Strain modulation assisted enhanced broadband photodetector based on large area, flexible, few layered Graphene-MoS2on cellulose paper

Electronic structure and carrier behavior in semiconductor junctions can be effectively modulated on application of strain. This work represents the first demonstration of large area, flexible, paper based Gr/MoS2 broadband photodetector using low-cost solution processed hydrothermal method and enhancement in photodetection through strain modulation by assembling the device on PDMS. Optimization in terms of process parameters were done to obtain trilayer MoS2 over Gr-cellulose paper. Under strain, potential barrier variation and piezopotential induced in MoS2 leads to 79.41% enhancement in photodetection in the visible region. Piezopotential induced in MoS2 lowers the conduction band energy thereby increasing the effective electric field favoring easy electron-hole separation. The advantage of vertically stacked Gr/MoS2 for photodetector is the utilization of the entire area as a junction where an effective separation of electron-hole pair occurs. Detailed mechanism studies in terms of potential barrier variation in Gr/MoS2 and energy band diagram is presented to understand the proposed phenomena. The present work demonstrates the significance of few layer MoS2 or Gr over Chemical Vapor Deposition (CVD) grown counterparts for strain modulated photosensing. The results provide an excellent approach for fabrication of low-cost heterojunctions for improved optoelectronic performance which can be further extended to similar 2D materials heterojunctions for analog, digital and optoelectronic applications