Improved responsivity of MgZnO film ultraviolet photodetectors modified with vertical arrays ZnO nanowires by light trapping effect

Self-powered ultraviolet/visible photodetector based on graphene-oxide via triboelectric nanogenerators performing by finger tapping

Self-sufficient power sources provide a promising application of abundant electronic devices utilized in detection of ambient properties. Recently, triboelectric nanogenerators (TENGs) have been widely investigated to broaden the self-powered systems by converting the ambient mechanical agitations into electrical voltage and current. Graphene oxide (GO), not only for sensing applications but also as a brilliant energy-related nanomaterial, provides a wide range of controllable bandgap energies, as well as facile synthesis route. In this study, GO-based self-powered photodetectors have been fabricated by conflating the photosensitivity and triboelectric characteristics of freestanding GO paper. In this regard, photodetection via TENGs has been investigated in two forms of active and passive circuits for ultraviolet (UV) and visible illumination. The photodetector responsivity upon UV enhanced from 0.011 mA W^-1for conventional GO-photoresistors up to 13.41 mA W^-1by active photodetection setup. Moreover, applying the active-TENG improved the efficiency from 0.25% (in passive TENG) to 4.21%. Our findings demonstrate that active TENGs might enable materials with insignificant optical response to represent considerably higher light-sensitivity by means of synergizing the effect of TENG output changes with opto-electronical properties of desired layers.

High-performance flexible UV photodetector based on self-supporting ZnO nano-networks fabricated by substrate-free chemical vapor deposition

Self-supporting ZnO nano-networks have been demonstrated by a substrate-free chemical vapor deposition process for the application as flexible ultraviolet (UV) photodetector. The device shows a responsivity of ∼300 mA W^-1over a wide wavelength range from 254 to 365 nm and a high UV/visible rejection ratio of more than 10⁴. More interestingly, a short 90%-10% decay time of <0.12 s can be observed in the air atmosphere, and the current can fully recover to its original dark value within 1 s after switching off the light. The quick response speed should be associated with the wire-wire junction barriers and the adsorption/desorption process of oxygen molecules on the oxygen vacancies near the surface of the ZnO. In addition, the photocurrent, the dark current and the response speed of the ZnO nano-networks flexible UV photodetector nearly stay the same under different bending conditions, suggesting the excellent photoelectric stability and repeatability. Such a simple and cheap way for fabricating self-supporting ZnO-based devices has broad application prospects in the fields of flexible and wearable electronic devices.