A self-powered ultraviolet photodetector based on TiO2 nanoarrays and poly(3,4-ethylenedioxyselenophene) with the enhanced performance by pyro-phototronic effect

Abstract

Pyro-phototronic effect plays an important role in improving the photodetection performance of ultraviolet (UV) photodetectors (PDs). Here, a novel pyro-phototronic effect between TiO2 nanoarrays (TiO2 NRs) and the conducting polymer poly(3,4-ethylenedioxy selenophene) (PEDOS) is applied to fabricate a self-powered UV PD with the enhanced photodetection ability. The self-powered p-n heterojunction UV PD is fabricated by a face-to-face hybrid of acid (HCl and H2SO4)-treated TiO2 NRs with PEDOS. Interestingly, a pyro-phototronic effect is found between TiO2 NRs/FTO and PEDOS/FTO, and the acid treatment of TiO2 NRs can dramatically enhance the pyro-phototronic effect. H2SO4 treatment can improve the p-n heterojunction, while HCl treatment can increase carrier concentration due to the introduction of surface oxygen vacancies on the surface of TiO2 NRs. Under UV light illumination and 0 bias voltage, the rise time (Trise) and fall time (Tfall) of UV PD from the face-to-face hybrid of PEDOS/FTO with TiO2(HCl)/FTO are 0.080 s and 0.079 s, while the responsivity (R) and detectivity (D*) are 58.706 mA/W and 3.627 × 1011 Jones, respectively. The face-to-face fabrication of UV PDs and the matching of the energy levels between PEDOS and TiO2 NRs cause the pyro-phototronic effect due to temperature change and pyroelectric effect of TiO2 NRs under the UV light illumination. This work gives a new idea to generate pyro-phototronic effect between TiO2 NRs and conducting polymers for application in UV PDs field.