rate of 157 μmol g-1 h-1, over 2 and 262 times larger than that of BWO atomic layers and bulk BWO. This work may reveal that the light absorption and spatial charge transport over atomic layers could benefit CO2 conversion and shed light on the design principles of efficient photocatalysts towards solar conversion applications.

  • 153. Hou, J.
    et al.
    Cao, S.
    Wu, Y.
    Liang, F.
    Ye, L.
    Lin, Z.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Technical Institute of Physics and Chemistry, China.
    Perovskite-based nanocubes with simultaneously improved visible-light absorption and charge separation enabling efficient photocatalytic CO2 reduction2016In: Nano Energy, ISSN 2211-2855, Vol. 30, p. 59-68Article in journal (Refereed)
    Abstract [en]

    Finding an ideal model to disclose the role upon tuning band structure and charge separation of wide-bandgap perovskite semiconductors by introducing suitable heteroatoms remains a huge challenge in photocatalysis. Herein, we propose an efficient pathway to increase the light absorption and charge separation for nitrogen and oxygen-vacancy confined in sodium tantalate nanocubes (Vo-NaTaON) and nitrogen-doped graphene quantum dots (N-GQDs) grafted Vo-NaTaON nanocubes by solution-etching-induced phase-transition and in-situ reduction strategies. First-principles calculations demonstrate that the simultaneous incorporation of nitrogen and oxygen-vacancy in sodium tantalate can effectively regulate the electronic structure of sodium tantalate. The analysis of UV–vis spectra and electron paramagnetic resonance reveal that the synergistic contribution of nitrogen and oxygen-vacancy endows the wide-bandgap perovskites tuning the band absorption region from UV (315 nm) to visible regime beyond 600 nm. As expected, an optimized Vo-NaTaON catalyst was developed, exhibiting superior broad spectrum photochemical reduction of CO2 to fuels. Moreover, N-GQDs/Vo-NaTaON heterojunctions further improve the broad spectrum CO2 photoreduction due to the synergetic catalytic effect of simultaneously improved light-absorption and charge separation. This work may open up more opportunities in the design of efficient photocatalysts for applications in solar photochemical conversion.

  • 154.
    Hou, Jungang
    et al.
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Cao, Shuyan
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Yiqing
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Wu, Yunzhen
    DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Liang, Fei
    Chinese Acad Sci, Tech Inst Phys & Chem, Beijing 100190, Peoples R China..
    Lin, Zheshuai
    Chinese Acad Sci, Tech Inst Phys & Chem, Beijing 100190, Peoples R China..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Atomically Thin Mesoporous In2O3-x/In2S3 Lateral Heterostructures Enabling Robust Broadband-Light Photo-Electrochemical Water Splitting2018In: Advanced Energy Materials, ISSN 1614-6832, Vol. 8, no 9, article id 1701114Article in journal (Refereed)
    Abstract [en]

    Atomically thin 2D heterostructures have opened new realms in electronic and optoelectronic devices. Herein, 2D lateral heterostructures of mesoporous In2O3-x/In2S3 atomic layers are synthesized through the in situ oxidation of In2S3 atomic layers by an oxygen plasma-induced strategy. Based on experimental observations and theoretical calculations, the prolonged charge carrier lifetime and increased electron density reveal the efficient photoexcited carrier transport and separation in the In2O3-x/In2S3 layers by interfacial bonding at the atomic level. As expected, the synergistic structural and electronic modulations of the In2O3-x/In2S3 layers generate a photocurrent of 1.28 mA cm(-2) at 1.23 V versus a reversible hydrogen electrode, nearly 21 and 79 times higher than those of the In2S3 atomic layers and bulk counterpart, respectively. Due to the large surface area, abundant active sites, broadband-light harvesting ability, and effective charge transport pathways, the In2O3-x/In2S3 layers build efficient pathways for photoexcited charge in the 2D semiconductive channels, expediting charge transport and kinetic processes and enhancing the robust broadband-light photo-electrochemical water splitting performance. This work paves new avenues for the exploration and design of atomically thin 2D lateral heterostructures toward robust photo-electrochemical applications and solar energy utilization.

  • 155. Hou, Jungang
    et al.
    Cao, Shuyan
    Wu, Yunzhen
    Gao, Zhanming
    Liang, Fei
    Sun, Yiqing
    Lin, Zheshuai
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Inorganic Colloidal Perovskite Quantum Dots for Robust Solar CO2 Reduction2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 40, p. 9481-9485Article in journal (Refereed)
    Abstract [en]

    Inorganic perovskite quantum dots as optoelectronic materials have attracted enormous attention in light-harvesting and emitting devices. However, photocatalytic conversion based on inorganic perovskite halides has not been reported. Here, we have synthesized colloidal quantum dots (QDs, 3-12 nm) of cesium lead halide perovskites (CsPbBr3) as a new type of photocatalytic material. The band gap energies and photoluminescence (PL) spectra are tunable over the visible spectral region according to quantum size effects on an atomic scale. The increased carrier lifetime revealed by time-resolved PL spectra, indicates the efficient electron-hole separation and transfer. As expected, the CsPbBr3 QDs with high selectivity of greater than 99% achieve an efficient yield of 20.9 mmolg(-1) towards solar CO2 reduction. This work has opened a new avenue for inorganic colloidal perovskite materials as efficient photocatalysts to convert CO2 into valuable fuels.

  • 156. Hou, Jungang
    et al.
    Sun, Yiqing
    Cao, Shuyan
    Wu, Yunzhen
    Chen, Hong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic 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. KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Graphene Dots Embedded Phosphide Nanosheet-Assembled Tubular Arrays for Efficient and Stable Overall Water Splitting2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 29, p. 24600-24607Article in journal (Refereed)
    Abstract [en]

    Bifunctional electrocatalysts are highly desired for overall water splitting. Herein, the design and fabrication of three-dimensional (3D) hierarchical earth-abundant transition bimetallic phosphide arrays constructed by one-dimensional tubular array that was derived from assembling two-dimensional nanosheet framework has been reported by tailoring the Co/Ni ratio and tunable morphologies, and zero-dimensional (0D) graphene dots were embedded on Co-Ni phosphide matrix to construct 0D/2D tubular array as a highly efficient electrode in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). On the basis of advanced merits, such as the high surface-active sites, well-dispersed graphene dots, and enhanced electron transfer capacity as well as the confinement effect of the graphene dots on the nanosheets, the integrated GDs/Co0.8Ni0.2P tubular arrays as anode and cathode exhibit excellent OER and HER performance. By use of GDs/Co0.8Ni0.2 arrays in the two-electrode setup of the device, a remarkable electrocatalytic performance for full water splitting has been achieved with a high current density of 10 mA cm-2 at 1.54 V and outstanding long-term operation stability in an alkaline environment, indicating a promising system based on nonprecious-metal electrocatalysts toward potential practical devices of overall water splitting.

  • 157.
    Hou, Jungang
    et al.
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Yiqing
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Li, Zhuwei
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Zhang, Bo
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Cao, Shuyan
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Wu, Yunzhen
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Gao, Zhanming
    DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. DUT, Inst Energy Sci & Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China.
    Electrical Behavior and Electron Transfer Modulation of Nickel-Copper Nanoalloys Confined in Nickel-Copper Nitrides Nanowires Array Encapsulated in Nitrogen-Doped Carbon Framework as Robust Bifunctional Electrocatalyst for Overall Water Splitting2018In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 37, article id 1803278Article in journal (Refereed)
    Abstract [en]

    Probing robust electrocatalysts for overall water splitting is vital in energy conversion. However, the catalytic efficiency of reported catalysts is still limited by few active sites, low conductivity, and/or discrete electron transport. Herein, bimetallic nickel-copper (NiCu) nanoalloys confined in mesoporous nickel-copper nitride (NiCuN) nanowires array encapsulated in nitrogen-doped carbon (NC) framework (NC-NiCu-NiCuN) is constructed by carbonization-/nitridation-induced in situ growth strategies. The in situ coupling of NiCu nanoalloys, NiCuN, and carbon layers through dual modulation of electrical behavior and electron transfer is not only beneficial to continuous electron transfer throughout the whole system, but also promotes the enhancement of electrical conductivity and the accessibility of active sites. Owing to strong synergetic coupling effect, such NC-NiCu-NiCuN electrocatalyst exhibits the best hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance with a current density of 10 mA cm(-2) at low overpotentials of 93 mV for HER and 232 mV for OER, respectively. As expected, a two-electrode cell using NC-NiCu-NiCuN is constructed to deliver 10 mA cm(-2) water-splitting current at low cell voltage of 1.56 V with remarkable durability over 50 h. This work serves as a promising platform to explore the design and synthesis of robust bifunctional electrocatalyst for overall water splitting.

