Carbon Quantum Dots/ZnO Hybrid Nanostructured Thin Films and UV Photodetector Performances

A hybrid platform is engineered: carbon quantum dots (CQDs) seamlessly integrate with Zinc oxide (ZnO) nanostructures, forming the hybrid heterojunction thin films. The ultraviolet (UV)‐visible transmittance spectra of the CQDs/ZnO nanorods (NRs) heterojunction films exhibit the reduced transmittance, attributed to the adsorbed CQDs acting as the light‐scattering centres. X‐ray diffraction study confirms the hexagonal wurtzite structure of ZnO across all films. The X‐ray photoelectron spectra of CQDs/ZnO NRs film reveal that the Zn and O 1s peaks are shifted toward the higher binding energy, suggesting a chemical interaction between the CQDs and ZnO in the hybrid films. The decreased photoluminescence in CQDs‐decorated ZnO films may be due to reduced charge recombination at the heterojunction interface, facilitating significant charge transfer from CQDs to ZnO. The CQDs‐decorated ZnO NRs (CQDs/ZnO NRs film)‐based UV photodetector exhibits the higher current density (693.1 μAcm −2 ) under the UV light exposure (365 nm) of 1 mWcm −2 at 6 V with the responsivity of 545.2 mA/W and external quantum efficiency of 185.2% compared to that of ZnO NRs film‐ (639.3 μAcm −2 , 447.9 mA/W, and 152.1%) and the CQDs/Ni‐doped ZnO NRs film‐ (369.3 μAcm −2 , 354.6 mA/W, and 120.7%) based devices, attributed to the effective charge separation and/or significant energy transfer from CQDs to ZnO NRs.