Silicon/nickel oxide core/shell nanospheres as a hole transport layer for high efficiency and light-stable perovskite solar cells.

Metal halide perovskite solar cells (PSCs) possess huge potential due to their high power conversion efficiency. However, instability is still a key factor limiting their applications. Therefore, we have found a feasible strategy to improve the light stability of PSCs. Specifically, a core-shell material with a silicon nanosphere core and a nickel oxide nanosheet shell serves as the hole transport layer in our PSCs. Due to the selective absorption of ultraviolet light by the silicon nanoparticles, the ultraviolet light content of the natural light that reaches the perovskite layer is reduced. Compared with a control device (without Si), the PSCs with the silicon/nickel oxide hole transport layer possessed a higher current density of 22.09 mA cm-2 and a higher power conversion efficiency of 18.54%, with both values increased by 2.7% and 6.1%, respectively. More importantly, the PSCs based on a silicon/nickel oxide hole transport layer maintains 85% of its initial power conversion efficiency value after 700 hours of natural light exposure. These results indicate that the silicon/nickel oxide hole transport layer is an important functional component of the PSCs, which improves the photovoltaic performance and reduces ultraviolet light-induced photodegradation, thereby improving the device stability.