Electrochemical and spectroelectrochemical techniques were employed to investigate
the redox characteristics of dyes for dye sensitized solar cells (DSCs) adsorbed at the
surface of fluorine-doped tin oxide (FTO) and FTO TiO2 electrodes. In this work are
studied Ru-based dyes such as cis-bis(isothiocyanato)-bis(2,2’-bipyridyl-
4,4’dicarboxylato)-ruthenium(II) (N719) and (cis-RuLL'(SCN)2 with L=4,4'-
dicarboxylic acid-2,2'-bipyridine and L'=4,4'-dinonyl-2,2'-bipyridine) known as Z907,
and indoline organic dyes coded as D102, D131, D149, and D205.
The adsorption, diffusion and stability of adsorbed dyes were studied using cyclic
voltammetry in acetonitrile and 0.1 M NBu4PF6. The adsorption technique at FTO
electrodes was optimized in order to be reproducible so that electrochemical studies
as a function of dye coverage were carried out. Langmuirian binding constants were
approximately estimated for all dyes adsorbed at FTO electrodes.
Rate constants for the chemical degradation of the oxidized dye were also obtained.
Is shown that degradation of the dyes mainly occurs at the surface of FTO and only
insignificant degradation is evident once the dyes are adsorbed on TiO2. The
degradation of dye adsorbed on FTO is shown to affect charge transport from the
nonporous TiO2 via electron hopping.
Spectroelectrochemical studies of indoline dyes adsorbed on FTO/TiO2 electrodes
revealed a red shift of absorption peaks after oxidation and the presence of a strong
charge transfer band in the near IR that suggest delocalization of holes in the dye
layer. This is consistent with observation that the diffusion coefficient for hole
conduction in the adsorbed dye layer is several orders of magnitude higher for the
organic dyes compared to the Ru-based dyes.
DSCs fabricated using indoline dyes showed good performance. Incident photon-tocurrent
conversion efficiency (IPCE) spectra and I-V characteristics are presented.
|Date of Award||1 Apr 2010|
|Supervisor||Laurie Peter (Supervisor)|
- dye cells
- cyclic voltammetry