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 scenarios due to the advantages of light-weight, portability, bendable and compatible with curved surfaces etc. However, unsatisfactory efficiency and mechanical stability severely restrain its further development. Here, an interfacial adhesion strategy is reported to improve mechanical stability of n-i-p typed F-PSCs. A poly-ECA is inserted between the perovskite layer and SnO2 layer by self-polymerization of ethyl α-cyanoacrylate (ECA) under a mild condition. Strong interactions between poly-ECA and SnO2/perovskite layer can enhance the mechanical strength of the buried interface. In the meantime, 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 stabilities, particularly mechanical stability, has been significantly improved, 95% of its initial efficiency can be maintained for small-area devices after 10000 bending cycles. This work provides a simple, convenient way to simultaneously enhance the efficiency and stability of flexible devices.