Three novel hemicyanine derivatives, (E)-N-(4-sulfopropyl)-4-[2-(4- N, N-diethylaminophenyl)-ethenyl]pyridinium (EPS), (E)-N-(4-suMbbutyl)- 4-[2-(4-N, N-diethylaminophenyl)ethenyl]pyridinium (EPS4), and (E)-N-(4- su)fobutyl)-4-[2-(4-N, N-diethylaminophenyl)ethenyl]quinolinium (EQS4) with different length of alkyl chains between the adsorbing group (RSO3-) and the chromophore group, were synthesized and their photophysical and photoelectrochemical properties were studied. Experimental results show that using either three-methylene group or four-methylene group to link the adsorbing group and the chromophore group has little effect on the photoelectrical response of dye, but this difference has great impact on the adsorbance properties of dye on nanocrystalline electrode. EPS, bearing a chain of three-methylene group, has a greater adsorbed molecule amount on nanocrystalline TiO2 film because of small steric hindrance effect compared with EPS4. So EPS-sensitized solar cell generated a higher overall photon to electric conversion efficiency. Compared with EPS4, the photoelectrical response of dye EQS4 was greatly improved when a stronger electron acceptor was introduced. However, samely due to the steric hindrance effect, the adsorption number of EQS4 on mesoporous TiO2 film (2.99 * 1016 molecules ? cm-2) dropped down drastically compared with that of EPS4 (6.26 * 1016), and at last EQS4-sensitized solar cell generated a lower overall photoelectrical conversion yield compared with EPS4.

Key words: TITANIUM DIOXIDE, NANOPHASE MATERIALS, ELECTRODE, hemicyanine, PYRIDINE P, QUINOLINE P, SOLAR CELLS