FeS quantum dots: preparation, structure and optical properties

Transition metal chalcogenides (TMCs) have wide-ranging applications in nanoelectronics and optoelectronics due to their unique energy band structure and excellent properties. Iron(Ⅱ) sulfide quantum dots (FeS QDs) are environmentally friendly semiconductor material and exhibit excellent near-infrared properties because of their narrow bandgap, which is essential for infrared detectors. In this paper, FeS QDs were prepared by liquid phase ultrasonic exfoliation and the solution of FeS QDs was spin-coated on a quartz substrate to form a film. The morphology, structural and optical properties of FeS QDs solutions and films were studied. FeS QDs demonstrated good dispersion with average particle size and height of approximately 11.7 and 10.4 nm, respectively. The calculated average particle size of FeS QDs was 12.7 nm using the Debye-Scherrer formula, which is in good agreement with the TEM characterization. The ultraviolet-visible-near infrared (UV-Vis-NIR) characterization of the FeS QDs solutions and films exhibited obvious absorption in the ultraviolet to near-infrared wavelength band, and the absorption was stable in the near-infrared wavelength band. The photoluminescence (PL) characterization of the FeS QDs solutions and films revealed luminescence properties in the near-infrared wavelength band, and the peak position appeared to be red-shifted with an increase in excitation wavelength, which suggests excitation wavelength-dependent luminescence properties. The FeS QDs exhibit good infrared characteristics and can potentially be used in infrared photovoltaic and photodetector.