Kye Yun-Hyok, Yu Chol-Jun, Jong Un-Gi, Chen Yue, Walsh Aron
Computational Materials Design (CMD), Faculty of Materials Science , Kim Il Sung University , Ryongnam-Dong, Taesong District, Pyongyang , Democratic People's Republic of Korea.
Department of Mechanical Engineering , The University of Hong Kong , Pokfulam Road , Hong Kong SAR , China.
J Phys Chem Lett. 2018 May 3;9(9):2196-2201. doi: 10.1021/acs.jpclett.8b00406. Epub 2018 Apr 16.
The chemical stability of methylammonium lead iodide (MAPbI) under humid conditions remains the primary challenge facing halide perovskite solar cells. We investigate defect processes in the water-intercalated iodide perovskite (MAPbI_HO) and monohydrated phase (MAPbI·HO) within a first-principles thermodynamic framework. We consider the formation energies of isolated and aggregated vacancy defects with different charge states under I-rich and I-poor conditions. It is found that a PbI (partial Schottky) vacancy complex can be formed readily, while the MAI vacancy complex is difficult to form in the hydrous compounds. Vacancies in the hydrous phases create deep charge transition levels, indicating the degradation of the lead halide perovskite upon exposure to moisture. Electronic structure analysis supports a mechanism of water-mediated vacancy pair formation.
在潮湿条件下，甲基碘化铅（MAPbI）的化学稳定性仍然是卤化物钙钛矿太阳能电池面临的主要挑战。我们在第一性原理热力学框架内研究了水插层碘化钙钛矿（MAPbI_HO）和一水合物相（MAPbI·HO）中的缺陷过程。我们考虑了在富碘和贫碘条件下不同电荷态的孤立和聚集空位缺陷的形成能。结果发现，PbI（部分肖特基）空位复合体很容易形成，而MAI空位复合体在含水化合物中很难形成。水相中的空位产生了深电荷跃迁能级，这表明卤化铅钙钛矿在暴露于湿气时会发生降解。电子结构分析支持了水介导的空位对形成机制。
