Large-Area, Flexible Broadband Photodetector Based on ZnS-MoS2 Hybrid on Paper Substrate

摘要

Flexible broadband photodetectors based on 2D MoS2 have gained significant attention due to their superior light absorption and increased light sensitivity. However, pristine MoS2 has absorption only in visible and near IR spectrum. This paper reports a paper-based broadband photodetector having ZnS-MoS2 hybrids as active sensing material fabricated using a simple, cost effective two-step hydrothermal method wherein trilayer MoS2 is grown on cellulose paper followed by the growth of ZnS on MoS2. Optimization in terms of process parameters is done to yield uniform trilayer MoS2 on cellulose paper. UV sensing property of ZnS and broadband absorption of MoS2 in visible and IR, broadens the range from UV to near IR. ZnS plays the dual role for absorption in UV and in the generation of local electric fields, thereby increasing the sensitivity of the sensor. The fabricated photodetector exhibits a higher responsivity toward the visible light when compared to UV and IR light. Detailed studies in terms of energy band diagram are presented to understand the charge transport mechanism. This represents the first demonstration of a paper-based flexible broadband photodetector with excellent photoresponsivity and high bending capability that can be used for wearable electronics, flexible security, and surveillance systems, etc.