Flexible photodetector based on cotton coated with reduced graphene oxide and sulfur and nitrogen co-doped graphene quantum dots

Here, we demonstrate a high-performance flexible photodetector based on S and N co-doped graphene quantum dots (S,N-GQDs)-modified reduced graphene oxide (rGO) film for wearable applications. To fabricate the hybrid photodetector, S,N-GQDs are simply sprayed on rGO-coated cotton substrate that is fabricated through a vacuum filtration process. Owing to the synergistic effect of S, N-GQDs and rGO, high responsivity (0.2–1.25 A W−1) and detectivity (3.86 × 1010 J) at a low operating voltage are achieved in the broad spectral range from UV to near infrared. The underlying mechanism is attributed to the separation of photogenerated electrons and holes due to the charge transfer caused by the appropriate band between S,N-GQDs and rGO. Furthermore, the large absorptivity of S,N-GQDs and the excellent conductivity of the rGO also play significant roles. The attributes of flexibility, high detectivity, and sensitivity of our novel flexible photodetector indicate promising potential for future wearable optoelectronic devices.