Self-powered and broadband response photothermoelectric detector based on Bi2Te3 nanowires and carbon nanotubes sandwich structure

Abstract

The broadband photodetectors recently attract widespread interest since the detector with multiple band response is highly desired. The traditional photodetector is inferior than thermal detector in meeting such requirement because the band gap transition dependent on sufficient photon energy, and the long wavelength region with weak energy may beyond detection. Here, bismuth telluride (Bi₂Te₃) nanowires (∼21.5 nm diameter, aspect ratios up to 80) are embedded between carbon nanotube (CNT) layers to construct a sandwich-structured detector for broadband detection from ultraviolet to near-infrared. A temperature gradient induced by localized photothermal conversion drives directional flow of charge carriers to generate electric potential via Seebeck effect, enabling self-powered operation of the detector without external power sources. The I-V curves and position dependent photovoltage of the detector based on CNT/Bi₂Te₃/CNT film confirm that the mechanism of signal generation stems from photothermoelectric effect. The CNT layers serve as both an efficient photothermal conversion layer and charge transport channel, while simultaneously forming an energy filtering effect with Bi₂Te₃ to improve the Seebeck coefficient. As a result, the CNT/Bi₂Te₃/CNT detector achieves efficient wideband detection across 380 nm–1550 nm, with a maximum specific detectivity reaches 1.27 × 10⁹ cm Hz^1/2 W⁻¹, representing a ∼115 % enhancement over a pure CNT detector. This work offers significant reference for the preparation of nanowire and the design of high-performance photothermoelectric detector.