Perspectives on photodetectors based on selenides and their van der Waals heterojunctions

Two-dimensional layered selenides have attracted intense attention in recent years because of their unique structures and physical properties. Many high-performance electrical and optoelectrical devices based on selenides and their heterostructures have been extensively investigated, and photodetectors have been a particular area of attention. Here, we provide a systematic summary of our recent research progress in selenide-based photodetectors. Three different strategies are introduced and discussed, specifically the use bottom metal contacts, graphene contacts, and bandgap engineering-based vertical van der Waals heterostructures. These approaches are effective for improving the performance of photodetectors based on selenides and their heterostructures. Conclusions are given, and several approaches are proposed for further development of selenide-based optoelectrical devices.