Locally MoO3-induced CsPbBr3 homojunction photodetectors with improved photoelectric performance

Perovskite-based semiconductor photodetectors have attracted wide attention in the photoelectric fields. By local MoO3 induction, MoO3:CsPbBr3−CsPbBr3 homojunction photodetector was constructed by chemical vapor deposition, exhibiting not only excellent response speed in the scale of microsecond, but also high responsivity of 247.1 A W−1 and detectivity (8.7 × 1012 Jones), roughly an order of magnitude higher than that of CsPbBr3 devices. Ultraviolet photoelectron spectroscopy measurements show that the Fermi level moves closer to the top of the valence band due to the local MoO3 induction, leading to the conversion of weak p-type CsPbBr3 to a strong p-type semiconductor, which is consistent with the calculation result based on density functional theory (DFT). The band alignment in the homojunction accelerates the photo-generated carrier separation and transfer, thus improving the photoelectric performance of MoO3:CsPbBr3−CsPbBr3 homojunction. Our results provide a new strategy to design photodetectors with excellent performance by constructing homojunctions with perovskite on different substrates.