Electrolyte effects on photoelectron injection and recombination dynamics in dye-sensitized solar cells

In this study, the influence of electrolyte on the charge recombination, electron injection efficiency (phi(inj)) and performance of dye-sensitized solar cells (DSCs) was investigated. A negative shift in the flatband potential (V-fb) of the TiO2 electrode indicated that 1-methylbenzimidazole (MBI) chemisorbed on the TiO2 surface and reduced the Li+ adsorption in the nanostructured electrode. Electrochemical impedance spectra for the DSCs showed that the addition of MBI in the Lil electrolyte could increase the electron lifetime and reduce the rate constant (k(et)) for I-3- reduction with electrons in the TiO2 conduction band. The increase in V-oc for solar cells with MBI was mainly attributed to the negative shift in the V-fb of the TiO2 electrode and the decrease of recombination reaction at the dyed TiO2/electrolyte interface. Analysis of the short-circuit current density (J(sc)) depended on the light intensity for dye-sensitized solar cells indicated that there was no obvious effect on phi(inj) when the Lil concentration was up to 0.7 M in the electrolyte. Due to the negative shift in V-fb, of the TiO2 electrode by the addition of MBI in the electrolyte, phi(inj) could be reduced to obtain a decreased (C) 2010 Elsevier B.V. All rights reserved.