Large grain growth for hole-conductor-free fully printable perovskite solar cells via polyoxometalate molecular doping†
A large-grained perovskite film, with a crystal grain size of ca. 30–50 μm, was achieved by polyoxometalate-induced Ostwald ripening. Aiming at commercially-oriented fully printable hole-conductor-free perovskite solar cells, the power conversion efficiency of the device was significantly improved from 9.17% to 11.35% (average) via polyoxometalate molecular doping. This is because the large-grained perovskite film could effectively reduce bulk defects and charge recombination, thereby facilitating charge transport.