WS₂ Nanosheet/Graphene Heterostructures for Paper-Based Flexible Photodetectors

We report a low-cost and green synthesis approach to produce high-performance optoelectronics based on WS2-decorated pencil trace on ordinary cellulose paper. It is noteworthy that the photodetector was prepared via simply nontoxic solution-processed WS2 nanosheets, pencil-drawn graphene conducting films, and biodegradable papers. Portable and flexible electronics based on WS2/graphene show excellent photoresponse in a broad spectral region from visible to near IR because of plasmonic improvement and efficient photoabsorption. Liquid-phase-exfoliated atomically thin WS2 nanosheets were decorated on a conducting film of pencil trace using the large area electrophoretic deposition technique. The photodetector based on the WS2/graphene heterostructure shows excellent temporal photoresponse with a responsivity of 0.439 A/W, a detectivity of 1.41 × 1010 Jones, and an external quantum efficiency of 81.39%. The high-performance photodetector shows piezoresistive modulation in electric transport. The device response was investigated up to 500 bending cycles. Finally, the present finding advocates the great development over previously reported nonbiodegradable and small-area optoelectronic devices.