Long-Term Stability In Gamma-Cspbi3 Perovskite Via An Ultraviolet-Curable Polymer Network

Black-colored (alpha, gamma-phase) CsPbI3 perovskites have a small bandgap and excellent absorption properties in the visible light regime, making them attractive for solar cells. However, their long-term stability in ambient conditions is limited. Here, we demonstrate a strategy to improve structural and electrical long-term stability in gamma-CsPbI3 by the use of an ultraviolet-curable polyethylene glycol dimethacrylate (PEGDMA) polymer network. Oxygen lone pair electrons from the PEGDMA are found to capture Cs+ and Pb2+ cations, improving crystal growth of gamma-CsPbI3 around PEGDMA. In addition, the PEGDMA polymer network strongly contributes to maintaining the black phase of gamma-CsPbI3 for more than 35 days in air, and an optimized perovskite film retained similar to 90% of its initial electrical properties under red, green, and blue light irradiation.