Efficient monolithic perovskite/perovskite tandem solar cells are fabricated using two perovskite absorbers with complementary bandgaps. By employing doped organic semiconductors, an efficient and selective extraction of the charge carriers is ensured. This study demonstrates perovskite/perovskite tandem cells delivering a maximum efficiency of 18%, highlighting the potential of vacuum‐deposited multilayer structures in overcoming the efficiency of single‐junction perovskite devices.

Vacuum deposition is one of the most technologically relevant techniques for the fabrication of perovskite solar cells. The most efficient vacuum-based devices rely on doped organic contacts, compromising the long-term stability of the system. Here, we introduce an inorganic electron-transporting material to obtain power conversion efficiencies matching the best performing vacuum-deposited devices, with open-circuit potential close to the thermodynamic limit. We analyze the leakage current reduction and the interfacial recombination improvement upon use of a thin (<10 nm) interlayer of C, as well as a more favorable band alignment after a bias/ultraviolet light activation process. This work presents an alternative for organic contacts in highly efficient vacuum-deposited perovskite solar cells.

The addition of Sr in CH NH PbI perovskite films enhances the charge carrier collection efficiency of solar cells leading to very high fill factors, up to 85%. The charge carrier lifetime of Sr -containing perovskites is in excess of 40 μs, longer than those reported for perovskite single crystals.