Journal of Materials Research and Technology (Jul 2022)
Effect of Cd doping on the structural, optical, and photovoltaic properties of SnS films
Abstract
This paper reports the fabrication of (0 wt. %, 0.5 wt. %, 1 wt. %, 1.5 wt. %, and 2 wt. %) cadmium-doped tin sulphide (Cd-SnS) thin films using sol-gel technique via green synthesis route. Aloe vera gel is used as a green extract to fast fabricate Cd-SnS films. X-ray diffraction (XRD), UV-Vis spectrophotometer, four-point probe method, and J-V measurements are used to determine the crystallographic structure, optical, electrical, and photovoltaic properties, respectively. Here, the detailed structure properties like crystallite size, dislocation line density, d-spacing, and lattice constants of pure and Cd-SnS films are calculated. XRD confirmed the Cd doping in SnS with an orthorhombic structure. The film of 1.5% Cd-SnS showed good structural properties like large crystallite size (29 nm), small d-spacing (2.82 Å), small dislocation line density (1.18 × 1015 m−2), and lattice constants (a = 11.86 Å, b = 3.92 Å, c = 4.33 Å). Optical parameters like bandgap energy (Eg), extinction coefficient (k), refractive index (n), and dielectric constants (n) are calculated by using a UV-Vis spectrophotometer. Cd doped decreased the Eg of SnS. The low value of Eg (1.40 eV) is observed by 1.5% of Cd doping in SnS. A four-point probe approach is used to evaluate the sheet resistivity of Cd-SnS thin films at ambient temperature. The reduced value of sheet resistivity (1.3 × 104 Ω-cm) is achieved at 1.5% Cd doping. Solar cells of these films are fabricated. The geometry of the Cd-SnS solar cell is glass/FTO/TiO2/SnS/P3HT/Au. The open-circuit voltage (Voc), fill factor (FF), efficiency (η), and short circuit current density (Jsc) of solar cells are determined using a J-V curve. For pure SnS based solar cells, Voc is 0.702 V, Jsc is 2.04 mA cm−2, FF is 0.578, and η is 0.82%. All the factors except Voc are increased by Cd doping. The highest efficiency (1.34%) is obtained using a 1.5% Cd-doped SnS film-based solar cell. This efficiency is 61% higher than pure SnS based solar cells. These cells have a low-cost and long life time because there is no chemical corrosion like dye-sensitized solar cells.
