Negative and Positive Bipolar Photoresponse of CsPbBr ₃ /MoSe ₂ Heterostructure

ABSTRACT It is relatively mature to construct positive photoresponse devices nowadays, and there are also a variety of construction strategies for the novel negative photoresponse devices. However, this unipolar photoresponse photodetectors limit their applications in the field of optoelectronics, such as optical logic gates. In this work, we report a CsPbBr 3 /MoSe 2 semiconductor heterojunction photodetector with negative and positive bipolar photoresponse to different visible light bands. With the help of high transparency above 550 nm and the interfacial defects of co‐evaporated CsPbBr 3 , the type‐I CsPbBr 3 /MoSe 2 semiconductive heterostructure shows a negative photoresponse from 340 to 520 nm, with a responsivity of −2.15 A W −1 at 340 nm, and a positive photoresponse above 550 nm, with a responsivity of 19.69 A W −1 at 580 nm, and its application potentials in optical logic device based on the balanced ternary system has been demonstrated. The bipolar photoresponse designed in this work cleverly makes the usages of the optical transparency and defects of CsPbBr 3 perovskite material, the type‐I heterostructure benefiting the exciton recombination, and the two‐dimensional MoSe 2 serving as a broad band carrier transport layer, which opens up a new strategy for designing the bipolar photoresponse devices, revealing application potentials in the logic ternary system.