Enhancement of Solar Cell Efficiency by Using TiO2 Nanostructure Doped Fe2O3 Dye and Effect Concentration of Solvent on Optical Properties
Authors: Hamid Abubakr Mahmoud , Hassan Hassan Wardi , Osman Fatima Ahmed 
Published: September 2019

Solar energy has the greatest potential of all the sources of renewable energy, as only a small amount of this form of energy could be used, especially when other sources (coal, oil or gas) in the country have depleted. A solar cell is a solid electrical device that converts solar energy directly to electricity. Hybrid solar cells based on inorganic and organic compounds are a promising renewable energy source.

Aims: The aim of this study was to prepare a nanostructured thin film of titanium oxide: doped iron oxide for enhancement of solar cell efficiency. In addition to studying the effect doped on optical properties of titanium oxide nanostructure thin film.

Study Design: The spray pyrolysis deposition method used for preparation the nanostructure material.

Place and Duration of Study: This study was conducted in the department of physics and department of materials sciences, Al-neelain university, between January 2016 and January 2019.

Methodology: Thin films of Titanium Oxide (TiO2) doped Iron Oxide (Fe2O3) have been prepared by chemical spray pyrolysis deposition technique. A laboratory designed glass atomizer was used for spraying the aqueous solution. Which has an output nozzle about 1mm then the film was deposited on preheated cleaned glass substrates at the temperature of 400ºC. we used different concentration to study optical parameters. A 1.5 g TiO2 powder of anatase structure doped with 1.5 g of Fe2O3 was mixed with 2 ml of ethanol and stirred using a magnetic stirrer for 30 minutes to form TiO2 paste to obtain the starting solution for deposition and spray time was 10 s and spray interval 2 min was kept constant. The carrier gas (filtered compressed air) was maintained at a pressure of 105 Nm-2, and distance between nozzle and substrate was about 30 cm ± 1 cm. The thickness of the sample was measured using the weighting method and was found to be around 400 nm. Optical transmittance and absorbance were records in the wavelength range of (200-1100) nm using UV-Visible spectrophotometer (Shimadzu Company Japan).

Results: The results obtained showed that the optical band gap decreased from 5.58 eV before doping to (3.9, 3.81, 3.81 and 3.81 eV) after doped for TiO2:Fe2O3 thin films, this result refers to the broadening of secondary levels that product by TiO2: doping to the Fe2O2 thin films. Also, the results showed the variation of refractive index with wavelength for different concentration after doped of TiO2:Fe2O3 films from this figure, it is clear that n decrease with low concentration and increase with high concentration after doped that mean the density is decreased of this films. In addition the extinction coefficient of TiO2:Fe2O3 thin films recorded before doped and with different concentration (1.1, 1.2, 1.5 and 1.6 mol/L) and in the range of (300 – 1200) nm and after doped it observed from that the extinction coefficient, decrease sharply with the increase of wavelength for all prepared films and all the sample after doped is interference between them accept the sample before annealing is far from the other sample.

Conclusion: Based on the results obtained doping of titanium oxide increases the efficiency of TiO2 thin film in DSSC. It also proves that the fabrication of TiO2 thin films by spray pyrolysis deposition method is successful.