Guo Lei, Xu Gao, Tang Gang, Fang Daining, Hong Jiawang
School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, People's Republic of China.
Nanotechnology. 2020 May 29;31(22):225204. doi: 10.1088/1361-6528/ab7679. Epub 2020 Feb 14.
In recent years, organic-inorganic hybrid perovskites have attracted wide attention due to their excellent optoelectronic properties in the application of optoelectronic devices. In the manufacturing process of perovskite solar cells, perovskite films inevitably have residual stress caused by non-stoichiometry components and the external load. However, their effects on the structural stability and photovoltaic performance of perovskite solar cells are still not clear. In this work, we investigated the effects of external strain on the structural stability and optoelectronic properties of tetragonal MAPbI by using the first-principles calculations. We found that the migration barrier of I ion increases in the presence of compressive strain and decreases with tensile strain, indicating that the compressive strain can enhance the structural stability of halide perovskites. In addition, the light absorption and electronic properties of MAPbI under compressive strain are also improved. The variations of the band gap under triaxial and biaxial strains are consistent within a certain range of strain, resulting from the fact that the band edge positions are mainly influenced by the Pb-I bond in the equatorial plane. Our results provide useful guidance for realizing the commercial applications of MAPbI-based perovskite solar cells.
近年来，有机-无机杂化钙钛矿因其在光电器件应用中优异的光电性能而备受关注。在钙钛矿太阳能电池的制造过程中，钙钛矿薄膜不可避免地会因非化学计量比成分和外部负载而产生残余应力。然而，它们对钙钛矿太阳能电池结构稳定性和光伏性能的影响仍不明确。在这项工作中，我们通过第一性原理计算研究了外部应变对四方相MAPbI结构稳定性和光电性能的影响。我们发现，在存在压缩应变时I离子的迁移势垒增加，而在拉伸应变下降低，这表明压缩应变可以增强卤化物钙钛矿的结构稳定性。此外，压缩应变下MAPbI的光吸收和电子性质也得到改善。在一定应变范围内，三轴和双轴应变下带隙的变化是一致的，这是由于带边位置主要受赤道平面内Pb-I键的影响。我们的结果为实现基于MAPbI的钙钛矿太阳能电池的商业应用提供了有用的指导。
