| 초록 |
Dye-sensitized solar cell has attracted much attention thanks to unique characteristics of transparency and various colors as well as low-cost. Dye-sensitized solar cell is composed of a dye-adsorbed nanocrystalline TiO2 film, redox electrolyte and metallic film. There are several factors affecting photovoltaic performances. We report here how the structural design and interfacial nano-engineering improve solar-to-electrical energy conversion efficiency, associated with light confinement and suppression of recombination. For structural design, effect of scattering particle size on light scattering efficiency has been investigated with a TCO/semitransparent nano-TiO2 layer (underlayer)/scattering layer (overlayer) structure, where two different rutile TiO2 particles of 0.3 µm (G1) and 0.5 µm (G2) were used for a scattering overlayer and 20-nm anatase TiO2 particle for underlayer. It is found significant improvement and strong size-dependence upon deposition of scattering overlayer on the relatively thinner TiO2 underlayer film, which is associated with the quantity and wavelength of transmitted light and the difference in reflectivity of G1 and G2 scattering particles. For interfacial nano-engineering study, we have investigated the effect of blocking layer deposited chemically on TCO. Overall conversion efficiency increases with increasing the precursor concentration and reaches maximum at 0.15 M. Electrochemical impedance spectroscopy study confirms that blocking layer at TCO is found to play an important role in protection of back electron transfer from TCO to electrolyte. The best efficiency of 11% using optimal blocking layer and light scattering conditions has been achieved under AM 1.5G one sun light intensity. |
