Growth of Carbon Dot-Decorated ZnO Nanorods on a Graphite-Coated Paper Substrate to Fabricate a Flexible and Self-Powered Schottky Diode for UV Detection

The fabrication of flexible as well as self-powered optoelectronic devices is a growing and challenging area of research. Some scientists have reported the fabrication of either flexible or self-powered photodetectors recently. However, most of the literature studies fail to report the fabrication of self-powered as well as flexible photodetectors. This study reports the fabrication of self-powered, carbon dot (CD)-enhanced, flexible ZnO/graphite heterojunction-based UV detector where cellulose paper has been used as the substrate. A detailed study on the crystallinity and the defects of the ZnO nanorods has been done with appropriate characterizations. The CD-enhanced ZnO/graphite heterojunction showed Schottky characteristics. The Schottky parameters such as the barrier height, ideality factor, and the series resistance have also been calculated using the Cheung–Cheung method. The observed values of barrier height, ideality factor, and the series resistance are 0.74 eV, 3.74, and 503 kΩ, respectively. The transient response at self-powered condition has been demonstrated. The response time and the recovery time at self-powered condition have also been calculated with the help of the transient response, and those values are ∼2 and ∼3.2 s, respectively. The responsivity and the specific detectivity of the fabricated UV detector have been calculated as 9.57 mA/W and 4.27×108 Jones, respectively, at 330 nm wavelength, which is quite comparable with literature-reported values, considering a self-powered photodetector.