  • 158. Hou, Jungang
    et al.
    Sun, Yiqing
    Wu, Yunzhen
    Cao, Shuyan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Promoting Active Sites in Core-Shell Nanowire Array as Mott-Schottky Electrocatalysts for Efficient and Stable Overall Water Splitting2018In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 4, article id 1704447Article in journal (Refereed)
    Abstract [en]

    Developing earth-abundant, active, and robust electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a vital challenge for efficient conversion of sustainable energy sources. Herein, metal-semiconductor hybrids are reported with metallic nanoalloys on various defective oxide nanowire arrays (Cu/CuOx, Co/CoOx, and CuCo/CuCoOx) as typical Mott-Schottky electrocatalysts. To build the highway of continuous electron transport between metals and semiconductors, nitrogen-doped carbon (NC) has been implanted on metal-semiconductor nanowire array as core-shell conductive architecture. As expected, NC/CuCo/CuCoOx nanowires arrays, as integrated Mott-Schottky electrocatalysts, present an overpotential of 112 mV at 10 mA cm(-2) and a low Tafel slope of 55 mV dec(-1) for HER, simultaneously delivering an overpotential of 190 mV at 10 mA cm(-2) for OER. Most importantly, NC/CuCo/CuCoOx architectures, as both the anode and the cathode for overall water splitting, exhibit a current density of 10 mA cm(-2) at a cell voltage of 1.53 V with excellent stability due to high conductivity, large active surface area, abundant active sites, and the continuous electron transport from prominent synergetic effect among metal, semiconductor, and nitrogen-doped carbon. This work represents an avenue to design and develop efficient and stable Mott-Schottky bifunctional electrocatalysts for promising energy conversion.

  • 159. Hou, Jungang
    et al.
    Wu, Yunzhen
    Cao, Shuyan
    Liang, Fei
    Lin, Zheshuai
    Gao, Zhanming
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China.
    In Situ Phase-Induced Spatial Charge Separation in Core-Shell Oxynitride Nanocube Heterojunctions Realizing Robust Solar Water Splitting2017In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 7, no 17, article id 1700171Article in journal (Refereed)
    Abstract [en]

    Efficient spatial charge separation is critical for solar energy conversion over solid photocatalysts. The development of efficient visible-light photocatalysts has been of immense interest, but with limited success. Here, multiband core-shell oxynitride nanocube heterojunctions composed of a tantalum nitride (Ta3N5) core and nitrogen-doped sodium tantalate (NaTaON) shell have been constructed via an in situ phase-induced etching chemical strategy. The photocatalytic water splitting performance of sub-20-nm Ta3N5@NaTaON junctions exhibits an extraordinarily high photocatalytic activity toward oxygen and hydrogen evolution. Most importantly, the combined experimental results and theoretical calculations reveal that the strong interfacial Ta-O-N bonding connection as a touchstone among Ta3N5@NaTaON junctions provides a continuous charge transport pathway rather than a random charge accumulation. The prolonged photoexcited charge carrier lifetime and suitable band matching between the Ta3N5 core and NaTaON shell facilitate the separation of photoinduced electron-hole pairs, accounting for the highly efficient photocatalytic performance. This work establishes the use of (oxy)nitride heterojunctions as viable photocatalysts for the conversion of solar energy into fuels.

  • 160. Hou, Jungang
    et al.
    Wu, Yunzhen
    Cao, Shuyan
    Sun, Yiqing
    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.
    Active Sites Intercalated Ultrathin Carbon Sheath on Nanowire Arrays as Integrated Core-Shell Architecture: Highly Efficient and Durable Electrocatalysts for Overall Water Splitting2017In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 13, no 46, article id UNSP 1702018Article in journal (Refereed)
    Abstract [en]

    The development of active bifunctional electrocatalysts with low cost and earth-abundance toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a great challenge for overall water splitting. Herein, metallic Ni4Mo nanoalloys are firstly implanted on the surface of NiMoOx nanowires array (NiMo/NiMoOx) as metal/metal oxides hybrid. Inspired by the superiority of carbon conductivity, an ultrathin nitrogen-doped carbon sheath intercalated NiMo/NiMoOx (NC/NiMo/NiMoOx) nanowires as integrated core-shell architecture are constructed. The integrated NC/NiMo/NiMoOx array exhibits an overpotential of 29 mV at 10 mA cm(-2) and a low Tafel slope of 46 mV dec(-1) for HER due to the abundant active sites, fast electron transport, low charge-transfer resistance, unique architectural structure and synergistic effect of carbon sheath, nanoalloys, and oxides. Moreover, as OER catalysts, the NC/NiMo/NiMoOx hybrids require an overpotential of 284 mV at 10 mA cm(-2). More importantly, the NC/NiMo/NiMoOx array as a highly active and stable electrocatalyst approaches approximate to 10 mA cm(-2) at a voltage of 1.57 V, opening an avenue to the rational design and fabrication of the promising electrode materials with architecture structures toward the electrochemical energy storage and conversion.

  • 161.
    Hou, Jungang
    et al.
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Zhang, Bo
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Li, Zhuwei
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Cao, Shuyan
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Sun, Yiqing
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Wu, Yunzhen
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Gao, Zhanming
    DUT, Inst Energy Sci & Technol, KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    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.
    Vertically Aligned Oxygenated-CoS2-MoS2 Heteronanosheet Architecture from Polyoxometalate for Efficient and Stable Overall Water Splitting2018In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 5, p. 4612-4621Article in journal (Refereed)
    Abstract [en]

    To achieve efficient conversion of renewable energy sources through water splitting, low-cost, earth-abundant, and robust electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are required. Herein, vertically aligned oxygenated-CoS2-MoS2 (O-CoMoS) heteronanosheets grown on flexible carbon fiber cloth as bifunctional electrocatalysts have been produced by use of the Anderson-type (NH4)(4)[CoIIMo(6)O(2)4H(6)]center dot 6H(2)O polyoxometalate as bimetal precursor. In comparison to different O-FeMoS, O-NiMoS, and MoS2 nanosheet arrays, the O-CoMoS heteronanosheet array exhibited low overpotentials of 97 and 272 mV to reach a current density of 10 mA cm(-2) in alkaline solution for the HER and OER, respectively. Assembled as an electrolyzer for overall water splitting, O-CoMoS heteronanosheets as both the anode and cathode deliver a current density of 10 mA cm(-2) at a quite low cell voltage of 1.6 V. This O-CoMoS architecture is highly advantageous for a disordered structure, exposure of active heterointerfaces, a "highway" of charge transport on two-dimensional conductive channels, and abundant active catalytic sites from the synergistic effect of the heterostructures, accomplishing a dramatically enhanced performance for the OER, HER, and overall water splitting. This work represents a feasible strategy to explore efficient and stable bifunctional bimetal sulfide electrocatalysts for renewable energy applications.

  • 162. Hu, M.
    et al.
    Yu, Z.
    Li, J.
    Jiang, X.
    Lai, J.
    Yang, X.
    Wang, M.
    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.
    Low-cost solution-processed digenite Cu9S5 counter electrode for dye-sensitized solar cells2017In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 61, p. 38452-38457Article in journal (Refereed)
    Abstract [en]

    The development of low-cost alternatives to the commonly used but expensive platinum (Pt) catalyst in dye-sensitized solar cells (DSSCs) is important from a commercial point of view. In this work, Cu9S5 nanocrystalline film is fabricated directly onto a F-doped SnO2 (FTO) substrate by a solution-processed spin-coating method with low temperature post-treatment at 250 °C and it is further explored as a counter electrode (CE) material in DSSCs. The results from cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) disclose that Cu9S5 film exhibits a higher catalytic ability for the state-of-the-art cobalt(ii/iii) tris(bipyridyl) ([Co(bpy)3]2+/3+) redox system as compared to the widely used iodine-based electrolyte. Consequently, the DSSC devices based on the cobalt complex redox shuttles show a power conversion efficiency (PCE) of 5.7% measured at 100 mW cm-2 illumination (AM 1.5G), which is substantially higher than that of the iodine-based counterpart (3.9%). This has been the first presentation for the application of digenite copper sulfides as an electrocatalyst for the [Co(bpy)3]2+/3+ redox system in DSSCs. The present finding represents a promising solution for the development of alternative cost-effective CE materials for DSSCs in the future.

