Flexible Bi 2 Te 3 Photothermoelectric Position‐Sensitive Detector

ABSTRACT There is an increasing demand on flexible or wearable position‐sensitive detectors (PSDs) for high‐precision positioning in robots or drones driven by artificial vision. Inherited from conventional materials, e.g., ultrathin Si or multilayer heterojunctions, existing flexible PSDs still suffer from narrow spectral response, poor long‐term stability, and complicated fabrication process. Here we introduce the photothermoelectric effect from thermoelectric Bi 2 Te 3 to create a new type of flexible photothermoelectric PSDs. Such devices can reach a maximum responsivity of 423.2 mV W −1 at room temperature with 43.55 ms response time. Unlike lateral photovoltaic effect based counterparts, our flexible PSDs rely on a single thermoelectric material without heterojunctions or p‐n junctions, enabling position identification and two‐dimensional spot trajectory tracking from visible to near‐infrared (1550 nm). We also developed a theoretical model for the lateral photothermoelectric effect that quantitatively relates the light‐induced temperature field and thermoelectric voltage to the spot position, matching experimental data well over the full position range. The device output remains stable after 1000 bending cycles. This work thus offers an assessable, cost‐effective, and robust route to flexible position‐sensitive photodetectors with broad spectral response in automation of artificial visions smart robotics or drones.