Application of Nanostructured TiO 2 in UV Photodetectors: A Review.

As a wide-bandgap semiconductor material, titanium dioxide (TiO 2 ), which possesses three crystal polymorphs (i.e., rutile, anatase, and brookite), has gained tremendous attention as a cutting-edge material for application in the environment and energy fields. Based on the strong attractiveness from its advantages such as high stability, excellent photoelectric properties, and low-cost fabrication, the construction of high-performance photodetectors (PDs) based on TiO 2 nanostructures is being extensively developed. An elaborate microtopography and device configuration is the most widely used strategy to achieve efficient TiO 2 -based PDs with high photoelectric performances; however, a deep understanding of all the key parameters that influence the behavior of photon-generated carriers, is also highly required to achieve improved photoelectric performances, as well as their ultimate functional applications. Herein, an in-depth illustration of the electrical and optical properties of TiO 2 nanostructures in addition to the advances in the technological issues such as preparation, microdefects, p-type doping, bandgap engineering, heterojunctions, and functional applications are presented. Finally, a future outlook for TiO 2 -based PDs, particularly that of further functional applications is provided. This work will systematically illustrate the fundamentals of TiO 2 and shed light on the preparation of more efficient TiO 2 nanostructures and heterojunctions for future photoelectric applications.