Synthesis and Characterization of Cobalt-doped Titanium Dioxide Thin Films as Solar Cell Components using UV-SEM Analysis

Abstract

Research has been carried out in the form of the synthesis and characterization of thin films of titanium dioxide with the addition of cobalt doping. The purpose of this research was to synthesize and characterize thin films related to optical properties, morphological shapes, and components of thin film compounds that are good for use as basic materials for the development of nanoparticle technology in the form of solar cells. The research was carried out in two stages, namely synthesis such as preparation of glass substrates, preparation of sol-gel solutions, deposition of solutions onto glass substrates, and heating of TiO₂:Co thin film samples. The next stage is the thin film characterization test, where the optical properties of the thin film, such as absorbance, transmittance, gap energy, and activation energy, are measured using a UV-vis spectrophotometer, while morphological data and components of the thin layer compounds are measured using a Scanning Electron Microscope-Energy Dispersive X-rays (SEM-EDX). Based on data analysis and discussion, it was found that the optical properties, such as the transmittance value of the thin film, experienced the lowest point at a wavelength of 250–280 nm with a maximum percentage value of 62.14 to 78.85%. The greater the doping concentration, the lower the transmittance value. This condition is inversely proportional to the absorbance value of the maximum TiO₂:Co thin film, which is in the region with a wavelength of 280–300 nm and a value of 5.70–6.31. The greater the doping concentration, the greater the absorbance value. The energy bandgap values of TiO₂:Co thin films for doping concentrations (0, 5, 10, 15, 20)% were 3.44; 3.39; 3.38; 3.32;  3.22 eV for the direct energy bandgap and 3.86; 3.85; 3.84; 3.85; 3.82 eV for the indirect energy gap. The activation energy of the TiO₂:Co thin film decreased from 2.86 to 2.26 eV. As for the morphological data of the TiO₂:Co thin film, it was found that the greater the concentration of doping, the layer was deposited evenly, finely, and homogeneously. Regarding the data on the components of the thin layer compounds, it was found that the percentage of TiO₂ content was in the range of 64.48–95.94%, while for Co, it was in the range of 0.00–19.21%.