Perovskite Nanocrystals Reinforce UV‐Curable Encapsulation for Highly Stable Perovskite Solar Cells

Enhancing the encapsulation performance of ultraviolet (UV)‐curable adhesives is crucial for perovskite solar cells (PSCs). While the incorporation of nanomaterials has significantly improved the moisture resistance of adhesives and suppressed lead leakage from devices, the influence of nanomaterial morphology on UV‐curable adhesive performance remains poorly understood. Moreover, the mechanisms by which uncured adhesive monomers are prevented from penetrating into perovskite layers are still unclear. Herein, we report a strategy of incorporating perovskite nanocrystals—quantum dots (CsPbI ₃ ‐QDs), nanorods (CsPbI ₃ ‐NRs), and nanosheets (CsPbBr ₃ ‐NSs)—into polyurethane acrylate (PUA) UV‐curable adhesives to improve the encapsulation stability of PSCs. Through coordination interactions between nanocrystals and PUA monomers, the infiltration of uncured monomers into the perovskite layer is significantly suppressed. Leveraging size effects and UV absorption capabilities, optimized PUA/CsPbI ₃ ‐QDs‐encapsulated devices retained 87% of initial power conversion efficiency (PCE) after 1632 h at 55%–65% relative humidity, and 93% after 200 min UV exposure (365 nm), significantly higher than the control one (66% and 75%). Notably, lead leakage decreased by 85.6% (from 10.2 to 1.47 mg) for PUA/CsPbBr ₃ ‐NSs‐encapsulated devices after 77‐day water immersion. This work shows that nanocrystal additives with tailored morphologies represent a promising route toward highly stable and environmentally friendly PSC encapsulation.