Slow Spontaneous Efficiency Enhancement of Single-Crystal Perovskite Solar Cells Due to Trapped Solvent
Vishal Yeddu, Parinaz Moazzezi, Bekir Türedi, Muhammad Naufal Lintangpradipto, Dongyang Zhang, Soumya Kundu, Deepak Thrithamarassery Gangadharan, Reuven Gordon, Osman M. Bakr, Makhsud I. Saidaminov
Abstract
Perovskite solar cells show spontaneous efficiency enhancement (SEE), i.e., their efficiency improves with time over a few days. Many mechanisms have been proposed for explaining such behavior in polycrystalline perovskite solar cells. However, such studies have not been performed on single-crystal perovskite solar cells. Here, we report our observation of slow (∼20 days) SEE in methylammonium lead iodide single-crystal perovskite solar cells. We found that the SEE is due to the slow escape of solvent trapped by the perovskite single-crystal thin films. We show that this process can be substantially accelerated by heat treatment of cells at 40 °C. This work provides a ground for fast-tracking the progress of single-crystal perovskite solar cells.