Giant Negative Photoresponse in Van Der Waals Graphene/AgBiP 2 Se 6 /Graphene Trilayer Heterostructures.

The positive photoconductive (PPC) effect is a well-established primary detection mechanism employed by photodetectors. In contrast, the negative photoconductive (NPC) effect has not been extensively investigated thus far, and research on the NPC effect is still in its early stage. Herein, a quaternary van der Waals material, AgBiP 2 Se 6 atomic layers, is discovered to achieve a giant NPC effect. Through experimental observations in a Graphene/AgBiP 2 Se 6 / Graphene-based vertical photodetector, we have identified an irreversible conversion from common PPC photoresponse to atypical NPC photoresponse. Notably, this device demonstrates an exceptionally high negative responsivity (R) of 4.9 × 10 5 A/W, surpassing the previous records for NPC photodetectors. Additionally, it exhibits remarkable optoelectronic performances, including an external quantum efficiency (EQE) of 1.3 × 10 8 % and a detectivity (D) of 3.60 × 10 12 Jones. The exceptionally high NPC photoresponse observed in our device can be attributed to the swift suppression of photogenerated free carriers at robust recombination centers (RCs) situated at significant depths, induced by the elevated drain-source voltage bias. The remarkably high NPC photoresponse also positions AgBiP 2 Se 6 as a promising 2D material for multifunctional optoelectronic devices and an excellent platform for systematic exploration of the NPC effect. This article is protected by copyright. All rights reserved.