Polypyrrole Film Deposited-TiO2 Nanorod Arrays for High Performance Ultraviolet Photodetectors

TiO2-based ultraviolet photodetectors have drawn great attention and are intensively explored. However, the construction of TiO2-based nanocomposites with excellent ultraviolet responses remains challenging. Herein, a TiO2 nanorod array was successfully prepared on fluorine-doped tin oxide (FTO) conductive glass by a one-step hydrothermal method. Then, polypyrrole (PPy)-TiO2 nanorod array composites were designed via subsequent in situ oxidative polymerization. The morphologies, structures, and photocurrent responses of the nanocomposites were systematically investigated. The results demonstrated that polypyrrole-TiO2 exhibited a stronger photocurrent response than pure TiO2 due to the p-n junction formed between n-type TiO2 nanorod arrays and p-type polypyrrole. The PPy-TiO2 composite obtained by deposition three times had the best photoelectric properties, exhibiting good performance with a sensitivity of 41.7 and responsivity of 3.5 × 10−3 A/W. Finally, the mechanism of the photoelectrical response of PPy-TiO2 composites was discussed, guiding the design of high-performance TiO2-based ultraviolet photodetectors.