混合卤化物钙钛矿固体中应变激活的光致卤化物偏析
Strain-activated light-induced halide segregation in mixed-halide perovskite solids.
作者信息
Zhao Yicheng, Miao Peng, Elia Jack, Hu Huiying, Wang Xiaoxia, Heumueller Thomas, Hou Yi, Matt Gebhard J, Osvet Andres, Chen Yu-Ting, Tarragó Mariona, de Ligny Dominique, Przybilla Thomas, Denninger Peter, Will Johannes, Zhang Jiyun, Tang Xiaofeng, Li Ning, He Chenglin, Pan Anlian, Meixner Alfred J, Spiecker Erdmann, Zhang Dai, Brabec Christoph J
机构信息
Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Martensstraße 7, 91058, Erlangen, Germany.
Institute of the Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 15, Tübingen, 72076, Germany.
出版信息
Nat Commun. 2020 Dec 10;11(1):6328. doi: 10.1038/s41467-020-20066-7.
Light-induced halide segregation limits the bandgap tunability of mixed-halide perovskites for tandem photovoltaics. Here we report that light-induced halide segregation is strain-activated in MAPb(IBr) with Br concentration below approximately 50%, while it is intrinsic for Br concentration over approximately 50%. Free-standing single crystals of CHNHPb(IBr) (35%Br) do not show halide segregation until uniaxial pressure is applied. Besides, 35%Br single crystals grown on lattice-mismatched substrates (e.g. single-crystal CaF) show inhomogeneous segregation due to heterogenous strain distribution. Through scanning probe microscopy, the above findings are successfully translated to polycrystalline thin films. For 35%Br thin films, halide segregation selectively occurs at grain boundaries due to localized strain at the boundaries; yet for 65%Br films, halide segregation occurs in the whole layer. We close by demonstrating that only the strain-activated halide segregation (35%Br/45%Br thin films) could be suppressed if the strain is properly released via additives (e.g. KI) or ideal substrates (e.g. SiO).
光致卤化物偏析限制了用于串联光伏的混合卤化物钙钛矿的带隙可调性。在此我们报告，在溴浓度低于约50%的MAPb(IBr)中，光致卤化物偏析是应变激活的，而对于溴浓度超过约50%的情况，它是固有的。CHNHPb(IBr)（35%溴）的独立单晶在施加单轴压力之前不会出现卤化物偏析。此外，在晶格失配衬底（如单晶CaF）上生长的35%溴单晶由于异质应变分布而表现出不均匀偏析。通过扫描探针显微镜，上述发现成功地转化到了多晶薄膜上。对于35%溴的薄膜，由于边界处的局部应变，卤化物偏析选择性地发生在晶界处；而对于65%溴的薄膜，卤化物偏析发生在整个层中。我们最后证明，如果通过添加剂（如KI）或理想衬底（如SiO）适当释放应变，只有应变激活的卤化物偏析（35%溴/45%溴薄膜）才能被抑制。
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