High performance self-powered ultraviolet photodetectors based on P(TTh-co-EDOT) copolymer sensitized TiO2 NRs

A self-powered ultraviolet photodetector (UV PD) effectively utilizes UV energy and has attracted greatly attention due to its no consuming of any external power. In this work, TiO 2 nanoarrays (NRs) were synthesized by a one-step hydrothermal method, which was combined with P(TTh-co-EDOT) to realize a high-performance p-n heterojunction UV PD, and P(TTh-co-EDOT) was evaluated as the photosensitive layers in UV PDs for the first time. Furthermore, the working mechanism for the self-powered of UV PD was discussed in detail based on the energy band theory. Different electrochemical deposition cycles of TTh-co-EDOT on the surface of TiO 2 NRs were applied to form p-n heterojunction for achieving the optimum photoelectric performance. Among them, it was found that the optimum UV PD based on face-to-face fabrication of TiO 2 NRs and P(TTh-co-EDOT) from 3 deposition cycles exhibits an enhancement of photoelectric performance without applying any external voltage. Benefiting from the enhanced built-in electric field of the TiO 2 NRs/P(TTh-co-EDOT) interface, balancing photogenerated carriers and the charge separation and transport in self-power mode, the responsivity and detectivity of TiO 2 NRs/P(TTh-co-EDOT)-3C are 2.252 mA/W and 3.413 × 10 10 Jones, with the rise and fall times are 0.256/0.427 s, which exhibited excellent photoelectric properties and stability. TiO 2 NRs/P(TTh-co-EDOT)-1C has the lowest responsivity (0.0995 mA/W) and detectivity (6.035 × 10 9 Jones) and TiO 2 NRs/P(TTh-co-EDOT)-4C has the longest rise and fall times (0.460/0.451 s). These results suggest that the great potential of the TiO 2 NRs and P(TTh-co-EDOT) for high-performance UV PDs.