Structural, optical, dielectric and photovoltaic properties of Sn doped CdS films prepared with green synthesis route

Abstract

Energy harvesting from renewable energy sources is one of the burning topics in today's research community. Solar cells are emerging as a potential candidate to harvest solar energy into electrical one. Here, we tested a series of pure and Sn-doped CdS as photoabsorbers in solar cells prepared by the sol-gel technique via the green synthesis route. The formation of a hexagonal wurtzite crystal structure of pure and Sn-doped CdS is confirmed using X-ray diffraction analysis. Doping of Sn caused a slight change in lattice parameters, crystallite size, d-spacing, and dislocation line density. UV–vis measurement revealed the direct bandgap nature of the material with bandgap value of 2.50 eV which reduced the 2.20 eV upon 3% Sn doping. Optical parameters, including extinction coefficient and refractive index, are measured. The film prepared with 3% of Sn doping has a high refractive index, i.e., 2.56. In addition, the imaginary and real parts of the dielectric constant are measured in the frequency range of 20Hz to 20 MHz, which exposed the presence of different relaxation phenomena in this composition. The solar cell prepared with 3% of Sn doping has a high value of current density (3.57 mA-cm−2), open circuit voltage (0.49 V), fill factor (0.654) and efficiency (1.14%). This solar cell is a stable cell due to the absence of liquid corrosion like in dye-sensitized solar cells.