  • 163.
    Hu, Maowei
    et al.
    Dalian Univ Technol, Inst Artificial Photosynth, Inst Energy Sci & Technol, State Key Lab Fine Chem,DUT KTH Joint Educ & Res, Dalian 116024, Peoples R China..
    Shen, Junyu
    Dalian Univ Technol, Inst Artificial Photosynth, Inst Energy Sci & Technol, State Key Lab Fine Chem,DUT KTH Joint Educ & Res, Dalian 116024, Peoples R China..
    Yu, Ze
    Dalian Univ Technol, Inst Artificial Photosynth, Inst Energy Sci & Technol, State Key Lab Fine Chem,DUT KTH Joint Educ & Res, Dalian 116024, Peoples R China..
    Liao, Rong-Zhen
    Huazhong Univ Sci & Technol, Sch Chem & Chem Engn, Key Lab Mat Chem Energy Convers & Storage, Minist Educ, Wuhan 430074, Hubei, Peoples R China..
    Gurzadyan, Gagik G.
    Dalian Univ Technol, Inst Artificial Photosynth, Inst Energy Sci & Technol, State Key Lab Fine Chem,DUT KTH Joint Educ & Res, Dalian 116024, Peoples R China..
    Yang, Xichuan
    Dalian Univ Technol, Inst Artificial Photosynth, Inst Energy Sci & Technol, State Key Lab Fine Chem,DUT KTH Joint Educ & Res, Dalian 116024, Peoples R China..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Wang, Mei
    Dalian Univ Technol, Inst Artificial Photosynth, Inst Energy Sci & Technol, State Key Lab Fine Chem,DUT KTH Joint Educ & Res, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Dalian Univ Technol, Inst Artificial Photosynth, Inst Energy Sci & Technol, State Key Lab Fine Chem,DUT KTH Joint Educ & Res, Dalian 116024, Peoples R China.
    Efficient and Stable Dye-Sensitized Solar Cells Based on a Tetradentate Copper(II/I) Redox Mediator2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 36, p. 30409-30416Article in journal (Refereed)
    Abstract [en]

    The identification of an efficient and stable redox mediator is of paramount importance for commercialization of dye-sensitized solar cells (DSCs). Herein, we report a new class of copper complexes containing diamine-dipyridine tetradentate ligands (L1 = N,N'-dibenzyl-N,N'-bis-(pyridin-2-ylmethyl)ethylenediamine; L2 = N,N'-dibenzyl-N,N'-bis (6-methyl-pyridin-2-ylmethyl)ethylenediamine) as redox mediators in DSCs. Devices constructed with [Cu(L2)](2+/+) redox couple afford an impressive power conversion efficiency (PCE) of 9.2% measured under simulated one sun irradiation (100 mW cm(-2), AM 1.5G), which is among the top efficiencies reported thus far for DSCs with copper complex-based redox mediators. Remarkably, the excellent air, photo, and electrochemical stability of the [Cu(L2)](2+/+) complexes renders an outstanding long-term stability of the whole DSC device, maintaining similar to 90% of the initial efficiency over 500 h under continuous full sun irradiation. This work unfolds a new platform for developing highly efficient and stable redox mediators for large-scale application of DSCs.

  • 164. Hu, Minggang
    et al.
    Wang, Mei
    Zhang, Peili
    Jin, Kun
    Chen, Yuee
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Polymerization of rac-lactide catalyzed by group 4 metal complexes containing chiral N atoms2012In: Polymer Bulletin, ISSN 0170-0839, E-ISSN 1436-2449, Vol. 68, no 7, p. 1789-1799Article in journal (Refereed)
    Abstract [en]

    The hydroxyl- and phenoxy-bridged dinuclear zirconium and hafnium complexes, 1 and 2, containing a chiral N atom in the N2O2 ligand (H2L = 2-(((2-pyridylmethyl)(2-hydroxyphenyl)amino)methyl)-4,6-di(tert-butyl)ph enol) were used as catalysts for the ring-opening polymerization of rac-lactide. Experiments prove that 1 and 2 are living and controlled catalytic systems with activity up to 3.25 g(pol) mmol(ini) (-1) h(-1). The isotactic-rich polylactides in a narrow polydispersity (M (w)/M (n) = 1.01-1.13) were produced with enantiomeric complexes 1 and 2 (P (m) = 0.65-0.73). The kinetic studies show a first-order dependency in both monomer and initiator. The initiation mechanism is discussed on the basis of the MALDI-TOF MS and H-1 NMR spectra of the rac-LA oligomer prepared by 1.

  • 165. Hu, Minggang
    et al.
    Wang, Mei
    Zhang, Peili
    Wang, Lin
    Zhu, Fangjun
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Preparation and structure of an enantiomeric water-bridged dinuclear indium complex containing two homochiral N atoms and its performance as an initiator in polymerization of rac-lactide2010In: Inorganic Chemistry Communications, ISSN 1387-7003, E-ISSN 1879-0259, Vol. 13, no 8, p. 968-971Article in journal (Refereed)
    Abstract [en]

    A novel dinuclear indium complex (1) containing a sole water bridge was prepared from the reaction of InCl3 with an unsymmetric N2O2-ligand and the molecular structure of the complex 1 was determined. The X-ray crystallography data show that the dinuclear complex possesses two homochiral N atoms, namely, N(R)N(R) and N(S)N(S) enantiomers. Complex 1 was used as initiator for ring-opening polymerization of rac-lactide, giving heterotactic-rich polylactide (P-r = 0.63-0.69) with narrow polydispersities (1.13-1.31).

  • 166. Hu, Minggang
    et al.
    Wang, Mei
    Zhu, Hongjun
    Zhang, Lu
    Zhang, Hui
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Preparation and structures of enantiomeric dinuclear zirconium and hafnium complexes containing two homochiral N atoms, and their catalytic property for polymerization of rac-lactide2010In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 39, no 18, p. 4440-4446Article in journal (Refereed)
    Abstract [en]

    The hydroxy-and phenoxy-bridged dinuclear zirconium and hafnium complexes 2 and 3 of an amine-pyridine-bis(phenolate) ligand (H2L) were prepared from the reaction of Na2L and ZrCl4 in the presence of 0.5 equiv of water in THF, while the reaction of H2L with NaH and then with ZrCl4 in the freshly distilled THF gave an eight-coordinate bis(homoleptic) mononuclear complex L2Zr (1). Two homochiral N atoms were created in each complex upon coordination of the unsymmetric tertiary amine ligands to the metal centers. Enantiomeric dinuclear complexes 2 and 3 both undergo spontaneous resolution during crystallization. The molecular structure of each enantiomer of 2 and 3, as well as the structure of 1, was determined by X-ray analysis and the circular dichroism spectra of N(R)N(R)-2 and N(S)N(S)-2 were studied. The racemates of 2 and 3 catalyzed controlled polymerization of rac-lactide in terms of the linearity of molecular weight versus conversion, forming isotactic-rich polylactide in high yields with a narrow polydispersity.

  • 167.
    Hua, Yong
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Liu, Peng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Li, Yuanyuan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Sun, Licheng
    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.
    Composite Hole-Transport Materials Based on a Metal-Organic Copper Complex and Spiro-OMeTAD for Efficient Perovskite Solar Cells2018In: SOLAR RRL, ISSN 2367-198X, Vol. 2, no 5, article id UNSP 1700073Article in journal (Refereed)
    Abstract [en]

    Spiro-OMeTAD has been the most commonly used hole-transport material in perovskite solar cells. However, this material shows intrinisic drawbacks, such as low hole mobility and conductivity in its pristine form, as well as self-aggregation when deposited as thin film. These are not beneficial properties for efficient hole transport and extraction. In order to address these issues, we have designed a new type of composite hole-transport materials based on a new metal-organic copper complex (CuH) and Spiro-OMeTAD. The incorporation of the molecularly bulky HTM CuH into the Spiro-OMeTAD material efficiently improves the hole mobility and suppresses the aggregation in the Spiro-OMeTAD film. As a result, the conversion efficiencies obtained for perovskite solar cells based on the composite HTM system reached as high as 18.83%, which is superior to solar cells based on the individual hole-transport materials CuH (15.75%) or Spiro-OMeTAD (14.47%) under the same working conditions. These results show that composite HTM systems may constitute an effective strategy to further improve the efficiency of perovskite solar cells.

  • 168.
    Hua, Yong
    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.
    Xu, Bo
    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.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Chen, Hong
    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, Applied Physical Chemistry.
    Cheng, Ming
    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.
    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.
    High conductivity Ag-based metal organic complexes as dopant-free hole-transport materials for perovskite solar cells with high fill factors2016In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 7, no 4, p. 2633-2638Article in journal (Refereed)
    Abstract [en]

    Hole-transport materials (HTMs) play an important role as hole scavenger materials in the most efficient perovskite solar cells (PSCs). Here, for the first time, two Ag-based metal organic complexes (HA1 and HA2) are employed as a new class of dopant-free hole-transport material for application in PSCs. These HTMs show excellent conductivity and hole-transport mobility. Consequently, the devices based on these two HTMs exhibit unusually high fill factors of 0.76 for HA1 and 0.78 for HA2, which are significantly higher than that obtained using spiro-OMeTAD (0.69). The cell based on HA1-HTM in its pristine form achieved a high power conversion efficiency of 11.98% under air conditions, which is comparable to the PCE of the cell employing the well-known doped spiro-MeOTAD (12.27%) under the same conditions. More importantly, their facile synthesis and purification without using column chromatography makes these new silver-based HTMs highly promising for future commercial applications of PSCs. These results provide a new way to develop more low-cost and high conductivity metal-complex based HTMs for efficient PSCs.

