Multifunctional entinostat enhances the mechanical robustness and efficiency of flexible perovskite solar cells and minimodules.

Flexible perovskite solar cells have attracted substantial attention owing to their promises for soft and high power–weight compatibility. However, the inferior quality of the buried perovskite–substrate interface due to low interfacial adhesion and large deformation of flexible substrates have greatly limited the performance of flexible perovskite solar cells. Here we add the organic molecule entinostat into the hole extraction material poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) to enhance adhesion at the perovskite–substrate interface using the interaction of entinostat with perovskites, poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) and indium tin oxide through its multiple functional groups. In addition, entinostat reduces the density of voids at the bottom of the perovskite film owing to its capability to tune the crystallization of perovskites. We demonstrate inverted small-area flexible perovskite solar cells with a power conversion efficiency of 23.4%. Flexible perovskite minimodules with an area of 9 cm² achieve a certified aperture efficiency of ~19.0%. The optimized unencapsulated flexible minimodule retains 84% of its initial efficiency after 5,000 bending cycles and 90% of the initial power conversion efficiency after light soaking for >750 h. The organic molecule entinostat improves adhesion between the perovskites and substrates, leading to mechanically robust solar cell minimodules with an area of 9 cm² and power conversion efficiency of 19%. [ABSTRACT FROM AUTHOR]