IMPROVING THE EFFICIENCY OF DYE-SENSITIZED SOLAR CELLS WITH SPRAY-COATED TiO2 ELECTRODE MODIFIED BY CuO, NiO, OR In2O3

Abstract

This research investigated the application of the CuO/TiO2, NiO/TiO2, or In2O3/TiO2 thin film electrode in dye-sensitized solar cells (DSSCs). Second metal oxide and TiO2 sols were synthesized separately via sol-gel methods. The sols were mixed and sprayed onto the fluorine-doped tin oxide glass substrates. The amount of second metal oxide added to TiO2 was varied at 0, 0.1, 0.5, 1.0, and 3.0%wt. The electrode layer was sintered at 400˚C for two hours. The addition of CuO, NiO, and In2O3 produced the photovoltaic efficiency of the cell 4.03±0.58% with 0.1%wt. CuO/TiO2, 5.17±0.07% with 0.5%wt. NiO/TiO2, and 6.21±0.87% with 1.0%wt. In2O3/TiO2, respectively. The DSSCs with 1.0%wt. In2O3/TiO2 electrode coated with N3 dye possessed the highest power conversion efficiency, compared with that of DSSCs with pure TiO2 (3.40±0.62%) electrode coated with the same dye. The DSSCs with single-layered NiO/TiO2 or In2O3/TiO2 electrode had the high value of short-circuit current density (Jsc) and consequently high efficiency, which is due to the larger specific surface area of the electrode available for dye adsorption. Furthermore, the double-layered electrode structure with pure TiO2 as the under-layer and 1.0%wt. In2O3/TiO2 as the over-layer was studied. The cell efficiency was increased from 6.21±0.87% to 7.95±0.40%, compared to the single-layered 1.0%wt. In2O3/TiO2 electrode. This can be attributed to light scattering effect as a result of mismatched particle size in the two layers, which increased the reflection of light back into the cell. The enhancement of light reflection was evident from the result of UV-Visible diffuse reflectance spectroscopy.