Ghosh Paheli, Spencer Ben F, Krishnan Jagadamma Lethy
Energy Harvesting Research Group, School of Physics & Astronomy, SUPA, University of St Andrews, St Andrews KY16 9SS United Kingdom.
Henry Royce Institute and Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
ACS Appl Energy Mater. 2024 Oct 8;7(20):9045-9051. doi: 10.1021/acsaem.4c01898. eCollection 2024 Oct 28.
Understanding the vertical compositional homogeneity and defect distribution is of paramount importance in elucidating and maximizing the performance of halide-perovskite-based optoelectronic devices. This work reports the depth-dependent study of the chemical composition and metallic Pb content of all-inorganic CsPbIBr perovskite films undertaken using lab-based hard X-ray photoelectron spectroscopy and soft X-ray photoelectron spectroscopy. The presence of elemental or metallic Pb (Pb), in the bulk and at the surface of the perovskite films highlights the formation of defect or recombination centers throughout the analyzed depth. The Pb content was found to be of higher concentration in the bulk of the CsPbIBr films compared to that at the surface. Engineering the CsPbIBr film growth using appropriate antisolvents resulted in the overall reduction and/or complete elimination of Pb at the surface and at the bulk of the perovskite films. However, the effect of antisolvent treatment was significantly pronounced in the bulk-like region as compared to that at the surface. Pb is synonymous with defect states/recombination centers in perovskite films and this reduction in defect density due to the antisolvent treatment corroborates the enhanced phase stability and improved solar cell performance of the corresponding CsPbIBr devices.
了解垂直成分均匀性和缺陷分布对于阐明和最大化基于卤化物钙钛矿的光电器件的性能至关重要。这项工作报告了使用基于实验室的硬X射线光电子能谱和软X射线光电子能谱对全无机CsPbIBr钙钛矿薄膜的化学成分和金属Pb含量进行的深度依赖性研究。在钙钛矿薄膜的本体和表面存在元素态或金属态Pb（Pb），这突出表明在整个分析深度都形成了缺陷或复合中心。研究发现，CsPbIBr薄膜本体中的Pb含量高于其表面的Pb含量。使用适当的反溶剂来调控CsPbIBr薄膜的生长，可使钙钛矿薄膜表面和本体中的Pb总体减少和/或完全消除。然而，与表面相比，反溶剂处理在类似本体区域的效果更为显著。Pb是钙钛矿薄膜中缺陷态/复合中心的代名词，这种由于反溶剂处理导致的缺陷密度降低证实了相应CsPbIBr器件的相稳定性增强和太阳能电池性能改善。
