Kinetics of electron recombination of dye-sensitized solar cells based on TiO2nanorod arrays sensitized with different dyes

Abstract

The performance and electron recombination kinetics of dye-sensitized solar cells based on TiO₂ films consisting of one-dimensional nanorod arrays (NR-DSSCs) which are sensitized with dyes N719, C218 and D205, respectively, have been studied. It has been found that the best efficiency is obtained with the dye C218 based NR-DSSCs, benefiting from a 40% higher short-circuit photocurrent density. However, the open circuit photovoltage of the N719 based cell is 40 mV higher than that of the organic dye C218 and D205 based devices. Investigation of the electron recombination kinetics of the NR-DSSCs has revealed that the effective electron lifetime, τ_n, of the different dye based NR-DSSCs shows the sequence of C218 > D205 > N719. The higher V_oc with the N719 based NR-DSSC is originated from the more negative energy level of the conduction band of the TiO₂ film. In addition, in comparison to the DSSCs with the conventional nanocrystalline particles based TiO₂ films, the NR-DSSCs have shown over two orders of magnitude higher τ_n when employing N719 as the sensitizer. Nevertheless, the τ_n of the DSSCs with the C218 based nanorod arrays is only ten-fold higher than that of the nanoparticles based devices. The remarkable characteristic of the dye C218 in suppressing the electron recombination of DSSCs is discussed.