ELECTRON TRANSFER DYNAMICS IN NANOCRYSTALLINE TITANIUM DIOXIDE SOLAR CELLS SENSITIZED WITH RUTHENIUM AND OSMIUM POLYPYRIDYL COMPLEXES

摘要

The electron transfer dynamics in solar cells that utilize Ru(H_2L′)_2(CN)_2, Os(H_2L′)_2(CN)_2, Ru(H_2L′)_2(NCS)_2, and Os(H_2L′)_2(NCS)_2 (H_2L′ is 4,4′-dicarboxylic acid 2,2′-bipyridine) adsorbed onto nanocrystalline titanium dioxide photoelectrodes have been studied using optical spectroscopy. The complexes inject electrons into the semiconductor with rate constants k_2 > 10~9 s~(-1), and charge recombination occurs at open circuit with second-order rate constants k_3 = (6.5*10~(-14) / 1.6*10~(-11)) cm~3 s~(-1). The open circuit charge recombination rates decrease with increasing driving force to the oxidized sensitizer, indicating that charge recombination at open circuit at occurs in the Marcus inverted region.