title: Thermodynamic Stability and Defect Chemistry of Bismuth-Based Lead-Free Double Perovskites.
abstract: Bismuth- or antimony-based lead-free double perovskites represented by Cs2AgBiBr6have recently been considered promising alternatives to the emerging lead-based perovskites for solar cell applications. These new perovskites belong to the Fm3‾ m space group and consist of two types of octahedra alternating in a rock-salt face-centered cubic structure. We show, by density functional theory calculations, that the stable chemical potential region for pure Cs2AgBiBr6is narrow. Ag vacancies are a shallow accepters and can easily form, leading to intrinsic p-type conductivity. Bi vacancies and AgBiantisites are deep acceptors and should be the dominant defects under the Br-rich growth conditions. Our results suggest that the growth of Cs2AgBiBr6under Br-poor/Bi-rich conditions is preferred for suppressing the formation of the deep defects, which is beneficial for maximizing the photovoltaic performance.
authors.affiliation: Department of Physics and Astronomy, Wright Center for Photovoltaic Innovation and Commercialization, The University of Toledo, Toledo, Ohio, 43606, USA. zewen.xiao@utoledo.edu.
authors.forename: Zewen
authors.initials: Z
authors.lastname: Xiao
authors.affiliation: Department of Physics and Astronomy, Wright Center for Photovoltaic Innovation and Commercialization, The University of Toledo, Toledo, Ohio, 43606, USA.|School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, Institute for Advanced Studies, Wuhan University, Wuhan, 430072, China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Meng
authors.affiliation: School of Physics and Technology, Center for Electron Microscopy, MOE Key Laboratory of Artificial Micro- and Nano-structures, Institute for Advanced Studies, Wuhan University, Wuhan, 430072, China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Physics and Astronomy, Wright Center for Photovoltaic Innovation and Commercialization, The University of Toledo, Toledo, Ohio, 43606, USA. yanfa.yan@utoledo.edu.
authors.forename: Yanfa
authors.initials: Y
authors.lastname: Yan
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D004355:Drug Stability; D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D010087:Oxides / Q000737:chemistry*; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D010087:Oxides; C059910:perovskite; D014025:Titanium; D001729:Bismuth
keywords: defect properties; double perovskite; lead-free; photovoltaic; stability