Cation exchange strategy to construct nanopatterned Zn:NiO_x electrode with highly conductive interface for efficient inverted perovskite solar cells

Inorganic hole-transporting materials (HTMs) with excellent hole extraction and transfer properties are highly desirable for inverted perovskite solar cells (PSCs). However, the widely employed oxide HTMs (e.g., NiO_x nanocrystal) often suffer from the low p-type conductivity and severe trap-assisted recombination at HTMs/perovskite interface, which significantly limits the final performance of PSCs. Herein, the facile template-assisted cation exchange strategy is developed to fabricate nanopatterned Zn:NiO_x as efficient HTMs for PSCs, for the first time. Promisingly, by virtue of the advantageous 1D nanoscale architecture and synergistic substitutional Zn doping, high conductivity, high hole mobility and low interfacial charge trap states density have been achieved by such nanopatterned Zn:NiO_x HTMs. These features endow the highly conductive interface for PSCs to accelerate hole extraction and minimize recombination loss. As a consequence, PSCs with nanopatterned Zn:NiO_x deliver a champion efficiency of ≈20 % with open-circuit voltage of as high as 1.14 V. This work demonstrates and paves a new insight and avenue for the rational design of efficient oxide HTMs.