Growth of 1D Nanorod Perovskite for Surface Passivation in FAPbI Perovskite Solar Cells.

The regulation of perovskite crystallization and nanostructure have revolutionized the development of high-performance perovskite solar cells (PSCs) in recent years. Yet the problem of stably passivating perovskite surface defects remains perplexing. The 1D perovskites possess superior physical properties compared with bulk crystals, such as excellent moisture stability, self-healing property, and surface defects passivation. Here, 4-chlorobenzamidine hydrochloride (CBAH) is developed as spacer to form orientationally crystallized nanorod-like 1D perovskite on the top surface of 3D perovskite for surface passivation of FAPbI perovskite. Further structure characterizations indicate the coexistence of 1D-3D hybrid perovskite lattices in nanorod-like perovskite passivation layer, which regulates the crystallization and morphology effectively and assists in promoting charge extraction, and suppressing charge recombination. As a result, the CBAH treated FAPbI -based PSCs exhibit a boosted power conversion efficiency of 21.95%. More importantly, the resultant unencapsulated devices display improved thermal, moisture, and illumination stability, and high reproducibility in terms of device performance. These results indicate the potential of organic halide salts for regulation of perovskite crystallization, offering a promising route of utilizing 1D perovskites nanorods in photovoltaic fields.