Advanced Self-powered Visible-light Photodetector Based on Asymmetric Au/CsPbBr3/SmB6 Junction

Abstract

As a typical all-inorganic perovskite, CsPbBr3 has strong visible-light absorption, large carrier mobility and long carrier diffusion length, suggesting it has potential applications in visible-light detection. Many attempts have been devoted to fabricating CsPbBr3 photodetectors, but the reported CsPbBr3 photodetectors were found to have higher dark current of (~10-9A) and low responsivity, remaining a challenging issue for all the researchers until now. In this work, an ambient-pressure chemical vapor deposition (APCVD) way was developed to fabricate single crystalline CsPbBr3 microsheets. Based on the energy-band theory, we devised a novel asymmetric device structure, where metallic SmB6 nanobelt and Au film were respectively used as the electrodes of CsPbBr3 microsheet to form Schottky contact. The measurement results show that the asymmetric Au/CsPbBr3/SmB6 photodetector exhibited much better photosensitive performances than pristine CsPbBr3 photodetector. Most of all, The zero-biased Au/CsPbBr3/SmB6 asymmetric photodetector was found to exhibit a large external quantum efficiency (EQE) of 44.5%, a high detectivity up to 3.38×1010 Jones and a large responsivity (0.184 A/W), overwhelming many other two-dimensional (2D) photodetectors with nice photoresponse behaviors. The excellent visible-light detection performances of the asymmetric photodetector should be attributed to the high separation efficiency of the photogenerated electron-hole pairs at interface built-in field. Our research may pave a new path for fabricating advanced self-powered photodetector device based on 2D materials. Keywords：CsPbBr3 microsheet, ambient-pressure chemical vapor deposition (APCVD), SmB6 nanobelt, asymmetric device, self-powered visible-light detection