Synthesis of a hemicyanine dye bearing two carboxylic groups and its use as a photosensitizer in dye-sensitized photoelectrochemical cells

Abstract

Two hemicyanine (aminostilbazium) dyes, one bearing two carboxylic groups while the other being its ester analogue, were synthesized for use as photosensitizers in dye-sensitized photoelectrochemical cells (DSPEC). Only the dye with carboxylic groups is covalently attached on mesoporous TiO2 films. The ester analogue, however, is physically adsorbed and it is easily washed off by several solvents. DSPECs of the Graetzel type, made of mesoporous TiO2 films (in our case, synthesized through the reverse-micellar route), of the aminostilbazium. bicarboxylate photosensitizer and of a I-/I-3(-)/propylenecarbonate electrolyte were tested and were found to yield more than 45% maximum photon to electron conversion efficiency and 0.72% overall photovoltaic efficiency. The cells yielded a linear response within a wide range of illumination intensities