Nickel oxide for inverted structure perovskite solar cells

Abstract

The emergence of inverted perovskite solar cells (PSCs) has attached great attention derived from the potential in improving stability. Charge transporting layer, especially hole transporting layer is crucial for efficient inverted PSCs. Organic materials were used as hole transporting layer previously. Recently, more and more inorganic hole transporting materials have been deployed for further improving the device stability. Nickel oxide (NiO x ) as p-type metal oxide, owning high charge mobility and intrinsic stability, has been widely adopted in inverted PSCs. High performance over 20% efficiency has been achieved on NiO x base inverted PSCs. Herein, we have summarized recent progresses and strategies on the NiO x based PSCs, including the synthesis or deposition methods of NiO x , doping and surface modification of NiO x for efficient and stable PSCs. Finally, we will discuss current challenges of utilizing NiO x HTLs in PSCs and attempt to give probable solutions to make further development in efficient as well as stable NiO x based PSCs. Nickel oxide is a promising hole transporting material for stable perovskite solar cells. However, the low electric conductivity and the mismatched energy level alignment of NiO x have restricted the efficiency of NiO x based device. Doping and surficial modification are considered key measures to address these drawbacks. This review systematically sorts out the effective strategies for improving NiO x in recent years and gives a future outlook.