Strongly Enhanced Photoluminescence and Photoconductivity in Erbium-Doped MAPbBr₃ Single Crystals

B-site doping of organic–inorganic perovskites is an effective way to improve its optoelectronic properties; however, it is rarely reported for perovskite single crystals. Here, we report the B-site doping of MAPbBr₃ single crystals with erbium (Er) via a simple antisolvent vapor-assisted crystallization method. The Er-doped MAPbBr₃ single crystal exhibits significantly enhanced photoluminescence (PL) and photoconductivity compared with the undoped sample. Low-temperature PL spectroscopy reveals that Er-doping creates a shallow acceptor level inside the band gap of MAPbBr₃, which contributes to significantly enhanced PL emission because of bound excitons. Furthermore, Er-doping also effectively lowers the deep trap density and improves the conductivity and mobility of the single crystal. Consequently, the Er-doped MAPbBr₃ single crystal photodetector shows responsivity and external quantum efficiency approximately 5 times higher than those of the undoped device. The effective improvement of optoelectronic properties of the MAPbBr₃ single crystal by Er-doping may benefit a wide range of devices including photodetectors, light-emitting diodes, and lasers.