Enhancing the Detection Sensitivity of PbSe Thin Film TTE Photodetector by Adding Light-Trapping Coatings

PbSe with a promising transverse thermoelectric (TTE) effect has great potential for application in self-powered ultrabroadband photodetection. Here, the detection sensitivity has been remarkably improved by adding graphite coatings with light-trapping structure on the surface of PbSe thin film when it is irradiated by continuous-wave (CW) lasers with wavelengths ranging from the ultraviolet to far infrared. The detection sensitivity Rn of PbSe thin film coated with 15-
$\mu $
m-thick graphite reaches
$415~\mu $
V cm/W under the irradiation of 10.6-
$\mu $
m CW laser, which is nearly five times larger than that of the bare PbSe thin film. The coated graphite, which harvests and converts irradiation into heat, greatly enhances the photothermal conversion efficiency by efficiently using incident light. The enhanced laser absorption results in an increased temperature difference between the top and bottom of the film, significantly improving Rn of the PbSe thin film TTE photodetectors. This work not only offers an effective strategy for enhancing the TTE performance of ultrabroadband photodetector but also promotes their future applications in terms of TTE thermal sensors.