Dual-Passivation Strategy of Bulk and Surface Enables Highly Efficient and Stable Inverted Perovskite Solar Cells.

Abstract

Inverted perovskite solar cells (PSCs) have captured significant interest due to their outstanding stability, cost-effective fabrication process, and good compatibility with flexible and tandem devices. The presence of bulk and surface defects is key factor in PSCs that cause non-radiative recombination and degradation. To improve the efficiency and stability of inverted PSCs, a bulk-to-surface dual-passivation strategy is employed by utilizing Oleylamine Iodide (OAmI) as additives and 4-Fluorobenzylamine Hydroiodide (4-F-PMAI) as surface passivating agents. Utilizing OAmI as bulk passivation can enhance the crystallinity of perovskite films and reduce lattice defects. Meanwhile, 4-F-PMAI further suppresses non-radiative recombination and reduces open-circuit voltage (V_OC) loss through bidentate anchoring. Consequently, the dual-passivation strategy significantly enhances device performance, boosting the power conversion efficiency (PCE) of PSCs to 24.26%, with a V_OC of 1.15V. Moreover, the unencapsulated PSCs show excellent long-term stability maintaining over 85% and 90% of the initial efficiency under 85 °C thermal annealing in N₂ for 1000 hours and after storage in ambient conditions (RH: 30 ± 5%) for 1000 hours.