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 TiO₂ electrodes. The first topic is on the surface modification of TiO₂ nano-particles, which is associated with electron traps on the surface of TiO₂ nano-particles. The surface is modified with dye molecules under pressurized CO₂ atmosphere to increase the surface coverage of TiO₂ 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 TiO₂ 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 I₂ molecules with electrons trapped on the TiO₂ surfaces. Selective staining for tandem cells is proposed. The second topic is on the contact between a SnO₂/F transparent conductive layer (TCL) and nano-particles. Polishing the TCL surfaces with silica nano-particles increases the contact, resulting in Jsc increases