In situ polymerization assisted strain release to enable efficient and mechanically robust flexible perovskite solar cells and minimodules

Abstract

Flexible perovskite solar cells (F-PSCs) exhibit much wider application scope due to the advantages of being light weight, portable, bendable, compatible with curved surfaces, etc. However, unsatisfactory efficiency and mechanical stability severely restrain their further development. Here, an interfacial adhesion strategy is reported to improve the mechanical stability of n-i-p-type F-PSCs. Poly-ECA is inserted between the perovskite layer and SnO₂ layer by the self-polymerization of ethyl α-cyanoacrylate (ECA) under mild conditions. Strong interactions between poly-ECA and the SnO₂/perovskite layer can enhance the mechanical strength of the buried interface. In addition, interfacial defects are also passivated and the energy level alignment at the perovskite interface bottom is optimized, thus facilitating charge transportation. Based on this interfacial adhesion strategy, 25.7% PCE has been achieved with a certified PCE of 25.04% for small-area flexible PSC devices, and 21.9% PCE has been obtained for large-area F-PSC modules (aperture area: 22.55 cm²). Additionally, device stability, particularly mechanical stability, has been significantly improved, and 95% of the initial efficiency can be maintained by small-area devices after 10 000 bending cycles. This work provides a simple, convenient way to simultaneously enhance the efficiency and stability of flexible devices.