Flexible self-powered ultraviolet-visible photodetector based on polyaniline‑titanium dioxide heterostructures: The study of the rearrangement of layers

At the moment, the flexible self-powered photodetectors (PDs) with multi-color detection capability have attracted significant attention due to the adaptability, ease of use and operating without an external power supply. In this paper, Polyaniline/Titanium dioxide (PTP) and Titanium dioxide/Polyaniline (TPP) heterojunctions were deposited on a flexible PET substrate and investigated as ultraviolet (UV) and visible (vis) lights PDs. I-V curves of the PTP and TPP under UV and vis light illuminations have exhibited different contrast ratios, rectification ratios, effective barriers height and reverse saturation currents that imply the capacity of the devices for use as the effective two-color PDs without an external power source. The devices showed different photo-detectivity and response speed under UV and vis illuminations when the PDs layers arrangement changed. Furthermore, the photo-responsivity, response speed and lights detection of the devices under different UV and vis lights power densities were examined in detail through I-t curves at zero bias voltage, and the results confirmed the PTP is a suitable candidate for the self-powered UV-PD, while the TPP is an appropriate volunteer for the self-powered vis-PD.