Mechanically Robust and Flexible Perovskite Solar Cells via a Printable and Gelatinous Interface

Dramatic development in perovskite solar cells (PSCs) and the widespread application of wearable electronics have attracted extensive research in the area of large-scale flexible solar power sources based on PSCs. Manufacturing of flexible PSCs by printing is considered to be one of the most potential methods. However, it is still a great challenge to print large-area uniform hole transport layers (HTLs) on a rough and soft plastic substrate to achieve flexible PSCs with high efficiency and good stability. Herein, we synthesized a viscous poly(3,4-ethylene dioxythiophene):graphene oxide (PEDOT:GO) gel and then blade-coated the gel by high-speed shearing to achieve high-quality HTLs with scalable size. The glued HTLs exhibit high viscosity, electrical conductivity, and mechanical flexibility, which enhance the adhesive ability and protect the brittle ITO electrode and perovskite crystals. Due to the gelatinous HTLs, we achieved an optimal efficiency of the flexible PSCs (1.01 cm²) of 19.7%, while that of the large-area flexible perovskite module (25 cm²) exceeded 10%. This is the highest efficiency for reported flexible MAPbI₃ PSCs (1.01 cm²). Furthermore, the efficiency retention of the PSCs remains over 85% after 5000 bending cycles, which is of great significance for the practical application of PSCs in portable and wearable electronics.