Effective n-type de-doping of perovskite surface via defect passivation and improved film crystallization for high-efficiency inorganic solar cells

Abstract

Defects in perovskite films not only challenge the efficiency and stability improvement of perovskite solar cells (PSCs), but also serve as electronic dopants that impact interface energetics and charge-transfer kinetics. To address this issue, herein, we introduced a natural additive into a perovskite precursor to improve the inorganic CsPbI₂Br film quality. Arising from the strong interaction between passivation molecules and undercoordinated Pb²⁺ in the perovskite, the reduction in defects results in effective n-type de-doping of the inorganic CsPbI₂Br perovskite surface, concomitantly forming an n/n⁻ homojunction at the top perovskite/carbon interface for accelerating charge extraction and suppressing carrier nonradiative recombination in a carbon-based PSC. Consequently, a cutting-edge efficiency as high as 15.0% was achieved with reduced hysteresis in addition to significantly improved long-term stability for a 65 days storage period in the air (94.74% efficiency retention rate) and persistent light irradiation for over 230 hours in N₂ (∼82% efficiency retention rate).