A UV photodetector was fabricated by sandwich the ZnO QDs-graphene composite in conductive polymers. All the chemicals were purchased from Sigma-Aldrich and used without further purification. First, a thin layer of N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,(1′-biphenyl)-4,4′-diamine (NPD) with thickness around 50 nm was deposited onto pre-cleaned ITO glass substrates through spin coating and then annealed in air at 120 C for 10 min. The NPD act as a hole transport/electron blocking layer.