Energy Level Bending of Organic‐Inorganic Halide Perovskite by Interfacial Dipole

Cesium carbonate (Cs 2 CO 3 ) is a widely used interfacial modification material in organic solar cells (OSCs), organic light‐emitting diode (OLED) and so on, which can: 1) lower the work function of metal electrode; 2) induce n‐doping effect; and 3) alter the energy level of semiconductor materials under the action of dipole. Cs 2 CO 3 is selected in this study to modify the interface of perovskite solar cells (PSCs) and therefore improves the device performance. Further studies indicate that this performance improvement is due to the diffusion of Cs 2 CO 3 through [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) to form dipoles with perovskite to bend its energy level, resulting in an increased electron collection efficiency. This proposed mechanism for the interfacial modification of PSCs by bending the perovskite energy level through interfacial dipoles deepens the understanding of the role of interfacial layer.