Complexation Engineering of Electron Transport Layers for High-Performance Perovskite Solar Cells

For high-performance perovskite solar cells (PSCs), transition metal complexes as modifiers are used to optimize the energy-level alignment of the SnO2 electron transport layer (ETL), reduce the defects at the ETL/perovskite interface, and improve the crystallinity of the perovskite layer. Herein, it is shown that application of [Ni(NH3)(6)]F-2 or [Co(NH3)(6)]F-2 complexes yields a substantially improved open-circuit voltage and fill factor, and thereby photoelectric conversion efficiency (PCE). The optimum PCEs of the [Ni(NH3)(6)]F-2- or [Co(NH3)(6)]F-2-treated PSCs reach 22.58% and 22.47%, respectively, which are much higher than that of the unmodified PSC (20.21%). This study provides a direction for improving the performance of a planar PSC using a complex-modified ETL.