We fabricate an ultraviolet photodetector based on a blend of poly (N-vinylcarbazole) (PVK) and 2- tert-butylphenyl-5-biphenyl-1, 3, 4-oxadiazole (PBD) using spin coating. The device exhibites a low dark current density of 2.2×10 3 μA/cm 2 at zero bias. The spectral response of the device shows a narrow bandpass characteristic from 300 to 355 nm, and the peak response is 18.6 mA/W located at 334 nm with a bias of –1 V. We also study the performances of photodetectors with different blend layer thicknesses. The largest photocurrent density is obtained with a blend of 90 nm at the same voltage. We fabricate an ultraviolet photodetector based on a blend of poly (N-vinylcarbazole) (PVK) and 2-tert-butylphenyl-5-biphenyl-1, 3,4- oxadiazole (PBD) using spin coating. The spectral response of the device shows a narrow bandpass characteristic from 300 to 355 nm and the peak response is 18.6 mA / W located at 334 nm with a bias of - 1 V. We also study the performances of photodetectors with different blend layer thicknesses. The mass photocurrent density was obtained with a blend of 90 nm at the same voltage.