All-vacuum deposited perovskite solar cells with glycine modified NiOx hole-transport layers

Abstract

Organic–inorganic hybrid perovskite solar cells (PSCs) have attracted enormous research attention due to their high efficiency and low cost. However, most of the PSCs with high efficiencies still need expensive organic materials as their hole-transport layer (HTL). Obviously, the highly expensive materials go against the low-cost concept of advanced PSCs. In this regard, inorganic NiO_x was considered as an idea HTL due to its good transmittance in the visible region and outstanding chemical stability. But for most of the PSCs with a NiO_x HTL, the hole-extraction efficiency was limited by the unmatched valence band and too many surface defects of the NiO_x layer, especially for the vacuum-deposited NiO_x and perovskite. Herein, we developed a facile strategy to overcome this issue by using self-assembled glycine molecules to treat the NiO_x surface. With glycine on the surface, the NiO_x exhibited a deeper valence band maximum and a faster charge-extraction at the NiO_x/perovskite interface. What's more, the vacuum-deposited perovskite showed a better crystallinity on the NiO_x + glycine substrate. As a result, the PSCs with a glycine interfacial layer achieved a champion PCE of 17.96% with negligible hysteresis. This facile approach is expected to be further developed for fabricating high-efficiency PSCs on textured silicon solar cells.