Flexible Ultraviolet and Ambient Light Sensor Based on a Nanomaterial Network Fabricated Using Selective and Localized Wet Chemical Reactions

We report ZnO nanowire- and TiO₂ nanotube-based light sensors on flexible polymer substrates fabricated by localized hydrothermal synthesis and liquid phase deposition (LPD). This method realized simple and cost-effective in situ synthesis and integration of one-dimensional ZnO and TiO₂ nanomaterials. The fabricated sensor devices with ZnO nanowires and TiO₂ nanotubes show very high sensitivity and quick response to the ultraviolet (UV) and ambient light, respectively. In addition, our direct synthesis and integration method result in mechanical robustness under external loading such as static and cyclic bending because of the strong bonding between the nanomaterial and the electrode. By controlling the reaction time of the LPD process, the Ti/Zn ratio could be simply modulated and the spectral sensitivity to the light in the UV to visible range could be controlled.