The Structural and Optical Band Gap Energy Evaluation of TiO₂-Fe₂O₃ Composite

Solar cells, one of which is Dye Sensitizer Solar Cell (DSSC), are promising alternative energy in the 2000s. Compared to many other energy sources, solar cell does not emit waste (clean energy). An important component that generates electricity in DSSC is photoanode. TiO₂, the most widely used materials as photoanodes in the current era, is widely used photoanode although the energy gap of the TiO₂ band is quite large (3.43 eV). This study aims to reduce the energy gap of TiO₂ band by forming composites with Fe₂O₃. Various compositions of TiO₂ and Fe₂O₃ fine powders mixtures were dispersed in methanol and stirred until homogeneous in order to synthesize the photoanode. The methanol was then evaporated to obtain a dried mixture of solids, followed by calcination to form composites. The resulted composites were characterized by XRD and Diffuse Reflectance UV-Vis Spectrophotometer. XRD analysis results showed that the composites are composed of TiO₂ and Fe₂O₃ mixtures. Diffuse Reflectance UV-Vis analysis results showed that there was a change in bandgap energy due to the mixing of TiO₂ with Fe₂O₃. The lowest band gap energy is 2.67 eV at 1: 4 ratios. The smallest and largest refractive index values calculated by the Ravindra relation are 2.0725 and 2.4286, respectively. The refractive index value is the reversely proportional of the band gap energy value, the greater the band gap energy, the smaller the refractive index value.