Synthesis and Characterization of SnS Nanoparticles through a Non-Aqueous Chemical Route for Depositing Photovoltaic Absorber Layers

Abstract

SnS nanocrystals of sub-10 nm in size were synthesized by a room temperature, non-aqueous chemical route in the presence of different amounts of triethanolamine (TEA) used as a complexing agent. The crystallinity, size, morphology, chemical composition and optical properties of the as-prepared SnS nanoparticles were investigated by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Energy-dispersive X-ray spectroscopy (EDS), micro Raman and optical absorption spectroscopy. The XRD analysis and HRTEM investigation of SnS nanoparticles confirmed the presence of crystalline orthorhombic SnS phase. Upon increasing the amount of TEA, the crystallite size of the samples decreased gradually showing evidence of quantum confinement. EDS analysis showed that SnS nanoparticles (NPs) grown in absence of TEA were highly stoichiometric whereas in TEA capped samples, the atomic concentration of S is slightly higher than that of Sn. As-synthesized SnS nanocrystals displayed strong absorption in the visible and near-infrared spectral regions followed by a blue shift of their absorption edge on increasing the TEA concentration. These nanoparticles were used to prepare SnS paste which was deposited on conducting glass substrates to obtain thin films for photovoltaic applications. The crystallinity, morphology, chemical composition and optical properties of annealed SnS films were investigated.