Tuning flat band potential of TiO 2 using an electrolyte additive to enhance open circuit voltage and minimize current loss in dye sensitized solar cells

Electrolyte is an important component of dye sensitised solar cells (DSSC). Its composition, in particular, additives controls the energetic at the TiO2/dye/electrolyte interface, influencing the performance of dye solar cell. We report here for the first time the use of 8-Hydroxyquinoline (8HQ) as an electrolyte additive to replace costly, volatile 4-tert-butyl pyridine (TBP). Due to its unique structural feature containing hydroxyl and amine group, 8HQ results in remarkable difference in the energy band alignment at the TiO2/dye/electrolyte interface with respect to that of TBP, as revealed by photocurrent density and Mott-Schottky analysis. Apart from this band shift, 8HQ is very effective in suppressing back electron transfer resulting in enhancement in open circuit voltage. Compared to TBP, additive 8HQ resulted in ∼22% increase in Jsc, with minor loss in Voc (∼5.8%) and 15% increase in photoconversion efficiency with N3 dye. Overall, we found that 8HQ is a highly effective additive in tailoring the TiO2/dye/electrolyte interface which results in superior performance of dye sensitized solar solar cells as compared to cells with TBP as the additive.