Photovoltaic–Pyroelectric coupled effect enhanced photo-responsivity of a p-n heterojunction Self-Powered ultraviolet photodetector

TiO 2 -based ultraviolet (UV) photodetectors (PDs) with broadband optical detection range are widely used in commercial and military applications. Nevertheless, the self-powered UV PDs of TiO 2 nanoarrays (NRs) have relatively low response rates and slow response times. Here, a high responsivity self-powered p-n heterojunction UV PD based on TiO 2 NRs: CQDs/FTO and PEDOS/FTO is fabricated by a simple face-to-face assembly process. The pyroelectric effect of TiO 2 NRs is enhanced by sensitizing TiO 2 NRs with CQDs, which would reduce the bandgap value of TiO 2 NR, broaden the range of photoresponse, and reduce recombination of electron-hole. Furthermore, the pyro-phototronic effect of CQDs, the energy level matching from CQDs to PEDOS and the interaction between –OH in CQDs and ethylene oxide groups in PEDOS enhance the performance of the prepared UV PDs. The TiO 2 NRs: CQDs//PEDOS UV PDs achieve a high photo-responsivity and photo-detectivity of 150.95 mA/W and 3.73 × 10 11 Jones at 0 bias (365 nm), respectively, which are better than those at wavelengths of 380 nm. We also found that the photocurrent induced via the pyro-phototronic effect increases with the light power intensity. This work points the way for photovoltaic and photo-induced pyro-phototronic effects to improve the performance of TiO 2 NRs-based UV PDs.