Uniform Coverage Functional Layers Enable High-Efficient Flexible Perovskite Solar Modules with an Outstanding Fill Factor

Uniform and pinhole-free functional layers are essential for high-efficient flexible perovskite solar modules (FPSMs). However, the poor wettability of self-assembled monolayers (SAMs) with carbazole bodies and phosphonic acid binding groups usually leads to porous large-area perovskite films. Herein, a layer of nickel oxide nanoparticles is inserted between sputtered nickel oxide and the SAM to increase the surface energy, and thus simultaneously improving the wettability and nucleation of the perovskite during vacuum-quenching method. Following this strategy, the best flexible perovskite solar cells with an active area of 0.09 cm(2) achieve a power conversion efficiency (PCE) of 21.97% under 1 sun illumination. In addition, FPSMs with the same structure exhibit a high fill factor approach 80% and reach a champion PCE of 19.71% on 58.14 cm(2) active area and a certified PCE of 18.17% on 61.26 cm(2) aperture area, which is the highest recorded PCE to the best knowledge. Furthermore, the optimized interface also enhances the adhesion between hole-transport layer and perovskite, and the encapsulated device retains 95% of its initial PCE after 1000 cycles under a 2 cm bending radius.