Transparent and flexible ultraviolet photodetectors based on colloidal ZnO quantum dot/graphene nanocomposites formed on poly(ethylene terephthalate) substrates

Abstract

Transparent colloidal ZnO quantum-dot (QD)/graphene nanocomposites were formed on poly(ethylene terephthalate) (PET) substrates. Ultraviolet (UV)-visible absorption spectra showed a shoulder peak around 350 nm corresponding to the absorption of ZnO QDs. Optical transmittance of the ZnO QD/graphene/PET multilayer was approximately 80%. High-resolution transmission electron microscopy images showed that the ZnO QDs were distributed along the circumferences of the surfaces on the graphene layers. Current-voltage and current-time measurements on the UV photodetector after bending at 300 K exhibited the ON/OFF switching states and stability resulting from the light-induced conductivity of the flexible graphene layer.