Highly efficient wide-bandgap perovskite solar cells prepared by fixing charge passivation in the interface layer

The severe stress on the surface of the wide-bandgap perovskite film will extend to the carrier transport layer (CTL)/metal electrode interface, leading to increased roughness of the CTL surface. This, in turn, adversely affects carrier transfer at the interface and compromises device stability. To address this issue, we devised a localized contact structure wherein molybdenum oxide (MoOx) interlayers of specific thickness were vacuum-deposited at the CTL/metal electrode interface to change the path of carrier transfer. Characterizations of the MoOx localized contact structure were done by Kelvin probe force microscopy, capacitance–voltage (C–V), electrochemical impedance spectroscopy, and x-ray photoelectron spectroscopy. It was observed that MoOx interlayer can generate negative fixed charges at hole transport layer/Ag interface, which changes the carrier concentration distribution, enhances the built-in voltage, and promotes the transfer of carriers near the interface. Compared to wide-bandgap perovskite solar cells (WB-PSCs, Eg = 1.65 eV) lacking the MoOx localized contact structure, the efficiency of the optimized device increased to 20.5%, accompanied by enhancements in overall performance parameters. Notably, the thermal and light stability of the unpackaged devices have been significantly improved.