Study of Doped Sb2S3 Sensitizer for Third Generation Solar Cell

Abstract

The dye-sensitized solar cell has been investigated as the most promising candidate for photovoltaic applications due to its unique properties, low cost and suitable power conversion for commercial purposes. In this dissertation the thin films of Sb2S3 are synthesized by hydrothermal method with different doping ratios of copper (Cu). The prepared material is further characterized by different techniques. UV-Vis is used to analyze the absorption spectrum of both doped and un-doped materials. The results show that the absorption spectrum have sharp edge close to the band edge which indicates that it has direct band gap. The band gap calculations are 2.01 eV in case of un-doped Sb2S3 and 1.32 eV to 1.45 eV in case of 3% - 5% Cu doping. This variation in band gap calculations can be attributed to change in film thickness and higher concentrations of Cu doping. FTIR is used to analyze the bond vibrations of different groups which are present in Sb2S3 with different Cu-doping ratios. The peaks in FTIR spectra indicate that the peak intensity is increased with 3% cu-doping but decreased with 5% Cu-doping. Raman spectroscopy is used to analyze the different frequency modes present in the material. The peaks at approximately 260cm-1 and 950cm-1 are representing the different symmetric and anti-symmetric Sb-S stretching present in the material. The SEM results show the spherical shapes of un-doped Sb2S3 nanoparticles having average size range 80 nm but in case of 3% Cu doping, the nanoparticles make clusters or bunches with each other which indicate that by doping with different Cu ratios, the structure have been changed. It has been observed that with 5% Cu and above the doping will agglomerate the material which is not feasible for solar cell applications. The maximum energy conversion efficiency is recorded 1.4% with 3% Cu doping having FF of 0.75, Voc of 0.70 V and Jsc of 27 mAcm-2. The efficiencies of un-doped and 5% are recorded as 0.76% and 0.96% with different values of Jsc, Voc and FF. This variation of efficiency can be related to different grain size and chemical composition of material.