Xu Jian, Liu Jian-Bo, Liu Bai-Xin, Huang Bing
Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University , Beijing 100084, China.
Beijing Computational Science Research Center , Beijing 100094, China.
J Phys Chem Lett. 2017 Sep 21;8(18):4391-4396. doi: 10.1021/acs.jpclett.7b02008. Epub 2017 Sep 1.
Lead-free halide double perovskites (HDPs) are expected to be promising photovoltaic (PV) materials beyond organic-inorganic halide perovskite, which is hindered by its structural instability and toxicity. The defect- and stability-related properties of HDPs are critical for the use of HDPs as important PV absorbers, yet their reliability is still unclear. Taking CsAgInBr as a representative, we have systemically investigated the defect properties of HDPs by theoretical calculations. First, we have determined the stable chemical potential regions to grow stoichiometric CsAgInBr without structural decomposition. Second, we reveal that Ag-rich and Br-poor are the ideal chemical potential conditions to grow n-type CsAgInBr with shallow defect levels. Third, we find the conductivity of CsAgInBr can change from good n-type, to poorer n-type, to intrinsic semiconducting depending on the growth conditions. Our studies provided important guidance for experiments to fabricate Pb-free perovskite-based solar cell devices with superior PV performances.
无铅卤化物双钙钛矿（HDPs）有望成为超越有机-无机卤化物钙钛矿的有前景的光伏（PV）材料，后者因结构不稳定性和毒性而受到阻碍。HDPs与缺陷和稳定性相关的特性对于将其用作重要的光伏吸收剂至关重要，但其可靠性仍不明确。以CsAgInBr为代表，我们通过理论计算系统地研究了HDPs的缺陷特性。首先，我们确定了生长化学计量比的CsAgInBr且无结构分解的稳定化学势区域。其次，我们揭示富Ag和贫Br是生长具有浅缺陷能级的n型CsAgInBr的理想化学势条件。第三，我们发现CsAgInBr的电导率会根据生长条件从良好的n型变为较差的n型，再变为本征半导体。我们的研究为制造具有卓越光伏性能的无铅钙钛矿基太阳能电池器件的实验提供了重要指导。
