Ultrasensitive photodetector based on 2D WS<sub>2</sub>/AgInGaS quantum dots heterojunction with interfacial charge transfer
Xusheng Wang, Dan‐Ni Yan, Cheng Zhu, Yiping Feng, Tingting Guo, Runmeng Jia, Kairui Qu, Linyun Li, Tong Zhao, Yunhai Xiong, Ahmad Farhan, Yuhai Lin, Linxiang Wu, Yuhui Dong, Shengli Zhang, Xiang Chen, Xiufeng Song
Abstract
Abstract Tungsten disulfide (WS 2 ), as a typical member of transition metal chalcogenides (TMDs), has attracted extensive research interest in optoelectronics, especially photodetectors. However, the performance of photodetectors based on monolayer WS 2 is restricted to weak light absorption. Here, AgInGaS quantum dots (AIGS-QDs) with a large absorption coefficient and high quantum efficiency are integrated onto WS 2 atomic layers to achieve excellent photoelectric performance. Notably, the observed photoluminescence (PL) quenching and the reduction of the decay time of PL in the WS 2 /AIGS-QDs heterojunction confirm the interfacial charge transfer from AIGS-QDs to WS 2 layer. The results show that type II energy band arrangement leads to the efficient separation of photoexcited carriers at the interface between WS 2 and AIGS-QDs. This WS 2 /AIGS-QDs photodetector achieves an ultrahigh responsivity ( R ) of 3.3 × 10 3 A W −1 , an external quantum efficiency (EQE) of 7.8 × 10 6 % and a detectivity ( D *) of 1.3 × 10 13 Jones. Our work provides promising potential for future high-performance monolayer TMD-based photodetectors.