ZnO Spin-Coating of TiO<sub>2</sub> Photo-Electrodes to Enhance the Efficiency of Associated Dye-Sensitized Solar Cells
- 1 Department of Physics, Taif University, Taif, KSA
- 2 Department of Physics, Taif University, Taif, KSA
- 3 Department of Physics, Taif University, Taif, KSA
- 4 Department of Chemistry, Taif University, Taif, KSA
Abstract
Dye-sensitized solar cells (DSSCs) with ZnO spin-coated TiO 2 photo-electrodes are compared to DSSC with a bare TiO 2 photo-electrode. It is demonstrated that the deposited ZnO of controlled amount, by varying the precursor concentration in the coating sol, can indeed enhance the performance of the DSSC. The measured power conversion efficiency shows a maximum around the precursor concentration 0.1 M and falls down sharply to 0% beyond this point. The results are interpreted on the basis of two competing factors: At ZnO concentrations less than 0.1 M, the formation of an energy barrier increases the photocurrent by reducing the rate of interfacial back-recombination. At ZnO concentrations greater than 0.1 M, the screening of the TiO 2 film by thicker ZnO layers decreases the photocurrent through the reduction of TiO 2 dye-adsorption efficiency.
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