Perovskite heterojunction based on CH₃NH₃PbBr₃ single crystal for high-sensitive self-powered photodetector

Perovskite single crystals exhibit extraordinary optoelectronic performances due to their advantages such as low trap-state densities, long carrier diffusion, and large absorption coefficient, and thus, photodetectors based on perovskite single crystals have attracted much research interest. Unlike the reported one-component single-crystal perovskite photodetectors, here, we have developed a facile two-step approach to fabricate a core-shell heterojunction based on the CH₃NH₃PbBr₃ single crystal. A photodetector made of the as-prepared perovskite heterojunction renders the feature of self-power attributed to a built-in electric field in the junction and exhibits a wavelength-dependent responsivity with a peak responsivity up to 11.5 mA W⁻¹ under 450 nm irradiation at zero bias, which is one order of magnitude higher than the CH₃NH₃PbBr₃ single crystal and shows a maximum external quantum efficiency of 3.17%, also higher than the reported 0.2% of the CH₃NH₃PbBr₃ single crystal. Our work may lead to more efficient self-powered heterojunction systems based on perovskite single crystals.