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

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 NiOx 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 NiOx HTL, the hole-extraction efficiency was limited by the unmatched valence band and too many surface defects of the NiOx layer, especially for the vacuum-deposited NiOx and perovskite. Herein, we developed a facile strategy to overcome this issue by using self-assembled glycine molecules to treat the NiOx surface. With glycine on the surface, the NiOx exhibited a deeper valence band maximum and a faster charge-extraction at the NiOx/perovskite interface. What's more, the vacuum-deposited perovskite showed a better crystallinity on the NiOx + 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.

Automated summary

Organic-inorganic hybrid perovskite solar cells (PSCs) have gained significant research attention due to their high efficiency and low cost. However, the use of expensive organic materials as hole-transport layers (HTLs) in PSCs with high efficiencies contradicts the low-cost concept. In this study, a facile strategy using self-assembled glycine molecules to treat the NiOx surface was developed to overcome the limitations of NiOx as an HTL. The treated NiOx exhibited improved charge extraction efficiency and resulted in PSCs with higher crystallinity and champion power conversion efficiency (PCE) of 17.96%.