2, University of North Carolina, Chapel Hill, North Carolina, United States
Organic-inorganic hybrid perovskite (OIHP) solar cells have achieved over 22% powder conversion efficiency, which are promising candidates for next generation of energy converter. However, the stability problems have hindered their commercialization. While encapsulation techniques have been developed to protect OIHP solar cells from external stimuli such as moisture, oxygen and ultraviolet light, understanding the intrinsic instability origin of perovskite films is needed to improve their stability.
In this talk, we will report the OIHP films fabricated by existing methods are strained, caused by mismatched thermal expansion of perovskite films and substrates during the thermal annealing process. The strain was characterized by both in-plane and out-of-plane XRD. The strain accelerates degradation of perovskite films under illumination, which can be explained by increased ion migration in strained OIHP films. This study points out an avenue to enhance the intrinsic stability of perovskite films and solar cells by reducing residual strain in perovskite films.