Record‐Efficient Flexible Monolithic Perovskite–CIGS Tandem Solar Cell with VOC Exceeding 1.8 V on Polymer Substrate

Abstract Here, the surface modification of RF sputtering NiOx films by 4PADCB (NiOx‐P) is proposed for the first time. The modification effectively suppresses voltage loss at the hole transport layer (HTL)/perovskite interface and optimizes the energy band alignment between the perovskite layer and RF NiOx, thereby enhancing charge extraction and reducing nonradiative recombination of tandem devices, resulting in a flexible monolithic Perovskite (PVK)‐CIGS tandem solar cell with the highest efficiency of 22.8% and an extremely high Open‐circuit voltage (V OC ) of 1.82 V. This method is expected to obtain better flexible monolithic PVK‐CIGS tandem solar cells.