Tuning band gap, structural and optical properties of tin selenide nanoparticles by alkali metal doping

Abstract

The layered chalcogenide semiconductor, Tin monoselenide is an extraordinary candidate among chalcogenide materials because of their novel physical and chemical properties and tremendous applications in thermoelectrics, solar cells, energy storage devices, i.e. metal–ion batteries, supercapacitors etc. In this work, we synthesized polycrystalline SnSe by a simple hydrothermal method using sodium borohydride as a reducing agent for the single phase formation of SnSe nanostructures. X–ray diffraction spectroscopy has been done to confirm the orthorhombic structure and single phase formation. Fourier transform infrared characterization has been done to observe the linkage of groups among the precursors and solvents used. Further, Photoluminescence characterization has been done to estimate the band gap values and radiative recombination mechanism of the material. Ultraviolet–Visible (UV–Vis) spectroscopy has been used to study the optical properties of the material. Moreover, extrinsic heteroatom doping of sodium and potassium have been done to form NaxSnx-1Se and KxSnx-1Se respectively, which further decreases the band gap of the host material. The absorbance spectra, percentage of transmittance, extinction coefficient, direct band gap values depend upon photonic interactions and has been determined by UV–Vis spectroscopy. Elemental composition of each sample has been confirmed by EDX spectroscopy. All these properties have made the material a potential candidate for opto–electronic and photovoltaic applications.