Effect of deposition time on microstructure and optoelectronic properties of lead selenide thin films

Lead selenide (PbSe) thin films are promising materials for mid-infrared photodetection owing to their narrow bandgap (0.2-0.4 eV), high carrier mobility, and tunable optoelectronic properties. However, current fabrication processes for PbSe detectors still face challenges in producing large-area, high-performance photosensitive films, which has hindered the commercialization of large-format, high-performance PbSe infrared imaging systems. In the chemical bath deposition (CBD) of PbSe thin films, deposition time is a critical parameter influencing film thickness, crystallinity, grain size, compactness, surface morphology, and stoichiometry. This study systematically investigates the role of deposition time in tailoring the morphology, crystallinity, and photoresponse of CBD-prepared PbSe films. Experimentally, the PbSe film deposited for 4.5 h exhibited a dark resistance of 3.078 MΩ and a photoresponse ratio of 20.4%. In comparison, films deposited for 3 h and 5.5 h showed higher dark resistances of 7.396 MΩ and 6.84 MΩ, respectively. XRD and SEM characterization revealed a U-shaped relationship between deposition time and the optoelectronic properties of the PbSe films. Therefore, systematic optimization of deposition time is a key step toward obtaining high-performance PbSe films. This work provides valuable insights for the application of PbSe materials in infrared detection. Through systematic experiments, the PbSe film deposited for 4.5 h exhibited a dark resistance of 3.078 MΩ and a photoresponse ratio of 20.4%. U-shaped dependency between the deposition time and the optoelectronic properties was revealed via CBD-prepared PbSe films. • 1. Through systematic experiments, the PbSe film deposited for 4.5 h exhibited a dark resistance of 3.078 MΩ and a photoresponse ratio of 20.4%. • 2. U-shaped dependency between the deposition time and the optoelectronic properties was revealed via CBD-prepared PbSe films. • 3. Systematic optimization of the deposition time is therefore one of the key steps to obtaining high-performance PbSe films.