Bifunctional modification towards LaNiO₃/Perovskite interface for enhanced performance in perovskite solar cells

Nickel oxide (NiO_x) hole-transport layers (HTLs) in inverted perovskite solar cells (PSCs) suffer from interfacial energy level misalignment and lattice mismatch. This work introduces lanthanum nickelate (LaNiO₃, LNO) as a superior HTL alternative and further enhances its performance through a bifunctional interfacial modification. We employ cobalt acetate (Co(OAc)₂) at the LNO/perovskite interface, where Co²⁺ dopants improve LNO conductivity by generating oxygen vacancies, while OAc^- ions passivate uncoordinated Pb²⁺ defects in the perovskite. This dual-action strategy simultaneously optimizes energy level alignment and enhances perovskite film quality, reducing interfacial recombination. Consequently, the power conversion efficiency for the modified MAPbI₃-based devices achieve a relative enhancement of 8% compared to control cells. This study demonstrates the significant potential of LNO and provides a generalizable interface engineering approach for high-performance inverted PSCs.