On the photoresponse regulations by deep-level traps in CsPbBr3 single crystal photodetectors

Abstract

The all-inorganic halide perovskite CsPbBr3 has attracted significant attention owing to its excellent opto-electronic properties. However, deep-level traps within the material are significant for the properties of CsPbBr3 based opto-electronic devices. In this study, the effects of deep-level traps on the photoresponse characteristics of CsPbBr3 photodetectors were thoroughly studied. By tailoring the illumination combinations where 532 nm light emitting diode (LED) illumination corresponds to the band-to-band excitation of photo-carriers and 648 nm LED illumination corresponds to sub-band excitation by the deep-level traps, it is proven that the device photoresponse performance is improved by the existence of deep-level traps. The photoresponsivity was enhanced by ∼63.64% (from 0.44 to 0.72 A W−1) under 3.18 μW cm−2 532 nm LED illumination. The rise/fall time was reduced by 21.95% (from 20.5 to 16.0 ms)/25.47% (from 21.2 to 15.8 ms). The underlying physical mechanisms of deep level trap-induced modulations on the photoresponse performance of the CsPbBr3 photodetector were revealed and discussed. By further systematic simulation of the effects of material properties on the photoresponse regulation, it was concluded that a shorter carrier lifetime, higher carrier mobility, higher trap concentration, and deeper trap level could improve the photoresponse of the CsPbBr3 photodetector. This study aims to clarify the physical relation between material properties and device performance and provide guidance for high-performance CsPbBr3 photodetector design.