Multifunctional MgO Layer in Perovskite Solar Cells

A multifunctional magnesium oxide (MgO) layer was successfully introduced into perovskite solar cells (PSCs) to enhance their performance. MgO was coated onto the surface of mesoporous TiO2 by the decomposition of magnesium acetate and, therefore, could block contact between the perovskite and TiO2. X-ray photoelectron spectroscopy and infrared spectroscopy showed that the amount of H2O/hydroxyl absorbed on the TiO2 decreased after MgO modification. The UV/Vis absorption spectra of the perovskite with MgO modification revealed an enhanced photoelectric performance compared with that of unmodified perovskite after UV illumination. In addition to the photocurrent, the photovoltage and fill factor also showed an enhancement after modification, which resulted in an increase in the overall efficiency of the cell from 9.6 to 13.9%. Electrochemical impedance spectroscopy (EIS) confirmed that MgO acts as an insulating layer to reduce charge recombination.