Improvement of visible-near-infrared (NIR) broad spectral photocurrent application of PbSe mesostructures using tuning the morphology and optical properties

PbSe mesostructures were synthesized for the broad spectral photocurrent applications from visible region till NIR region. The morphology and optical properties of PbSe mesostructures, which were synthesized by a co-precipitation method, were tuned by different Se/Pb ratios. X-ray diffraction patterns (XRD) and Raman spectra of all seven samples with Se/Pb = 0.7–1.3 ratios indicated that, the samples had the same phase and structure. Scanning electron microscope (SEM) images showed the morphology of the most samples was cubic that the size of these cubics was changed by different Se/Pb ratio. Ultraviolet-visible-nearinfrared (UV–vis-NIR) spectroscopy results of the samples showed that, PbSe mesostructures were able to absorb visible-NIR broad spectra. According to the optical properties, the samples were used to fabricate the photoresponse devices that worked in the broad spectral from the visible to NIR regions. The samples with Se/Pb < 1 showed higher photocurrent intensity and faster response. Mott-Schottky results showed that, all samples were n-type semiconductors and donor carriers concentration is higher for the samples with Se/Pb < 1 ratio. In addition, this result indicated more positive value for flat band potential (Vfb) of the samples with Se/Pb < 1 ratio. X-ray photoelectron spectroscopy (XPS) results also revealed more positive value for the conduction band energy (ECB) of the sample with Se/Pb < 1 ratio. The obtained results showed that, more positive Vfb and ECB of the samples with Se/Pb < 1, as well as higher donor concentration of these samples were three important factors to obtain a photodetector device with higher photocurrent and faster photoresponse.