Affiliation:
1. Photovoltaic Materials Group Center for Green Research on Energy and Environmental Materials National Institute for Materials Science Tsukuba Ibaraki 305-0047 Japan
2. Faculty of Pure and Applied Sciences University of Tsukuba Tsukuba Ibaraki 305-8577 Japan
Abstract
The photodecomposition of PbI2 in the perovskite halide structure has been identified as a primary reason for the rapid degradation of metal halide perovskite solar cells (PSCs) under continuous illumination. In particular, excess PbI2 on the surface of perovskite films reduces the stability of PSCs via several mechanisms that are still unelucidated. Herein, the influence of excess PbI2 on PSCs is investigated by varying the Au deposition rate, which results in different temperatures during the fabrication of PSCs, and then they are compared with stoichiometric PSCs. It is demonstrated that the anion exchange of Br− in perovskite and I− in excess PbI2 occurs at the grain boundary and interface of the perovskite layers induced by the high heating temperature, leading to a photoluminescence peak redshift and lower power conversion efficiency. Light illumination accelerates the exchange of Br− and I− between the perovskite layer and excess PbI2 induced by carrier accumulation at the interface and grain boundary, leading to the poor stability of the PSCs.
Subject
Electrical and Electronic Engineering,Energy Engineering and Power Technology,Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials