The CuI/NiO gradient hole transport layer for enhanced carrier efficiency in large-area perovskite solar cell

The Cs0.05FA0.95PbI3-based solar cell (10 × 10 cm2) with a CuI/NiO bilayer gradient hole transport layer (HTL) is prepared via an approach of sputtering–in situ iodization–annealing method. The large-area CsFA-based solar cell with CuI/NiO HTLs exhibits a high power conversion efficiency (PCE) of ∼19.76% (active area: 96.5 cm2), showing good stability of ∼90.84% after ∼1000 h of aging. The CuI/NiO bilayer gradient HTL is regarded as the core issue, because, besides barrier amelioration and potential gradient construction, it exhibits high hole induction via charge compensation, while achieving effective hole extraction and electron retardation by Fermi level regulation, thereby improving carrier dynamics transportation for increasing PCE, including rapid carrier transfer, showing lower photodegradation for good long-term stability.