A broadband self-powered and stable photothermoelectric detector based on Ag<sub>2</sub>Se/MWCNTs composite fabricated via screen printing

Photothermoelectric (PTE) detectors hold immense potential for converting incident light signals into electrical signals, finding applications in sensing, astronomy, night vision, and communication. However, their widespread adoption is hindered by issues such as slow response times, low responsivity, and poor stability. In this study, a high-performance self-powered PTE detector based on the Ag<sub>2</sub>Se nanorods (NRs) and multi-walled carbon nanotubes (MWCNTs) is reported for the first time. The findings reveal that the electrical conductivity of the film increases with the addition of MWCNTs, albeit at the expense of the Seebeck coefficient. Notably, the film containing 0.5 wt% MWCNTs exhibited a superior power factor (303.22 μW·m<sup>-1</sup>·K<sup>-2</sup>) at 300 K. Owing to the high PTE performance, the photosensitive properties are characterized in an ultra-broadband range from the violet (405 nm) to infrared (2,500 nm) wavelengths, featuring rapid response time (1.4 s) and substantial output voltage (6.83 mV). Furthermore, the device demonstrated remarkable stability, with only a 3.4% decrease in output voltage after three months of air exposure and negligible changes in thirty cycles. Thus, the proposed device presents a novel strategy for developing PTE detectors characterized by broadband coverage, fast response times, and exceptional stability.