The influence of the time-of-flight mobility on the efficiency of solid-state dye-sensitized TiO2 solar cells

The dependence of zero field charge carrier mobilities obtained from time-of-flight (TOF) measurements for a series of doped triphenyldiamines on trap depth and concentration were determined. The influence of these mobilities on the solar cell characteristics have been studied by measuring I–V characteristics and IPCE values using the same doped hole conductors in solid-state dye-sensitized TiO2 solar cells. The traps exhibit only a weak influence on the solar cell characteristics, because the traps which are responsible for low charge transport mobilities in the TOF experiment are filled under steady state illumination conditions. In consequence the effective mobility is raised almost to that of the pristine hole conductor, thus allowing the use of doped hole conductor systems in solar cells without any adverse effects.