  • 169.
    Hua, Yong
    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.
    Zhang, J.
    Xu, Bo
    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.
    Liu, Peng
    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.
    Cheng, Ming
    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. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Johansson, E. M. J.
    Sveinbjörnsson, K.
    Aitola, K.
    Boschloo, G.
    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.
    Facile synthesis of fluorene-based hole transport materials for highly efficient perovskite solar cells and solid-state dye-sensitized solar cells2016In: Nano Energy, ISSN 2211-2855, Vol. 26, p. 108-113Article in journal (Refereed)
    Abstract [en]

    Two novel low-cost fluorene-based hole transport materials (HTMs) HT1 and HT2 as alternatives to the expensive HTM Spiro-OMeTAD have been designed and synthesized for the application in perovskite solar cells (PSCs) and solid-state dye-sensitized solar cell (ssDSCs). The two HTMs were prepared through a facile two-step reaction from cheap starting material and with a total yield higher than 90%. These HTMs exhibit good solubility and charge-transport ability. PSCs based on HT2 achieved power conversion efficiency (PCE) of 18.04% under air conditions, which is comparable to that of the cell employing the commonly used Spiro-OMeTAD (18.27%), while HT1-based cell showed a slightly worse performance with a PCE of 17.18%. For ssDSCs, the HT2-based device yielded a PCE of 6.35%, which is also comparable to that of a cell fabricated based on Spiro-OMeTAD (6.36%). We found that the larger dimensional structure and molecular weight of HT2 enable better photovoltaic performance than that of the smaller one HT1. These results show that easily synthesized fluorene-based HTMs have great potential to replace the expensive Spiro-OMeTAD for both PSCs and ssDSCs.

  • 170.
    Huang, Jing
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Yuan, Chunze
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Chen, Hong
    Sun, Junliang
    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.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Improved Performance of Colloidal CdSe Quantum Dot-Sensitized Solar Cells by Hybrid Passivation2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 21, p. 18808-18815Article in journal (Refereed)
    Abstract [en]

    A hybrid passivation strategy is employed to modify the surface of colloidal CdSe quantum dots (QDs) for quantum dot-sensitized solar cells (QDSCs), by using mercaptopropionic acid (MPA) and iodide anions through a ligand exchange reaction in solution. This is found to be an effective way to improve the performance of QDSCs based on colloidal QDs. The results show that MPA can increase the coverage of the QDs on TiO2 electrodes and facilitate the hole extraction from the photoxidized QDs, and simultaneously, that the iodide anions can remedy the surface defects of the CdSe QDs and thus reduce the recombination loss in the device. This hybrid passivation treatment leads to a significant enhancement of the power conversion efficiency of the QDSCs by 41%. Furthermore, an optimal ratio of iodide ions to MPA was determined for favorable hybrid passivation; results show that excessive iodine anions are detrimental to the loading of the QDs. This study demonstrates that the improvement in QDSC performance can be realized by using a combination of different functional ligands to passivate the QDs, and that ligand exchange in solution effective approach to introduce can be an different ligands.

  • 171. Huang, P.
    et al.
    Magnuson, A.
    Lomoth, R.
    Abrahamsson, M.
    Tamm, M.
    Sun, Licheng
    van Rotterdam, B.
    Park, J.
    Hammarstrom, L.
    Akermark, B.
    Styring, S.
    Photo-induced oxidation of a dinuclear Mn-2(II,II) complex to the Mn-2(III,IV) state by inter- and intramolecular electron transfer to Ru-III tris-bipyridine2002In: Journal of Inorganic Biochemistry, ISSN 0162-0134, E-ISSN 1873-3344, Vol. 91, no 1, p. 159-172Article in journal (Refereed)
    Abstract [en]

    To model the structural and functional parts of the water oxidizing complex in Photosystem 11, a dimeric manganese(II,11) complex (1) was linked to a ruthenium(II)tris-bipyridine (Ru-II(bpy)3) complex via a substituted L-tyrosine, to form the trinuclear complex 2 [J. Inorg. Biochem. 78 (2000) 15]. Flash photolysis of 1 and Ru-II(bpy), in aqueous solution, in the presence of an electron acceptor, resulted in the stepwise extraction of three electrons by Ru-III(bpy), from the Mn-2(II,II) dimer, which then attained the Mn-2(III,IV) oxidation state. In a similar experiment with compound 2, the dinuclear Mn complex reduced the photo-oxidized Ru moiety via intramolecular electron transfer on each photochemical event. From EPR it was seen that 2 also reached the Mn-2(III,IV) state. Our data indicate that oxidation from the Mn-2(II,II) state proceeds stepwise via intermediate formation of Mn-2(II,III) and Mn-2(III,III). In the presence of water, cyclic voltammetry showed an additional anodic peak beyond Mn-2(II,III/III,III) oxidation which was significantly lower than in neat acetonitrile. Assuming that this peak is due to oxidation to Mn-2(III,IV), this suggests that water is essential for the formation of the Mn-2(III,IV) oxidation state. Compound 2 is a structural mimic of the water oxidizing complex, in that it links a Mn complex via a tyrosine to a highly oxidizing photosensitizer. Complex 2 also mimics mechanistic aspects of Photosystem 11, in that the electron transfer to the photosensitizer is fast and results in several electron extractions from the Mn moiety.

  • 172. Jiang, J.
    et al.
    Wang, M.
    Yan, W.
    Liu, X.
    Liu, J.
    Yang, J.
    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.
    Highly active and durable electrocatalytic water oxidation by a NiB0.45/NiOx core-shell heterostructured nanoparticulate film2017In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 38, p. 175-184Article in journal (Refereed)
    Abstract [en]

    On the way to energy-efficient and cost-effective hydrogen production by electrochemical or photoelectrochemical water splitting, it is of primary importance to develop highly active and durable water oxidation electrocatalysts based on earth-abundant elements. Here we report a highly active, robust, cheap, and facilely fabricated O2-evolving catalyst on a Cu foil, NiB0.45-250/Cu, which forms a NiB0.45/NiOx core-shell heterostructured nanoparticulate film during anodic electrolysis. The performance of NiB0.45-250/Cu, to produce 10 mA cm−2 at 296 mV overpotential in 1 M KOH over 60 h, is at par with the best efficiency of earth-abundant electrocatalysts reported to date and surpasses that of IrO2-loaded copper electrode under identical conditions. Experimental evidence and theoretical calculations reveal the correlations of B/Ni atomic ratio and annealing temperature with the morphology, surface microtexture, electrochemical active surface area, and electrical conductivity of NiBx films. Optimal combination of these factors can evidently enhance the catalytic activity of nickel boride electrocatalysts.

  • 173. Jiang, Shi
    et al.
    Liu, Jianhui
    Shi, Yu
    Wang, Zhen
    Akermark, Bjorn
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fe-S complexes containing five-membered heterocycles: novel models for the active site of hydrogenases with unusual low reduction potential2007In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 8, p. 896-902Article in journal (Refereed)
    Abstract [en]

    Three biomimetic 2Fe2S complexes [{(mu-SCH2)(2)NCH2(2-C4H3O)}](Fe-2(CO)(6)) (6a), [{(mu-SCH2)(2) NCH2(2-C4H3S)}](Fe-2(CO)(6)) (6b) and [{(mu-SCH2)(2)NCH2(5-Br-2-C4H2S)}Fe-2(CO)(6)] (6c) were prepared as models for the active site of Fe-only hydrogenase by the convergent process from [(mu-S-2)Fe-2(CO)(6)] and N,N-bis(hydromethyl)-2-furan and thiophene. The structures of these complexes were identified spectroscopically and crystallographically. The electrochemical behavior of the complexes 6a and 6c was unique as they showed catalytic proton reduction with a low reduction potential at -1.13 and -1.09 V vs Fc/Fc(+), respectively, in the presence of HClO4.

