Structural design of ruthenium sensitizer compatible with cobalt electrolyte for a dye-sensitized solar cell

Chia Li, Shi Jhang Wu, Chun Guey Wu

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Two heteroleptic ruthenium complexes, SJW-B18 and CYC-B11H, with four alkyl groups and two alkyl groups, respectively, on the terminal of their ancillary ligand were prepared. These two complexes have a similar absorption profile, energy level and orbital distribution of the frontier orbitals. Therefore, they are good model compounds to explore the effect of the molecular structure of a ruthenium sensitizer on their photovoltaic performance, especially when cobalt electrolyte was used in assembling the device. When I-/I3- electrolyte was employed, the dye-sensitized solar cell based on SJW-B18 and CYC-B11H sensitizers achieved similar power conversion efficiencies of 9.54% and 9.64%, respectively, because the two dyes have similar optical and electronic properties. Nevertheless, when Co(II)/(III) electrolyte was used, the SJW-B18 sensitized device has a higher efficiency (7.30%) than the CYC-B11H-based cell (6.65%), mainly in higher open-circuit voltage (0.829 V vs. 0.784 V). Electrochemical impedance and intensity modulated photocurrent/photovoltage spectroscopic data reveal that the SJW-B18 dyed titanium dioxide (TiO2) anode has better surface protection compared to the CYC-B11H adsorbed TiO2 film. The physical insulation of the TiO2 surface with the four alkyl groups on the SJW-B18 dye can reduce the charge recombination between the electron on TiO2 and Co(III) to increase the open circuit voltage, and the power conversion efficiency of the device. These results provide a new strategy for designing ruthenium sensitizers which are compatible with a cobalt-based electrolyte. This journal is

Original languageEnglish
Pages (from-to)17551-17560
Number of pages10
JournalJournal of Materials Chemistry A
Volume2
Issue number41
DOIs
StatePublished - 7 Nov 2014

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