Dual Mechanism WS2‐WSe2 Lateral Monolayer Heterojunction Photodetector and Its Photoresponse Enhancement by Hybridizing with CsPbBr3 QDs

Abstract Monolayer 2D lateral heterostructures with high interface qualities and well‐defined structures are particularly promising in novel electronic and optoelectronic applications. However, the photoelectric responses are still very low, and the working and modulating mechanisms urgently need exploration. Here, a lateral monolayer heterojunction of WS2‐WSe2 is successfully prepared with an atomically sharp interface and a band alignment of type‐II structure. Intriguingly, this heterojunction photodetector (PD) achieves outstanding characteristics of photocurrent generation in both photovoltaic and photoconductive modes with responsivities (Rs) of 60.2/3.0 A W−1, detectivities (D*s) of 1.81/0.98 × 1012 Jones, and response times of 32.2/28.5 and 39.5/32.1 ms, respectively. Moreover, all‐inorganic CsPbBr3 quantum dots are introduced to substantially promote the photoelectric responses. Because of the favorable band alignment and large absorption of the CsPbBr3, and efficient carrier transfer, the Rs and D*s are substantially improved to 1307/141.3 A W−1 and 1.16/2.94 × 1013 Jones, respectively, with fantastic external quantum efficiencies of 3.59/0.388 × 105% and also shortened response times of 12.5/13.2 and 17.4/15.8 ms. In addition, the ambient stability is remarkably enhanced. This study demonstrates that the combination of 2D lateral heterojunction with all‐inorganic perovskite may bring up promising opportunities for developing high‐performance PDs.