  • 174. Jiang, Shi
    et al.
    Liu, Jianhui
    Shi, Yu
    Wang, Zhen
    Åkermark, Björn
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Preparation, characteristics and crystal structures of novel N-heterocyclic carbene substituted furan- and pyridine-containing azadithiolate Fe-S complexes2007In: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 26, no 7, p. 1499-1504Article in journal (Refereed)
    Abstract [en]

    Two novel N-heterocyclic carbene disubstituted furan- and pyridine-containing azadithiolate Fe-only hydrogenase models (2 and 4) have been synthesized, and characterized by IR and H-1 NMR spectra and X-ray single crystal diffraction. Cyclic voltammetry (CV) experiments indicate that they show more negative reductive potentials at -2.53 V and -2.49 V, respectively versus the ferrocene/ferrocenium couple (Fc/Fc(+)) and are easier to capture proton attributing to the strong electron-donating ligand NHC. After the protonation under F3CCO2H the reductive potentials of 2 and 4 have 1.02 V and 0.77 V shifts, indicating the formation of Fe-H-Fe bond. The results also are confirmed by the data changes in IR spectra and the negative H signals are detected by 1H NMR spectra at -27 ppm and -55 ppm.

  • 175. Jiang, X.
    et al.
    Yu, Z.
    Lai, J.
    Zhang, Y.
    Hu, M.
    Lei, N.
    Wang, D.
    Yang, X.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Interfacial Engineering of Perovskite Solar Cells by Employing a Hydrophobic Copper Phthalocyanine Derivative as Hole-Transporting Material with Improved Performance and Stability2017In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 8, p. 1838-1845Article in journal (Refereed)
    Abstract [en]

    In high-performance perovskite solar cells (PSCs), hole-transporting materials (HTMs) play an important role in extracting and transporting the photo-generated holes from the perovskite absorber to the cathode, thus reducing unwanted recombination losses and enhancing the photovoltaic performance. Herein, solution-processable tetra-4-(bis(4-tert-butylphenyl)amino)phenoxy-substituted copper phthalocyanine (CuPc-OTPAtBu) was synthesized and explored as a HTM in PSCs. The optical, electrochemical, and thermal properties were fully characterized for this organic metal complex. The photovoltaic performance of PSCs employing this CuPc derivative as a HTM was further investigated, in combination with a mixed-ion perovskite as a light absorber and a low-cost vacuum-free carbon as cathode. The optimized devices [doped with 6 % (w/w) tetrafluoro-tetracyano-quinodimethane (F4TCNQ)] showed a decent power conversion efficiency of 15.0 %, with an open-circuit voltage of 1.01 V, a short-circuit current density of 21.9 mA cm−2, and a fill factor of 0.68. Notably, the PSC devices studied also exhibited excellent long-term durability under ambient condition for 720 h, mainly owing to the introduction of the hydrophobic HTM interlayer, which prevents moisture penetration into the perovskite film. The present work emphasizes that solution-processable CuPc holds a great promise as a class of alternative HTMs that can be further explored for efficient and stable PSCs in the future.

  • 176.
    Jiang, Xiao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Karlsson, Karl Martin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Johansson, Erik M. J.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Quintana, Maria
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Karlsson, Martin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Boschloo, Gerrit
    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.
    Highly Efficient Solid-State Dye-Sensitized Solar Cells Based on Triphenylamine Dyes2011In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 21, no 15, p. 2944-2952Article in journal (Refereed)
    Abstract [en]

    Two triphenylamine-based metal-free organic sensitizers, D35 with a single anchor group and M14 with two anchor groups, have been applied in dye-sensitized solar cells (DSCs) with a solid hole transporting material or liquid iodide/triiodide based electrolyte. Using the molecular hole conductor 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)9,9'-spirobifluorene (spiro-OMeTAD), good overall conversion efficiencies of 4.5% for D35 and 4.4% for M14 were obtained under standard AM 1.5G illumination (100 mW cm(-2)). Although M14 has a higher molar extinction coefficient (by similar to 60%) and a slightly broader absorption spectrum compared to D35, the latter performs slightly better due to longer lifetime of electrons in the TiO(2), which can be attributed to differences in the molecular structure. In iodide/triiodide electrolyte-based DSCs, D35 outperforms M14 to a much greater extent, due to a very large increase in electron lifetime. This can be explained by both the greater blocking capability of the D35 monolayer and the smaller degree of interaction of triiodide (iodine) with D35 compared to M14. The present work gives some insight into how the molecular structure of sensitizer affects the performance in solid-state and iodide/triiodide-based DSCs.

  • 177.
    Jiang, Xiao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Marinado, Tannia
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Hagberg, Daniel P
    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, Inorganic Chemistry.
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Structural Modification of Organic Dyes for Efficient Coadsorbent-Free Dye-Sensitized Solar Cells2010In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 114, no 6, p. 2799-2805Article in journal (Refereed)
    Abstract [en]

    Three triphenylamine-based organic sensitizers with different electron-donating substituents (butoxyl chains or dimethylamine groups) were examined to investigate the effect of bulky alkoxy donor substituents on the photovoltaic performances of dye-sensitized solar cells (DSCs) in the presence and absence of the coadsorbent chenodeoxycholic acid (CDCA) in dye-bath solutions. The study showed that, using the D29 dye without bulky alkoxy substituents, the power conversion efficiency of DSC was significantly increased by about 84% in the presence of CDCA as compared to that in the absence of CDCA addition during the sensitization. However, the photovoltaic performance of D35-sensitized DSC having four bulky butoxyl substituents was not dependent on CDCA at all, probably due to the inherent structural nature of the D35 molecule. The DSC based on the D37 sensitizer with only two bulky butoxyl chains displayed an expected medium performance as compared to D29 and D35. The inclusion of bulky alkoxy electron-donating substituents in dye molecules for efficient DSCs suppressed the electron recombination and reduced the interactions between dye molecules. This emphasizes the importance of designing novel dyes including functional groups that incorporate the properties normally needed from an external coadsorbent. The development of a coadsorbent free system is in particular important for the future economization and simplification of the DSCs' assembly process.

  • 178. Jiang, Xiao
    et al.
    Yang, Xichuan
    Zhao, Changzhi
    Jin, Kun
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Electrogenerated chemiluminescence of a series of donor - Acceptor molecules and X-ray crystallographic evidence for the reaction mechanisms2007In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 111, no 26, p. 9595-9602Article in journal (Refereed)
    Abstract [en]

    Three series of donor-acceptor pi-conjugated (D-pi-A) molecules 1-3 have been synthesized with a 2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolinyl (Julolidine group), N,N-dimethylamino, or N,N-diphenylamino group as the donor moiety, a phenylvinyl or thienylvinyl unit as the bridge, and a bromide or aldehyde group as the acceptor moiety. The photophysical, electrochemical, and electrogenerated chemiluminescence (ECL) characters of these compounds have been studied in a 1:1 PhH/MeCN solution. Three different categories of ECL mechanisms for each of the three families of compounds are discussed, respectively. Compounds 1a-c produce typical and simple monomer ECL emission resulting from the annihilation of their radical cations and radical anions. The ECL emission of compounds 2a-c can be ascribed as an excimer emission. Compounds 3a-c exhibit an aggregate ECL emission. X-ray crystal structures of compounds 1b, 2a, and 3a provide further proof for the above-mentioned reaction mechanisms. All these compounds show stable ECL emission via the singlet excited state without the addition of any co-reactant or additional compound.

  • 179. Jiang, Xiao
    et al.
    Yang, Xichuan
    Zhao, Changzhi
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Electrogenerated chemiluminescence, of benzo 15-crown-5 derivatives2009In: Journal of Physical Organic Chemistry, ISSN 0894-3230, E-ISSN 1099-1395, Vol. 22, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Novel electrogenerated chemiluminescence (ECL) reagents C1, C2, and C3 with high fluorescence quantum yields bearing 15-crown-5 moiety have been synthesized and characterized. The photophysical, electrochemical, and ECL characters of these compounds have been studied in a 1:1 (v/v) PhH/MeCN mixed solvent. The ECL intensity is enhanced distinctly with the increase in the fluorescence quantum yield. Their ECL behaviors have been studied using annihilation and co-reactant methods (tri-n-propylamine (TPrA) was used as a co-reactant), respectively. The stable ECL emissions of compounds C1-C3 can be ascribed to the typical and simple monomer ECL emission via S-route.

