Origins of perovskite solar cell degradation under dry ambient storage in arid climates

To utilize the hybrid organic–inorganic halide perovskites more usefully in real-life optoelectronic devices, it is crucial to figure out what causes them to be inherently unstable. We discuss here the degradation mechanisms of double cation perovskite solar cells aged over five years and exposed to dry conditions, and the most significant stress factors are temperature and humidity. Our study protocol leads to the finding that long-term exposure leads to lattice distortion and localized grain boundary strain, which came about by our model that strengthens defects and loss of halides. All these processes cause a high rate of degradation and a substantial lowering of the performance of solar cells. Interestingly, the experiments of annealing prove that damaged films, even after five years of exposure in air, preserve some part of the crystallinity of the perovskite phase and much of the crystallization of lead iodide (PbI2). These findings not only prove the crucial role of lattice and interfacial unsteadiness due to the environment in dry climatic circumstances but also provide practical understanding on the way to prepare perovskite solar cells with enhanced stability in the arid and desert environments.