Interfacial engineering with carbon–graphite–Cu(δ)Ni(1−δ)O for ambient-air stable composite-based hole-conductor-free perovskite solar cells

Ambient air atmosphere is inimical to organic–inorganic halide perovskites and organic hole transport materials, and is, thus, necessarily avoided during device fabrication. To solve this issue, it is highly desirable to design stable perovskite-based composites and device configurations. Here, fully ambient-air and antisolvent-free-processed, stable and all-inorganic metal-oxide selective contact hole-conductor-free perovskite solar cells (HCF-PSCs) based on perovskite-based composites with an interfacial engineering strategy are reported. The formation of perovskite-based composites by interfacial engineering with carbon–graphite–Cu(δ)Ni(1−δ)O not only improved interfacial contacts, charge extraction and transport but also passivated trap states of perovskite thin films and charge recombination at the interfaces. Thus, such perovskite composites with interfacial engineering-based HCF-PSCs without encapsulation showed excellent stability by sustaining 94% of initial PCE over 300 days under ambient conditions.