  • 180.
    Jiang, Xiaoqing
    et al.
    Dalian Univ Technol, 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..
    Wang, Dongping
    Dalian Univ Technol, 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.;Shenyang Univ Chem Technol, Coll Chem Engn, Shenyang 110142, Liaoning, Peoples R China..
    Yu, Ze
    Dalian Univ Technol, 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..
    Ma, Wanying
    Shenyang Univ Chem Technol, Coll Chem Engn, Shenyang 110142, Liaoning, Peoples R China..
    Li, Hai-Bei
    Shandong Univ, Sch Ocean, Weihai 264209, Peoples R China..
    Yang, Xichuan
    Dalian Univ Technol, 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..
    Liu, Feng
    Shanghai Jiao Tong Univ, Dept Phys, Shanghai 200240, Peoples R China..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Molecular Engineering of Copper Phthalocyanines: A Strategy in Developing Dopant-Free Hole-Transporting Materials for Efficient and Ambient-Stable Perovskite Solar Cells2019In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 9, no 4, article id 1803287Article in journal (Refereed)
    Abstract [en]

    Copper (II) phthalocyanines (CuPcs) have attracted growing interest as promising hole-transporting materials (HTMs) in perovskite solar cells (PSCs) due to their low-cost and excellent stability. However, the most efficient PSCs using CuPc-based HTMs reported thus far still rely on hygroscopic p-type dopants, which notoriously deteriorate device stability. Herein, two new CuPc derivatives are designed, namely CuPc-Bu and CuPc-OBu, by molecular engineering of the non-peripheral substituents of the Pc rings, and applied as dopant-free HTMs in PSCs. Remarkably, a small structural change from butyl groups to butoxy groups in the substituents of the Pc rings significantly influences the molecular ordering and effectively improves the hole mobility and solar cell performance. As a consequence, PSCs based on dopant-free CuPc-OBu as HTMs deliver an impressive power conversion efficiency (PCE) of up to 17.6% under one sun illumination, which is considerably higher than that of devices with CuPc-Bu (14.3%). Moreover, PSCs containing dopant-free CuPc-OBu HTMs show a markedly improved ambient stability when stored without encapsulation under ambient conditions with a relative humidity of 85% compared to devices containing doped Spiro-OMeTAD. This work thus provides a fundamental strategy for the future design of cost-effective and stable HTMs for PSCs and other optoelectronic devices.

  • 181. Jiang, Xiaoqing
    et al.
    Yu, Ze
    Lai, Jianbo
    Zhang, Yuchen
    Lei, Ning
    Wang, Dongping
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Efficient perovskite solar cells employing a solution-processable copper phthalocyanine as a hole-transporting material2017In: Science China Chemistry, ISSN 1674-7291, Vol. 60, no 3, p. 423-430Article in journal (Refereed)
    Abstract [en]

    The development of alternative low-cost and high-performing hole-transporting materials (HTMs) is of great significance for the potential large-scale application of perovskite solar cells (PSCs) in the future. Here, a facilely synthesized solution-processable copper tetra-(2,4-dimethyl-3-pentoxy) phthalocyanine (CuPc-DMP) via only two simple steps, has been incorporated as a hole-transporting material (HTM) in mesoscopic perovskite solar cells (PSCs). The optimized devices based on such a HTM afford a very competitive power conversion efficiency (PCE) of up to 17.1% measured at 100 mW cm(-2) AM 1.5G irradiation, which is on par with that of the well-known 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) (16.7%) under equivalent conditions. This is, to the best of our knowledge, the highest value reported so far for metal organic complex-based HTMs in PSCs. The advantages of this HTM observed, such as facile synthetic procedure, superior hole transport characteristic, high photovoltaic performance together with the feasibility of tailoring the molecular structure would make solution-processable copper phthalocyanines as a class of promising HTM that can be further explored in PSCs. The present finding highlights the potential application of solution processed metal organic complexes as HTMs for cost-effective and high-performing PSCs.

  • 182. Jiang, Xiaoqing
    et al.
    Yu, Ze
    Li, Hai-Bei
    Zhao, Yawei
    Qu, Jishuang
    Lai, Jianbo
    Ma, Wanying
    Wang, Dongping
    Yang, Xichuan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    A solution-processable copper(II) phthalocyanine derivative as a dopant-free hole-transporting material for efficient and stable carbon counter electrode-based perovskite solar cells2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 34, p. 17862-17866Article in journal (Refereed)
    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.

  • 183. Jiang, Xiaoqing
    et al.
    Yu, Ze
    Zhang, Yuchen
    Lai, Jianbo
    Li, Jiajia
    Gurzadyan, Gagik G.
    Yang, Xichuan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    High-Performance Regular Perovskite Solar Cells Employing Low-Cost Poly(ethylenedioxythiophene) as a Hole-Transporting Material2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 42564Article in journal (Refereed)
    Abstract [en]

    Herein, we successfully applied a facile in-situ solid-state synthesis of conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) as a HTM, directly on top of the perovskite layer, in conventional mesoscopic perovskite solar cells (PSCs) (n-i-p structure). The fabrication of the PEDOT film only involved a very simple in-situ solid-state polymerisation step from a monomer 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) made from a commercially available and cheap starting material. The ultraviolet photoelectron spectroscopy (UPS) demonstrated that the as-prepared PEDOT film possesses the highest occupied molecular orbital (HOMO) energy level of -5.5 eV, which facilitates an effective hole extraction from the perovskite absorber as confirmed by the photoluminescence measurements. Optimised PSC devices employing this polymeric HTM in combination with a low-cost vacuum-free carbon cathode (replacing the gold), show an excellent power conversion efficiency (PCE) of 17.0% measured at 100 mW cm(-2) illumination (AM 1.5G), with an open-circuit voltage (V-oc) of 1.05 V, a short-circuit current density (J(sc)) of 23.5 mA/cm(2) and a fill factor (FF) of 0.69, respectively. The present finding highlights the potential application of PEDOT made from solid-state polymerisation as a HTM for cost-effective and highly efficient PSCs.

  • 184. Jiang, Yi
    et al.
    Li, Fei
    Huang, Fang
    Zhang, Biaobiao
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chemical and photocatalytic water oxidation by mononuclear Ru catalysts2013In: Cuihuà xuébào, ISSN 0253-9837, E-ISSN 1872-2067, Vol. 34, no 8, p. 1489-1495Article in journal (Refereed)
    Abstract [en]

    Four mononuclear Ru complexes with different substituents on the para position of the pyridine ligand of Ru(bda)(pic)(2) (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; pic = picoline) were synthesized and characterized by H-1 nuclear magnetic resonance or X-ray crystallography. The electrochemical properties of this series of compounds in acidic and neutral conditions were studied by cyclic voltammetry. Their catalytic activity towards water oxidation was investigated using a chemical oxidant ([Ce(NH4)(2)(NO3)(6)] (Ce-IV) in acidic solution, or driven by visible light in a three-component system containing a photosensitizer ([Ru(bpy)(3)](2+)) and an electron acceptor (S2O82-). For the chemical water oxidation, complex 1 was found to be the most effective, exhibiting a turnover number (TON) of up to 4000. The pyridine substituent at the 4-position in 1 may be protonated giving an intensive electron-withdrawing effect. Complex 2 bears the most electron-withdrawing trifluoromethyl group under neutral conditions and showed the highest photocatalytic activity with a TON of 270 over 2 h. It was concluded that the more electron-withdrawing substituents led to higher activity towards oxygen evolution for this type of Ru catalysts in the oxidation of water.

  • 185. Jiang, Yi
    et al.
    Li, Fei
    Zhang, Biaobiao
    Li, Xiaona
    Wang, Xiaohong
    Huang, Fang
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Promoting the Activity of Catalysts for the Oxidation of Water with Bridged Dinuclear Ruthenium Complexes2013In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 12, p. 3398-3401Article in journal (Refereed)
    Abstract [en]

    Solar fuels: Dinuclear ruthenium catalysts prepared from two covalently bridged monomeric catalytic units show outstanding activities towards the oxidation of water with high turnover numbers up to 43 000 and turnover frequencies up to 40 s-1 (see picture). Direct comparison of the performance parameters indicates that the dimers are significantly more active as catalysts than the monomers.

  • 186. Johansson, Erik M. J.
    et al.
    Yang, Lei
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lohse, Peter W.
    Boschloo, Gerrit
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hagfeldt, Anders
    Combining a Small Hole-Conductor Molecule for Efficient Dye Regeneration and a Hole-Conducting Polymer in a Solid-State Dye-Sensitized Solar Cell2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 34, p. 18070-18078Article in journal (Refereed)
    Abstract [en]

    In dye-sensitized solar cells (DSC) an efficient transfer of dioles from the oxidized dye to the contact is necessary, which in solid-state DSC is performed by hole-conductor molecules. In this report we use photoinduced absorption and transient absorption spectroscopy to show that a small hole-conducting molecule, tris(p-anisyl)amine, regenerates dye molecules in the pores of the dye-sensitized TiO2 nanoparticle electrode efficiently even for thick (>5 mu m) electrodes. For similar thicknesses we observe incomplete regeneration using a larger polymer hole-conductor. However, the performance of the solar cells with the small hole-conductor molecules is poor due to that inefficient hole conduction in these small molecules may limit the collection of the charges at the contacts. Polymer hole-conductors, which may have a good hole conductivity, also have a high molecular weight, which makes these polymers difficult to infiltrate into the smallest pores in the electrode. We show that a conducting polymer, P3HT, may be added to the small molecule hole-conductor, to enable better transport of the charges to the contact and to reduce recombination and therefore increase the photocurrent. This new device construction with a small molecule efficiently regenerating the dye molecules, and a polymer conducting the holes to the contact is therefore a promising pathway for solid-state dye-sensitized solar cells.

