Self-Biased High-Responsivity Photodetector Based on a Bi₂SeTe₂ Topological Insulator

Topological insulators show promise for high-performance optoelectronic applications due to their nonlinear optical properties, broad spectral absorption, ultrafast response to optical excitation, and excellent thermoelectric properties. Here, we introduce a self-biased photodetector based on the topological insulator Bi₂SeTe₂, driven by the photothermoelectric effect. Operating without external bias, the photodetector delivers a competitive visible-range photoresponse reaching responsivity of ≈27 mA/W and detectivity of ≈2 × 10⁹ Jones at 458 nm. Comparable to individual topological insulators as well as topological insulator-based heterojunctions, this underscores Bi₂SeTe₂’s potential, especially in scenarios where external power sources cannot be used. Its self-biased nature eliminates the need for an external bias, making it an ideal material for low-power and remote-sensing applications.