Colloidal Self-Assembly of CuCrO₂ Nanocrystals for Durable Inverted Perovskite Solar Cells

Despite the promise of self-assembled organic hole-transport layers (HTLs) in inverted perovskite solar cells, critical concerns persist about their structural stability under external fields such as bias and illumination, which have been regarded as a potential threat to the device's longevity. To address this issue, instead of using self-assembled organic molecules, the intrinsically stable p-type, wide bandgap CuCrO₂ colloidal nanocrystals with high monodispersity are synthesized and self-assembled them into HTL via a simple dip-coating method. By further HCl-mediated ligands exchange, the self-assembled CuCrO₂-HTL creates a thermally stable chlorinated surface that can not only enhance the electronic coupling of inter nanocrystals but also provide contact passivation on the perovskite surface defects. These merits eventually endow the constructed buried interface with favorable contact, thus facilitating efficient and stable hole transfer. Consequently, an impressive power conversion efficiency of 25.35% is achieved, accompanied by greatly improved longevity under different accelerated-aging tests.