Solvent‐Free Thiol‐Ene Photopolymerization for Non‐Destructive Encapsulation of Perovskite Solar Cells

Abstract Achieving long‐term operational stability remains a critical barrier to the commercialization of perovskite solar cells (PSCs). In this work, a solvent‐free, room‐temperature encapsulation strategy is presented using a thiol‐ene click photopolymerized siloxane material (TECP) specifically designed for PSC protection. TECP cures rapidly under UV light (<30 s at 25 °C) and forms a dense, hydrophobic, and mechanically robust network with high optical transparency and minimal thermal stress. Unlike conventional acrylate‐ or epoxy‐based UV‐curable adhesives, TECP exhibits strong interfacial adhesion, complete polymerization, and excellent chemical inertness without releasing residual monomers or solvents. The power conversion efficiencyof TECP‐encapsulated devices remains virtually unchanged (25.49% before versus 25.41% after encapsulation), highlighting the benign nature of the TECP encapsulation process. In addition, these devices exhibit remarkable environmental stability, retaining 91.5% and 94.0% of their initial efficiency after 1100 h of damp heat aging (85% RH, 65 °C) and 250 thermal cycles (−40 to 85 °C), respectively. These results establish TECP as a scalable and non‐destructive encapsulation solution that effectively mitigates environmental and thermal degradation, facilitating the practical implementation of high‐efficiency PSCs.