Xiao Zewen, Meng Weiwei, Wang Jianbo, Yan Yanfa
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.
ChemSusChem. 2016 Sep 22;9(18):2628-2633. doi: 10.1002/cssc.201600771. Epub 2016 Aug 4.
Bismuth- or antimony-based lead-free double perovskites represented by Cs AgBiBr have 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 Cs AgBiBr is narrow. Ag vacancies are a shallow accepters and can easily form, leading to intrinsic p-type conductivity. Bi vacancies and Ag antisites are deep acceptors and should be the dominant defects under the Br-rich growth conditions. Our results suggest that the growth of Cs AgBiBr under Br-poor/Bi-rich conditions is preferred for suppressing the formation of the deep defects, which is beneficial for maximizing the photovoltaic performance.
以CsAgBiBr为代表的铋基或锑基无铅双钙钛矿最近被认为是用于太阳能电池应用的新兴铅基钙钛矿的有前途的替代品。这些新型钙钛矿属于Fm3‾m空间群，由两种类型的八面体在岩盐面心立方结构中交替组成。我们通过密度泛函理论计算表明，纯CsAgBiBr的稳定化学势区域很窄。银空位是浅受主，很容易形成，导致本征p型导电性。铋空位和银反位是深受主，在富溴生长条件下应该是主要缺陷。我们的结果表明，在贫溴/富铋条件下生长CsAgBiBr有利于抑制深缺陷的形成，这有利于最大化光伏性能。