  • 187.
    Karlsson, K. Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Hagberg, Daniel P.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Marinado, Tannia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Design and synthesis of novel organic chromophores for dye sensitized solar cells - 22008In: ACS National Meeting Book of Abstracts, 2008, p. ORGN 493-Conference paper (Refereed)
    Abstract [en]

    One of the main issues of today is the energy problem where the use of fossil fuels has lead to environmental changes. The development of environmentally friendly alternatives is therefore of great importance. The sun is the perfect energy source since it supplies the earth with much more energy than we currently need. The development of dye sensitized solar cells (DSSC's) is one possible low cost alternative to harvest the solar energy. Here we present a series of different organic dyes for DSSC's in our search for better understanding of the dye's influence on the solar cell's performance. The aim of this work has been to alter the linker between the donor and acceptor parts in the chromophore in order to investigate how this will influence light absorption and efficiency of the solar cell.

  • 188.
    Karlsson, Karl Martin
    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.
    Jiang, Xiao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Eriksson, Susanna K
    Gabrielsson, Erik
    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.
    Rensmo, Håkan
    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.
    Phenoxazine Dyes for Dye-Sensitized Solar Cells: Relationship Between Molecular Structure and Electron Lifetime.2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 23, p. 6415-6424Article in journal (Refereed)
    Abstract [en]

    A series of metal-free organic dyes with a core phenoxazine chromophore have been synthesized and tested as sensitizers in dye-sensitized solar cells. Overall conversion efficiencies of 6.03-7.40 % were reached under standard AM 1.5G illumination at a light intensity of 100 mW cm(-2) . A clear trend in electron lifetime could be seen; a dye with a furan-conjugated linker showed a shorter lifetime relative to dyes with the acceptor group directly attached to the phenoxazine. The addition of an extra donor unit, which bore insulating alkoxyl chains, in the 7-position of the phenoxazine could increase the lifetime even further and, together with additives in the electrolyte to raise the conduction band, an open circuit voltage of 800 mV could be achieved. From photoelectron spectroscopy and X-ray absorption spectroscopy of the dyes adsorbed on TiO(2) particles, it can be concluded that the excitation is mainly of cyano character (i.e., on average, the dye molecules are standing on, and pointing out, from the surface of TiO(2) particles).

  • 189.
    Karlsson, Karl Martin
    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.
    Jiang, Xiao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kaufmann, Susanna
    Gabrielsson, Erik
    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.
    Johansson, Erik Martin Jesper
    Marinado, Tannia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Rensmo, Håkan
    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.
    Triphenylamine Based Organic Chromophores Containing Two Anchoring Groups for Dye Sensitized Solar CellsManuscript (preprint) (Other academic)
  • 190. Karlsson, Martin
    et al.
    Yang, Lei
    Karlsson, Marlin K.
    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.
    Boschloo, Gerrit
    Hagfeldt, Anders
    Phenoxazine dyes in solid-state dye-sensitized solar cells2012In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 239, p. 55-59Article in journal (Refereed)
    Abstract [en]

    Several structural modifications have been made to a sensitizer dye based on the phenoxazine core. which was tested in a solid-state dye-sensitized solar cell configuration based on the hole transporting material 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9'-spirofluorene. Light-to-power conversion efficiencies between 2.5% and 4.1% are reported herein. The difference in device performance is significantly related to the variations of dye molecular structure, with dye molecules having surface protecting alkoxy-groups yielding better solar cell devices. The phenoxazine dyes were characterized by their light harvesting capabilities and electronic properties such as electron recombination lifetime and chemical dipole moment.

  • 191. Kong, Zhixia
    et al.
    Zhou, Huizhi
    Cui, Jingnan
    Ma, Tingli
    Yang, Xichuan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    A new class of organic dyes based on acenaphthopyrazine for dye-sensitized solar cells2010In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 213, no 2-3, p. 152-157Article in journal (Refereed)
    Abstract [en]

    A new class of organic dyes based on acenaphthopyrazine derivatives, containing pyrazine group as the electron acceptor and o-dicarboxyl acids as the anchoring groups were designed and synthesized for application in dye-sensitized solar cells (DSCs). These dyes have short synthesis routes and are easily adsorbed on the surface of TiO2. Under illumination of simulated AM1.5 solar light (100 mW cm(-2)), a total solar energy conversion efficiency (eta) of 4.04% was obtained for the 3-(diphenylamino)acenaphtho[1,2-b] pyrazine-8,9-dicarboxylic acid (AP-1) in the preliminary tests, in comparison with the conventional N719 dye (eta=7.05%) under the same conditions.

  • 192. Kuang, Daibin
    et al.
    Comte, Pascal
    Zakeeruddin, Shaik M.
    Hagberg, Daniel P.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Karlsson, Karl Martin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Nazeeruddin, Md K.
    Grätzel, Michael
    Stable dye-sensitized solar cells based on organic chromophores and ionic liquid electrolyte2011In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 85, no 6, p. 1189-1194Article in journal (Refereed)
    Abstract [en]

    A series of polyene-diphenylaniline based organic dyes (coded as D5, D7, D9 and D11) have been reported for the application in ionic liquid electrolyte based dye-sensitized solar cells. The effects of substitution of organic dyes on the photovoltaic performance have been investigated, which show addition of methoxy groups on the triphenylamine donor group increases short-circuit current, open-circuit voltage and photovoltaic performance. A power conversion efficiency of 6.5% under AM 1.5 sunlight at 100 mW/cm(2) has been obtained with D11 dye in combination with a binary ionic liquid electrolyte, which when subjected to accelerated testing under one sun light soaking at 60 degrees C, the efficiency remained 90% of initial efficiency.

  • 193. Kumagai, Hiromu
    et al.
    Hammarstrom, Leif
    Whang, Dong Ryeol
    Shinohara, Yuki
    Martinez, Jose
    Karlsson, Joshua
    Summers, Peter
    Windle, Christopher D.
    Kodera, Masanori
    Cogdell, Richard
    Tolod, Kristine Rodulfo
    Apaydin, Dogukan Hazar
    Fujita, Etsuko
    Kibler, Alexander
    Fan, Fengtao
    Gibson, Elizabeth A.
    Usami, Hisanao
    Iwase, Akihide
    Inoue, Haruo
    Kudo, Akihiko
    Gust, Devens
    Domen, Kazunari
    Cassiola, Flavia
    Takagi, Katsuhiko
    Kang, Sang Ook
    Yamakata, Akira
    Li, Can
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Park, Hyunwoong
    Kang, Young Soo
    Li, Rengui
    Di Fonzo, Fabio
    Setoyama, Tohru
    Ishitani, Osamu
    Inorganic assembly catalysts for artificial photosynthesis: general discussion2017In: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 198, p. 481-507Article in journal (Refereed)
  • 194. Leandri, V.
    et al.
    Ellis, H.
    Gabrielsson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. State Key Laboratory of Fine Chemicals, DUT-KTH Joint Research Center on Molecular Devices, Dalian University of Technology (DUT), China .
    Boschloo, G.
    Hagfeldt, A.
    An organic hydrophilic dye for water-based dye-sensitized solar cells2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 37, p. 19964-19971Article in journal (Refereed)
    Abstract [en]

    In this study we report the first organic hydrophilic dye employed for 100% water-based electrolyte DSSCs. We show that the replacement of alkyl by glycolic chains in the dye structure is able to provide excellent wettability, resulting in an efficient system with remarkably reduced desorption problems that allowed us to perform tests over a wide pH range. By changing the electrolyte composition, employing chenodeoxycholic acid as a co-adsorbent and using PEDOT counter-electrodes, 3% power conversion efficiency under 1-sun illumination was obtained. We show that chenodeoxycholic acid does not significantly increase the wettability, and we provide new insights into the higher performance resulting from its co-adsorption.

