Moisture-Resistant Thermoplastic Polyurethane Encapsulation for Flexible Perovskite Solar Cells

With increasing global energy demand and environmental challenges, advancing efficient and stable renewable energy technologies is critical. Flexible perovskite solar cells (FPSCs) have emerged as a prominent research focus due to their exceptional power conversion efficiency (PCE) and cost effectiveness. However, the susceptibility of perovskite materials to moisture and oxygen hinders their commercial viability. This study proposes a novel encapsulation technique using transparent thermoplastic polyurethane (TPU) with low moisture permeability to enhance the stability and durability of FPSC. First, it is demonstrated that the TPU encapsulation process is compatible with the perovskite solar cells (PSC) module and lossless encapsulation can be achieved without degradation in efficiency. Second, through micromorphological characterization analysis, it is confirmed that TPU encapsulation can effectively prevent water–oxygen ingress, retard the decomposition of perovskite materials, and improve the stability of the film. The experimental results demonstrate that TPU-encapsulated PSCs retain 95% of their original PCE after 1000 h at 25 °C and 50% relative humidity (RH) and sustain 80% of the original efficiency after 200 h of underwater immersion. Finally, it is demonstrated that the TPU encapsulation has a significant advantage in terms of manufacture cost, which positively contributes to the commercialization of PSC.