Near-Surface Sulfidation-Induced p-n Junction Enabling High-Efficiency Inverted Perovskite Solar Cells

Inverted perovskite solar cells (PSCs) often suffer from inefficient electron extraction due to the intrinsically p-type nature of the perovskite surface at the electron transport layer interface. Here, we report a near-surface sulfidation strategy using dibutyl sulfide (DBS) to induce a surface p-to-n transition, which creates a near-surface electric field that facilitates electron extraction and suppresses interfacial recombination. Simultaneously, the formation of Pb-S coordination bonds passivates undercoordinated Pb²⁺ defects, reducing nonradiative recombination losses. As a result, DBS-treated inverted PSCs achieve a champion power conversion efficiency of 26.28% with a high open-circuit voltage of 1.191 V. The treated devices also exhibit enhanced thermal stability, retaining 91% of their initial efficiency after more than 700 h of aging at 85 °C in a N₂ atmosphere. This work presents a simple yet effective surface engineering approach that simultaneously enhances both the efficiency and stability of inverted PSCs.