How the nature of triphenylamine-polyene dyes in dye-sensitized solar cells affects the open-circuit voltage and electron lifetimes.

Three donor-linker-acceptor triphenylamine-based cyanoacrylic acid organic dyes used for dye-sensitized solar cells (DSCs) have been examined with respect to their effect on the open-circuit voltage (V(oc)). Our previous study showed a decrease in V(oc) for DSCs based on dyes with increased molecular size (increased linker conjugation). In the present study, we investigate the origin of V(oc) with respect to (i) conduction band (E(CB)) positions of TiO(2) and (ii) degree of recombination between electrons in TiO(2) and electrolyte acceptor species at the interface.

Recombination and transport processes in dye-sensitized solar cells investigated under working conditions.

The transport and recombination of electrons in dye-sensitized TiO(2) solar cells were studied by analysis of the current and voltage response to a small square-wave light-intensity modulation. Solar cells were studied under working conditions by using potentiostatic and galvanostatic conditions. An increase in applied voltage, that is, from 0 V toward open-circuit voltage, was found to lead to faster electron transport at low light intensities, while it slowed transport at higher light intensities.