Hybrid Flexible Thermoelectric Temperature Sensors for Early Warning

Abstract High‐sensitivity thermoresponsive materials are pivotal in intelligent temperature sensing for early warning, particularly when main power fails. Thermoelectric (TE) materials are advantageous for such scenario‐based application, yet those with suitable flexibility, sensitivity and robustness for multifunctional sensing remain challenging due to intrinsic brittleness of pristine inorganic TE materials. Here, a robust temperature sensor based on a Bi 2 Se 3 TE film in situ synthesized with PEDOT:PSS (P@Bi 2 Se 3 ) is developed. This subtle optimization delivers substantial improvement to traditional TE films, with a power factor of 154.7 µW mK −2 at 440 K (three times that of pristine Bi 2 Se 3 ), the highest among reported flexible Bi 2 Se 3 /organic TE films. In addition, the film shows excellent flexibility and stability, with barely 6% conductivity loss after 2000 bendings and 29% stability improvement over pristine Bi 2 Se 3 films. A sensor assembled with this TE film demonstrates outstanding sensitivity and response at 94% efficiency within 1 s. Beyond thermal sensing, the film demonstrates great energy storage potential shown by a Zn//P@Bi 2 Se 3 battery with zero capacity decay after 200 cycles. This facilely prepared hybrid TE film integrating efficient thermoelectric conversion, flexibility and energy storage shows full‐scale advantages over its inorganic analogue, providing solutions for intelligent temperature monitoring in medical assistance and battery safety.