Dye Sensitized Solar Cells with High Photo-Energy Conversion-Controll of Nano-Particle Surfaces

Some of factors affecting photo-conversion efficiency of dye sensitized solar cells (DSCs) are discussed in terms of TiO
₂
electrodes. The first topic is on the surface modification of TiO
₂
nano-particles, which is associated with electron traps on the surface of TiO
₂
nano-particles. The surface is modified with dye molecules under pressurized CO
₂
atmosphere to increase the surface coverage of TiO
₂
nano-particles with dye molecules. This increases Jsc because of an increase in the amount of dye molecules and a decrease in the amount of trapping sites on TiO
₂
nano-particles. In addition, the decrease in the amount of trap sites increases Voc because decreases in Voc are brought about by the recombination of I
₂
molecules with electrons trapped on the TiO
₂
surfaces. Selective staining for tandem cells is proposed. The second topic is on the contact between a SnO
₂
/F transparent conductive layer (TCL) and nano-particles. Polishing the TCL surfaces with silica nano-particles increases the contact, resulting in Jsc increases