Masaki Minami

Triarylamine-Functionalized Ruthenium Dyes for Efficient Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) based on mesoporous nanocrystalline TiO2 films have been attracting intensive interest for scientific and industrial applications because of their high photo-to-electricity conversion efficiency and low production cost . Although numerous sensitizers, including metal-free organic dyes and nonruthenium metal dyes, have been employed, the best energy conversion efficiency of up to 11% was achieved by using ruthenium dyes, such as N3, N719, and the black dye [2] in standard global air mass 1.5 sunlight. To raise further the efficiency of these cells, much effort has been directed toward the development of highly efficient solar cells based on ruthenium dyes. There are several basic requirements guiding the molecular engineering of an efficient sensitizer. The LUMO of the dye must be sufficiently high in energy for efficient charge injection into the TiO2, and the HOMO must be sufficiently low in energy for efficient regeneration of the oxidized dye by the hole-transport material (HTM) . Finally, light excitation should be associated with vectorial electron transfer from the excited dye to the TiO2 conduction band. On the other hand, the triarylamine molecules have aroused great interest for their excellent hole-transport capability , and organic dyes including triarylamine moiety acting as an electron donor exhibit high efficiencies in the conversion of solar energy into electricity .