Turning off 2D reconstruction with a sulfone-modified passivator for efficient and stable inverted perovskite solar cells

Abstract

Organic ammoniums are broadly employed for defect passivation in perovskite solar cells (PVSCs), but reactive passivators often trigger unstable 3D to 2D surface reconstruction, degrading device performance under thermal and light stress. Here, we turn off the 2D reconstruction at the perovskite surface with a sulfone-modified passivator of thiomorpholine-1,1-dioxide hydroiodide (SMDORI). This sulfone-modified ammonium passivator integrates geometric matching, strong sulfonyl Pb²⁺ coordination, and a favorable adsorption orientation, thereby suppressing reconstructive reactivity toward 2D formation while retaining strong surface binding. Incorporated into inverted PVSCs, SMDORI achieves a champion power conversion efficiency (PCE) of 25.21% and delivers significantly enhanced operational stability, retaining >95% of its initial efficiency after 1500 hours under dark storage (ISOS-D-1), 91% after heating at 65 °C for 1500 hours (ISOS-D-2), and a T₈₀ of 340 h under continuous one-sun illumination at the maximum power point (ISOS-L-1). This work provides a practical molecular design route for ammonium passivators to reconcile high efficiency with long-term stability in inverted PVSCs.