title: Kesterite Cu2ZnSnS4 as a Low-Cost Inorganic Hole-Transporting Material for High-Efficiency Perovskite Solar Cells.
abstract: Kesterite-structured quaternary semiconductor Cu2ZnSnS4 (CZTS) has been commonly used as light absorber in thin film solar cells on the basis of its optimal bandgap of 1.5 eV, high absorption coefficient, and earth-abundant elemental constituents. Herein we applied CZTS nanoparticles as a novel inorganic hole transporting material (HTM) for organo-lead halide perovskite solar cells (PSCs) for the first time, achieving a power conversion efficiency (PCE) of 12.75%, which is the highest PCE for PSCs with Cu-based inorganic HTMs reported up to now, and quite comparable to that obtained for PSCs based on commonly used organic HTM such as 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeOTAD). The size of CZTS nanoparticles and its incorporation condition as HTM were optimized, and the effects of CZTS HTM on the optical absorption, crystallinity, morphology of the perovskite film and the interface between the perovskite layer and the Au electrode were investigated and compared with the case of spiro-MeOTAD HTM, revealing the role of CZTS in efficient hole transporting from the perovskite layer to the top Au electrode as confirmed by the prohibited charge recombination at the perovskite/Au electrode interface. On the basis of the effectiveness of CZTS as a low-cost HTM competitive to spiro-MeOTAD in PSCs, we demonstrate the new role of CZTS in photovoltaics as a hole conductor beyond the traditional light absorber.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China (USTC) , Hefei 230026, China.
authors.forename: Qiliang
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China (USTC) , Hefei 230026, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Xue
authors.affiliation: Key Laboratory of Novel Thin Film Solar Cells, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China (USTC) , Hefei 230026, China.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China (USTC) , Hefei 230026, China.
authors.forename: Weifeng
authors.initials: W
authors.lastname: Liu
authors.affiliation: Key Laboratory of Novel Thin Film Solar Cells, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Novel Thin Film Solar Cells, Hefei Institutes of Physical Science, Chinese Academy of Sciences , Hefei 230031, China.|Beijing Key Lab of Novel Thin Film Solar Cells, North China Electric Power University , Beijing 102206, China.
authors.forename: Songyuan
authors.initials: S
authors.lastname: Dai
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China (USTC) , Hefei 230026, China.
authors.forename: Changfei
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering, Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China (USTC) , Hefei 230026, China.
authors.forename: Shangfeng
authors.initials: S
authors.lastname: Yang
keywords: CZTS; hole-transport material; interface; light absorber; perovskite solar cells