Staggered band offset induced high performance opto-electronic devices: Atomically thin vertically stacked GaSe-SnS2 van der Waals p-n heterostructures

Atomically thin vertically stacked 2D vdW heterostructures have recently emerged as a new kind of device with intriguing novel phenomena for both academic and industrial interests. However, the lack of p-type materials remains a challenging issue to create useful devices for the realization of practical applications. Here, we demonstrate the first vertically stacked few-layered p-type GaSe and n-type SnS2 vdW heterostructure for high-performance optoelectronic applications. It is found that the phototransistors based on a few-layered GaSe/SnS2 p-n junction show superior performance with the responsivity, EQE and specific detectivity as high as similar to 35 AW(-1), 62%, and 8.2 x 10(13) J, respectively, which exceed all the reported values derived from 2D materials. Also, the GaSe/SnS2 p-n junction can serve as a photovoltaic cell with a high power conversion efficiency of about similar to 2.84%. Moreover, the heterostructures can be deposited on flexible PET substrates with excellent performance. Through a detailed study, the underlying mechanism responsible for the high performance can be attributed to the unique type II band alignment and excellent quality of the interface. The heterojunctions presented in this work demonstrate a new illustration for the stacking of 2D materials, which is very useful for the development of next-generation novel optoelectronic devices.