Down conversion of high energy photons in anatase based TiO2 solar cells

For improving solar efficiencies, down conversion of high-energy photons to visible lights is discussed. The losses due to thermalization of charge carriers generated by the absorption of high-energy photons, can largely be reduced in a solar cell if more than one electron-hole pair can be generated per incident photon. The solar cell consists of dye-sensitized anatase-based TiO2, approximately 30 nm particle size, 6 mum thickness, and 6 x 6 mm(2) active area, Pt counter electrode and I-3(-)/I-2(-) electrolyte Down conversion phosphor LiGdF4:Eu(LGF) located on the front surface of the solar cells. And we measured the photocurrent, current-voltage characteristics, and down-conversion efficiency of the down conversion system.