Li Xiao-Fen, Cheng Song-Qi, Zhou Yu-Qian, Ouyang Wen-Hong, Li Shunning, Liu Bai-Xin, Liu Jian-Bo
Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China.
School of Advanced Materials, Shenzhen Graduate School, Peking University, Shenzhen, 518055, China.
Small. 2022 Jul;18(29):e2202623. doi: 10.1002/smll.202202623. Epub 2022 Jun 26.
Despite the excellent optoelectronic properties, organic-inorganic hybrid perovskite solar cells (PSCs) still present significant challenges in terms of ambient stability. CsPbI Br, a member of all-inorganic perovskites, may respond to this challenge because of its inherent high stability against light, moisture, and heat, and therefore has gained tremendous attraction recently. However, the practical application of CsPbI Br is still impeded by the notorious phenomenon of photoinduced halide segregation. Herein, by applying first-principles calculations, the stability, electronic structure, defect properties, and ion-diffusion properties of the stoichiometric CsPbI Br (110) surface and that with the adsorption of KX (X = Cl, Br, I) are systematically investigated. It is found that the adsorbed KX can serve as an external substitute of the halogen vacancies on the surface, therefore inhibiting halogen segregation and improving the stability of the CsPbI Br surface. The KX can also eliminate deep-level defect states caused by antisites, thereby contributing to the promoted optoelectronic properties of CsPbI Br. The mechanistic understanding of surface passivation in this work can lay the foundation for the future design of CsPbI Br PSCs with optimized optoelectronic performance.
尽管有机-无机杂化钙钛矿太阳能电池（PSC）具有优异的光电性能，但在环境稳定性方面仍面临重大挑战。全无机钙钛矿的成员CsPbI Br，由于其对光、湿气和热具有固有的高稳定性，可能应对这一挑战，因此最近受到了极大的关注。然而，CsPbI Br的实际应用仍然受到光致卤化物偏析这一众所周知的现象的阻碍。在此，通过应用第一性原理计算，系统地研究了化学计量比的CsPbI Br（110）表面以及吸附KX（X = Cl、Br、I）后的表面的稳定性、电子结构、缺陷性质和离子扩散性质。研究发现，吸附的KX可以作为表面卤素空位的外部替代物，从而抑制卤素偏析并提高CsPbI Br表面的稳定性。KX还可以消除由反位引起的深能级缺陷态，从而有助于提升CsPbI Br的光电性能。这项工作中对表面钝化的机理理解可为未来设计具有优化光电性能的CsPbI Br PSC奠定基础。
