Spray-coated Ag2Se thin films for high-performance photothermoelectric detectors

Photothermoelectric (PTE) detectors have the advantages of self-powered, broadband, and cooling-free, which have great potential for application in the fields of security monitoring, fire detection, and military reconnaissance. However, the practical application of PTE detectors still faces problems such as complicated preparation process, limited spectral detection range, and poor reliability. In this work, a spray-coating process is proposed for the fabrication of Ag₂Se-based PTE detectors. Cold pressing is then used to improve the PTE properties of the devices. Self-powered detection was achieved over a broadband range of 405–2500 nm, with an output voltage of 6.83 mV at an optical power density of 100 mW/cm² at 405 nm. The cold-pressed detector maintains a stable response after 3900 s of continuous operation, with the fastest response time of 0.9 s. Further design of the thermopile structure validates its promising applications in contact human temperature monitoring and non-contact human infrared detection. This work provides a new method for the preparation of broadband, self-powered PTE detectors.