Nitrogen-doped carbon quantum dots decorated ZnO nanorods array film for efficient UV photodetector applications

In this study, the ZnO nanorods (ZNRs) array films have been grown by hydrothermal method and decorated with nitrogen-doped carbon quantum dots (N-CQDs). The FESEM and XRD studies show the ZNRs are vertically grown as array and are highly c-axis (002) oriented. The photoluminescence spectra ascertain the absorption of UV light by adsorbed N-CQDs onto the surface of ZNRs and possible energy transfer to ZnO, resulting in the increased narrow band-edge emission (379 nm) of ZNRs array films. The N-CQDs decorated ZNRs array film-based UV photodetector exhibits the highest photocurrent density of 504 mu A/cm2 at 8 V under the UV light (365 nm) illumination of 3 mW/cm2, resulting in the higher device responsivity (142.4 mA/W at 8 V) and external quantum efficiency (48.4% at 8 V) when compared to that of the ZNRs array film (106.6 mA/W and 36.2%) or ZnO seed layer (9.3 mA/W and 3.1%) based devices. These results show that N-CQDs/ZNRs hybrid structure will be very much useful for the fabrication of solution processed efficient UV photodetectors.