Feng Xiang Xiang, Liu Biao, Long Mengqiu, Cai Mengqiu, Peng YongYi, Yang Junliang
Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, Hunan, China.
School of Physics and Electronics Science, Hunan University, Changsha 410082, Hunan, China.
J Phys Chem Lett. 2020 Aug 6;11(15):6266-6272. doi: 10.1021/acs.jpclett.0c01870. Epub 2020 Jul 22.
The stability of perovskites is an urgent problem to be solved before commercialization. An ultrathin PbF layer covering the perovskite can be an effective strategy to improve the stability of the perovskite greatly. The perovskite/PbF interface (XPbI/PbF, X = Cs and MA) is constructed, and the structural and chemical properties are studied by first-principles calculations. The results show that PbF has better structural stability than the perovskites and can stabilize the octahedral frame of perovskite in the perovskite/PbF interface. The PbF layer reconstructs the XPbI surface, resulting in the perovskite PbI interface transforming into a more stable XI interface in the perovskite/PbF interface. Meanwhile, the tiny stress compression in the perovskite/PbF interface can enhance the stability of perovskite. The large affinity of F atoms can adsorb free Pb atoms and suppress deleterious ion migration. In addition, the XPbI/PbF interfaces have good dynamic stability at room temperature (300 K). Therefore, the PbF layer covering provides new ideas for the stability study of perovskites.
在商业化之前，钙钛矿的稳定性是一个亟待解决的问题。覆盖在钙钛矿上的超薄PbF层可能是一种有效策略，可极大地提高钙钛矿的稳定性。构建了钙钛矿/PbF界面（XPbI/PbF，X = Cs和MA），并通过第一性原理计算研究了其结构和化学性质。结果表明，PbF比钙钛矿具有更好的结构稳定性，并且可以在钙钛矿/PbF界面中稳定钙钛矿的八面体框架。PbF层重构了XPbI表面，导致钙钛矿PbI界面在钙钛矿/PbF界面中转变为更稳定的XI界面。同时，钙钛矿/PbF界面中的微小应力压缩可增强钙钛矿的稳定性。F原子的大亲和力可以吸附游离的Pb原子并抑制有害离子迁移。此外，XPbI/PbF界面在室温（300 K）下具有良好的动态稳定性。因此，覆盖的PbF层为钙钛矿的稳定性研究提供了新思路。