  • 195.
    Leandri, Valentina
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Daniel, Quentin
    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.
    Chen, Hong
    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.
    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.
    Gardner, James M.
    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.
    Electronic and Structural Effects of Inner Sphere Coordination of Chloride to a Homoleptic Copper(II) Diimine Complex2018In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 8, p. 4556-4562Article in journal (Refereed)
    Abstract [en]

    The reaction of CuCl2 with 2,9-dimethyl-1,10-phenanthroline (dmp) does not lead to the formation of [Cu(dmp)(2)](Cl)(2) but instead to [Cu(dmp)(2)Cl]Cl, a 5-coordinated complex, in which one chloride is directly coordinated to the metal center. Attempts at removing the coordinated chloride by changing the counterion by metathesis were unsuccessful and resulted only in the exchange of the noncoordinated chloride, as confirmed from a crystal structure analysis. Complex [Cu-(dmp)(2)Cl]PF6 exhibits a reversible cyclic voltammogram characterized by a significant peak splitting between the reductive and oxidative waves (0.85 and 0.60 V vs NHE, respectively), with a half-wave potential E-1/2 = 0.73 V vs NHE. When reduced electrochemically, the complex does not convert into [Cu(dmp)(2)](+), as one may expect. Instead, [Cu(dmp)(2)](+) is isolated as a product when the reduction of [Cu(dmp)(2)Cl]PF6 is performed with L-ascorbic acid, as confirmed by electrochemistry, NMR spectroscopy, and diffractometry. [Cu(dmp)(2)](2+) complexes can be synthesized starting from Cu(II) salts with weakly and noncoordinating counterions, such as perchlorate. Growth of [Cu(dmp)(2)](ClO4)(2) crystals in acetonitrile results in a 5-coordinated complex, [Cu(dmp)(2)(CH3CN)](ClO4)(2), in which a solvent molecule is coordinated to the metal center. However, solvent coordination is associated with a dynamic decoordination-coordination behavior upon reduction and oxidation. Hence, the cyclic voltammogram of [Cu(dmp)(2)(CH3CN)](2+) is identical to the one of [Cu(dmp)(2)](+), if the measurements are performed in acetonitrile. The current results show that halide ions in precursors to Cu(II) metal-organic coordination compound synthesis, and most likely also other multivalent coordination centers, are not readily exchanged when exposed to presumed strongly binding and chelating ligand, and thus special care needs to be taken with respect to product characterization.

  • 196.
    Leandri, Valentina
    et al.
    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
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Franchi, Daniele
    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.
    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.
    Benesperi, Iacopo
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Freitag, Marina
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Sun, Licheng
    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. DUT, DUT KTH Joint Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    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.
    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.
    Exploring the Optical and Electrochemical Properties of Homoleptic versus Heteroleptic Diimine Copper(I) Complexes2019In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 18, p. 12167-12177Article in journal (Refereed)
    Abstract [en]

    Due to ligand scrambling, the synthesis and investigation of the properties of heteroleptic Cu(I) complexes can be a challenging task. In this work, we have studied the optical and electrochemical properties of a series of homoleptic complexes, such as [Cu(dbda)(2)](+), [Cu(dmp)(2)](+), [Cu(Br-dmp)(2)](+), [Cu(bcp)(2)](+), [Cu(dsbtmp)(2)](+), [Cu(biq)(2)](+), and [Cu(dap)(2)](+) in solution, and those of their heteroleptics [Cu(dbda)(dmp)](+), [Cu(dbda)(Br-dmp)](+), [Cu(dbda)(bcp)](+), [Cu(dbda)(dsbtmp))(+), [Cu(dbda)(biq)](+), [Cu(dbda)(dap)](+) adsorbed on the surface of anatase TiO2 (dbda = 6,6'-dimethyl-2,2'-bipyridine-4,4'-dibenzoic acid; dmp = 2,9-dimethyl-1,10-phenanthroline; Br-dmp = 5-bromo 2,9-dimethyl-1,10-phenanthroline; bcp = bathocuproine or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; dsbtmp = 2,9-di(sec-butyl)-3,4,7,8-tetramethyl-1,10-phenanthroline; biq = 2,2'-biquinoline; dap = 2,9-dianisyl-1,10-phenanthroline). We show that the maximum absorption wavelengths of the heteroleptic complexes on TiO2 can be reasonably predicted from those of the homoleptic complexes in solution through a simple linear relation, whereas the prediction of their redox properties is less trivial. In the latter case, two different linear patterns emerge: one including the ligands bcp, biq, and dap and another one including the ligands dmp, Br-dmp, and dsbtmp. We offer an interpretation of the data based on the chemical structure of the ligands. On one hand, ligands bcp, biq, and dap possess a more extended pi-conjugated system, which gives a more prominent contribution to the overall redox properties of the ligand dbda. On the other hand, the ligands dmp, Br-dmp, and dsbtmp are all phenanthroline-based containing alkyl substituents and contribute less than dbda to the overall redox properties.

  • 197. Lee, H.
    et al.
    Wu, X.
    Yang, X.
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Ligand-Controlled Electrodeposition of Highly Intrinsically Active and Optically Transparent NiFeOxHy Film as a Water Oxidation Electrocatalyst2017In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 23, p. 4690-4694Article in journal (Refereed)
    Abstract [en]

    A highly intrinsically active and optically transparent NiFeOxHy water oxidation catalyst was prepared by electrodeposition of [Ni(C12-tpen)](ClO4)2 complex (Ni−C12). This NiFeOxHy film has a current density of 10 mA cm−2 with an overpotential (η) of only 298 mV at nanomolar concentration and the current density of 10 mA cm−2 remains constant over 22 h in 1 m KOH. The extremely high turnover frequency of 0.51 s−1 was obtained with η of 300 mV. More importantly, such outstanding activity and transparency (optical loss <0.5 %) of the NiFeOxHy film are attributed to a ligand effect of the dodecyl substituent in Ni−C12, which enables its future application in solar water splitting.

  • 198.
    Lee, Husileng
    et al.
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Wu, Xiujuan
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Ye, Qilun
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Wu, Xingqiang
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Wang, Xiaoxiao
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Zhao, Yimeng
    DUT, State Key Lab Fine Chem, DUT KTH Joint Educ & Res Ctr Mol Devices, Dalian 116024, Peoples R China..
    Sun, Licheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Hierarchical CoS2/Ni3S2/CoNiOx nanorods with favorable stability at 1 A cm(-2) for electrocatalytic water oxidation2019In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 11, p. 1564-1567Article in journal (Refereed)
    Abstract [en]

    Herein, we have reported an easily synthesized CoS2/Ni3S2/CoNiOx water oxidation catalyst with excellent catalytic activity and superior durability. The as-prepared catalyst required overpotential (eta) as low as 256 mV to exhibit a current density of 10 mA cm(-2) in 1.0 M KOH. Remarkably, it sustained a current density of 1 A cm(-2) for one week in 30% KOH solution with only 25 mV increment of eta. Thus, it is a hopeful candidate as a highly-effective water oxidation electrode in practical applications.

  • 199. Lele, Duan
    et al.
    Mei, Wang
    Ping, Li
    Yong, Na
    Ning, Wang
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Carbene-pyridine chelating 2Fe2S hydrogenase model complexes as highly active catalysts for the electrochemical reduction of protons from weak acid (HOAc)2007In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 13, p. 1277-1283Article in journal (Refereed)
    Abstract [en]

    Two asymmetrically disubstituted diiron complexes (mu-pdt)[Fe(CO)(3)][Fe(CO)(eta(2)-L)] (L = 1-methyl-3-(2-pyridyl)imidazol-2-ylidene (NHCMePy), 2; 1,3-bis(2-picolyl) imidazol-2-ylidene (NHCdiPic), 4) and a mono-substituted diiron complex (mu-pdt)[Fe(CO)(3)][Fe(CO)(2)(NHCdiPic)] (3) were prepared as biomimetic models of the Fe-only hydrogenase active site. X-Ray studies show that the NHCMePy and NHCdiPic ligands in 2 and 4 each coordinate to the single iron atom as NHC-Py chelating ligands in two basal positions and the NHCdiPic ligand of complex 3 lies in an apical position as a monodentate ligand. The large ranges of the highest and the lowest nu(CO) frequencies of 2 and 4 reflect that the relatively uneven electron density on the two iron atoms of the 2Fe2S model complexes 2 and 4 is as that observed for mono-substituted diiron complexes of good donor ligands. The cyclic voltammograms and the electrochemical proton reduction by 2 and 3 were studied in the presence of HOAc to evaluate the effect of asymmetrical substitution of strong donor ligands on the redox properties of the iron atoms and on the electrocatalytic activity for proton reduction.

  • 200. Li, Chaoyan
    et al.
    Yang, Xichuan
    Chen, Ruikui
    Pan, Jingxi
    Tian, Haining
    Zhu, Hongjun
    Wang, Xiuna
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Anthraquinone dyes as photosensitizers for dye-sensitized solar cells2007In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 91, no 19, p. 1863-1871Article in journal (Refereed)
    Abstract [en]

    Three anthraquitione dyes with carboxylic acid as anchoring group are designed and synthesized as sensitizers for dye-sensitized solar cells (DSSCs). Preliminary photophysical and photoelectrochemical measurements show that these anthraquinone dyes have very low performance on DSSC applications, although they have broad and intense absorption spectra in the visible region (up to 800nm). Transient absorption kinetics, fluorescence lifetime measurements and density functional theory (DFT) calculations are conducted to investigate the cause of such low DSSC performance for these dyes. The results show that the strong electron -withdrawing character of the two carbonyl groups on anthraquinone framework may lie behind the low performance by suppressing the efficient electron injection from the dye to the conduction band of TiO2.

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