Coal-based carbon quantum dots-sensitized TiO2 NRs/PTTh heterostructure for self-powered UV detection

Abstract

In recent years, TiO2-based UV photodetectors (UVPDs) have gained widespread attention owing to their abundant raw materials and low synthesis cost. However, the low responsivity, slow response speed and high-power consumption limit the application of these UVPDs. In this study, p-n heterojunction self-powered UVPDs consisting of n-type coal-based carbon quantum dot-sensitized TiO2 nanorod arrays (TiO2 NRs:C-CQDs) and p-type poly(2, 2′:5′, 2′'-trithiophene) (PTTh) are reported. The structure, morphology and photoresponse properties of the TiO2 NRs:C-CQDs/PTTh heterojunctions are methodically investigated. These results indicate that the sensitization of C-CQDs has a significant impact on the electrical and optical properties of p-n heterojunction UVPDs. The performance study results of UVPDs at different optical power densities show that the device is able to accurately detect UV light of specific wavelengths, and the device achieved a maximum responsivity (R) (1.45 mA/cm2) and a high detectivity (D*) (4.94 × 1010 Jones) when the light intensity is 0.35 mW/cm2, while the rise and fall times shortened to 91.2 ms and 3.19 ms, respectively.These indicate that TiO2 NRs:C-CQDs/PTTh achieves the high performance self-powered UV light detection. This work offers theoretical support and technical route for TiO2 based self-powered UVPDs.