Reversible Phase-Transition-Enabled Broadband Infrared Photodetection in 1T-TaS2

Broadband infrared photodetectors operating at room temperature are fundamentally limited by the lack of efficient gain mechanisms for weak optical signals. Phase-transition materials provide a promising route for intrinsic signal amplification owing to their extreme sensitivity near critical transition boundaries. However, the strong thermal hysteresis associated with phase transitions often leads to irreversible switching and poor operational stability, limiting their application in photodetection. Here, we demonstrate a reversible phase-transition-enabled infrared photodetector based on few-layer 1T-TaS₂. By integrating the device onto a suspended 200 nm SiN_x membrane and employing a pulsed-bias driving scheme, cumulative Joule heating is suppressed while preserving threshold triggered charge-density-wave phase transition, enabling stable and reversible collective conductivity switching. Operating through phase-transition amplification rather than conventional photoconductive or bolometric mechanisms, the device exhibits broadband response from 0.45 to 10.6 μm, with a maximum responsivity of 3.13 × 10⁴ A/W and a detectivity of 3.8 × 10¹⁰ Jones, along with fast response times (74 μs rise and 17 μs fall) and excellent cycling stability. Furthermore, reliable blackbody detection is achieved for blackbody source temperatures ranging from 773 to 1373 K, highlighting its potential for uncooled infrared photodetection. These results establish reversible phase-transition amplification as an effective strategy for high-sensitivity photodetection and provide a general framework for optoelectronic sensing based on collective electronic phase transitions.