Enhanced performance of ultraviolet photodetector modified by quantum dots with high responsivity and narrow detection region

A high performance photovoltaic ultraviolet photodetector (UVPD) based on Polyvinyl carbazole (PVK)/TiO2 heterojunction with CuInS2/ZnS quantum dots (CIS-Z QDs) doped in PVK layer was fabricated in a simple method with great exhibition of high responsivity (R) and fast response. When the device is in dark, the depleted p-n heterojunction structure will lead to a low dark current density with the value of 0.05 μA/cm2. Because of the different absorbance that the materials have, the detector has a narrow detection wavelength region from 310 nm to 350 nm. Meanwhile, due to the quantum size effect that CIS-Z QDs have, the electric-field intensity of the depletion is enhanced. Besides, the conductivity of the device has also been improved by CIS-Z QDs. Therefore, the photo-generated carrier will be effectively separated and lead to a high R and fast response with the value of 0.19 A/W and 24 m s. The research suggests that after doping CIS-Z QDs, organic/inorganic p-n hybrid heterojunction UVPDs possess the potential to enhance photo detection performance.