Studying the impact of different parylene derivatives on perovskite solar cells stability

This study evaluates the effectiveness of parylene derivatives as encapsulation materials for enhancing the stability of perovskite solar cells (PSCs). The research compares four types of parylene (N, C, D, and F) based on their ability to protect perovskite films and prevent PSC degradation under high temperature and humidity conditions. Experimental results indicate that parylene-C offers superior barrier properties, effectively suppressing perovskite decomposition under prolonged illumination and elevated temperatures in an ambient environment. Parylene-N demonstrates exceptional performance in encapsulating complete PSCs, achieving dark ambient storage stability for more than 10 000 h with minimal efficiency losses (2%) during dark ambient storage. Despite superior water barrier properties, chlorine-containing parylene derivatives (C and D) are found to be unsuitable for solar cells with silver top electrodes due to silver ion diffusion, resulting in device failure. In contrast, fluorinated parylene-F avoids this issue but shows lower moisture resistance. The findings emphasize the importance of material compatibility and suggest that unsubstituted parylene-N is the best candidate for PSC encapsulation in the case of silver electrodes and relatively low air humidity (RH < 35%).