The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Sekai Tombe - One of the best experts on this subject based on the ideXlab platform.
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optical and electronic properties of mixed Halide x i cl br methylammonium lead perovskite solar cells
Journal of Materials Chemistry C, 2017Co-Authors: Sekai Tombe, Getachew Adam, Herwig Heilbrunner, Dogukan Hazar Apaydin, Christoph Ulbricht, N S Sariciftci, C J Arendse, Emmanuel I Iwuoha, Markus C ScharberAbstract:We report on the fabrication and opto-electronic characterization of solution-processed planar heterojunction perovskite solar cells based on methylammonium (MA) lead Halide derivatives, MAPbI3−xYx (Y = Cl, Br, I). Dissolving equimolar amounts of lead iodide (PbI2) and methylammonium iodide (H3CNH3I) together with various amounts of additional methylammonium Halides, perovskite precursor solutions were obtained, which were used in the fabrication of three perovskite systems, MAPbI3, MAPbI3−xClx and MAPbI3−xBrx. The effect of the Halide ratio in the perovskite formulations processed via a one-step deposition technique on optoelectronic properties and on photovoltaic performance of the formed perovskites was investigated. The perovskite film morphology, temperature-dependent photoluminescence properties, hysteresis behaviour in current–voltage characteristics and the photovoltaic performance as a function of chemical composition were studied using microscopic, spectroscopic and photovoltaic characterization techniques. The power conversion efficiency was found to be dependent on MAPbI3−xYx (Y = Cl, Br, I) perovskite film morphology. By controlling perovskite precursor composition and stoichiometry, highest power conversion efficiencies of 9.2, 12.5 and 5.4% were obtained for MAPbI3, MAPbI3−xClx and MAPbI3−xBrx devices, respectively. In addition, the physical parameters of the mixed Halide perovskites such as the exciton binding energy, exciton–phonon interaction and bandgap were determined via temperature-dependent photoluminescence spectroscopy. Exciton binding and optical phonon energies of MAPbI3−xYx (Y = Cl, Br, I) were found to be in the ranges of 49–68 meV and 29–32 meV respectively. The solution-processed MA lead Halide derivatives form highly crystalline materials with chemical versatility allowing the tuning of their optical and electronic properties depending on the nature and the ratio of the Halides employed.
Markus C Scharber - One of the best experts on this subject based on the ideXlab platform.
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optical and electronic properties of mixed Halide x i cl br methylammonium lead perovskite solar cells
Journal of Materials Chemistry C, 2017Co-Authors: Sekai Tombe, Getachew Adam, Herwig Heilbrunner, Dogukan Hazar Apaydin, Christoph Ulbricht, N S Sariciftci, C J Arendse, Emmanuel I Iwuoha, Markus C ScharberAbstract:We report on the fabrication and opto-electronic characterization of solution-processed planar heterojunction perovskite solar cells based on methylammonium (MA) lead Halide derivatives, MAPbI3−xYx (Y = Cl, Br, I). Dissolving equimolar amounts of lead iodide (PbI2) and methylammonium iodide (H3CNH3I) together with various amounts of additional methylammonium Halides, perovskite precursor solutions were obtained, which were used in the fabrication of three perovskite systems, MAPbI3, MAPbI3−xClx and MAPbI3−xBrx. The effect of the Halide ratio in the perovskite formulations processed via a one-step deposition technique on optoelectronic properties and on photovoltaic performance of the formed perovskites was investigated. The perovskite film morphology, temperature-dependent photoluminescence properties, hysteresis behaviour in current–voltage characteristics and the photovoltaic performance as a function of chemical composition were studied using microscopic, spectroscopic and photovoltaic characterization techniques. The power conversion efficiency was found to be dependent on MAPbI3−xYx (Y = Cl, Br, I) perovskite film morphology. By controlling perovskite precursor composition and stoichiometry, highest power conversion efficiencies of 9.2, 12.5 and 5.4% were obtained for MAPbI3, MAPbI3−xClx and MAPbI3−xBrx devices, respectively. In addition, the physical parameters of the mixed Halide perovskites such as the exciton binding energy, exciton–phonon interaction and bandgap were determined via temperature-dependent photoluminescence spectroscopy. Exciton binding and optical phonon energies of MAPbI3−xYx (Y = Cl, Br, I) were found to be in the ranges of 49–68 meV and 29–32 meV respectively. The solution-processed MA lead Halide derivatives form highly crystalline materials with chemical versatility allowing the tuning of their optical and electronic properties depending on the nature and the ratio of the Halides employed.
Jae Kyu Song - One of the best experts on this subject based on the ideXlab platform.
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reversible Halide exchange reaction of organometal triHalide perovskite colloidal nanocrystals for full range band gap tuning
Nano Letters, 2015Co-Authors: Dong Myung Jang, Kidong Park, Jeunghee Park, Fazel Shojaei, Hong Seok Kang, Jae Kyu SongAbstract:In recent years, methylammonium lead Halide (MAPbX3, where X = Cl, Br, and I) perovskites have attracted tremendous interest caused by their outstanding photovoltaic performance. Mixed Halides have been frequently used as the active layer of solar cells, as a result of their superior physical properties as compared to those of traditionally used pure iodide. Herein, we report a remarkable finding of reversible Halide-exchange reactions of MAPbX3, which facilitates the synthesis of a series of mixed Halide perovskites. We synthesized MAPbBr3 plate-type nanocrystals (NCs) as a starting material by a novel solution reaction using octylamine as the capping ligand. The synthesis of MAPbBr3–xClx and MAPbBr3–xIx NCs was achieved by the Halide exchange reaction of MAPbBr3 with MACl and MAI, respectively, in an isopropyl alcohol solution, demonstrating full-range band gap tuning over a wide range (1.6–3 eV). Moreover, photodetectors were fabricated using these composition-tuned NCs; a strong correlation was observ...
Jeff Xin Wu - One of the best experts on this subject based on the ideXlab platform.
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mild conversion of alcohols to alkyl Halides using Halide based ionic liquids at room temperature
Organic Letters, 2001Co-Authors: Jeff Xin WuAbstract:Alcohols were efficiently converted to alkyl Halides using 1-n-butyl-3-methylylimidazolium Halides (ionic liquids) in the presence of Bronsted acids at room temperature. The alkyl Halide products were easily isolated from the reaction mixture via simple decantation or extraction, and the 1-n-butyl-3-methylimidazolium cation could be recycled for further uses.
Annemarie Pucci - One of the best experts on this subject based on the ideXlab platform.
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infrared spectroscopic study of vibrational modes in methylammonium lead Halide perovskites
Journal of Physical Chemistry Letters, 2015Co-Authors: Tobias Glaser, Michael Sendner, Christian Krekeler, Octavi E Semonin, Trevor D Hull, Omer Yaffe, Jonathan S Owen, Wolfgang Kowalsky, Christian Muller, Annemarie PucciAbstract:The organic cation and its interplay with the inorganic lattice underlie the exceptional optoelectronic properties of organo-metallic Halide perovskites. Herein we report high-quality infrared spectroscopic measurements of methylammonium lead Halide perovskite (CH3NH3Pb(I/Br/Cl)3) films and single crystals at room temperature, from which the dielectric function in the investigated spectral range is derived. Comparison with electronic structure calculations in vacuum of the free methylammonium cation allows for a detailed peak assignment. We analyze the shifts of the vibrational peak positions between the different Halides and infer the extent of interaction between organic moiety and the surrounding inorganic cage. The positions of the NH3+ stretching vibrations point to significant hydrogen bonding between the methylammonium and the Halides for all three perovskites.
