Highly efficient dye-sensitized SnO2 solar cells having sufficient electron diffusion length

Dye-sensitized solar cells (DSCs) were fabricated from mesoporous SnO2 electrodes, which were prepared from nano-sized SnO2 particles. Current–voltage characteristics of the DSCs were compared with DSCs prepared from conventional TiO2 electrodes, which have similar amount of adsorbed dye with the SnO2. As a result, short-circuit current of the SnO2DSC were comparable with that of the TiO2DSCs, and more than 15 mA/cm2 was obtained with the SnO2 at the thickness of 10 μm under one sun conditions. Electron diffusion coefficients and lifetimes in the SnO2 and TiO2 electrodes were measured, showing slower diffusion and longer lifetime in the SnO2DSC than in the TiO2. The results imply that the electron transport and transfer dynamics in such electrodes is dominated by the influence of intra-band charge traps, and the control of the trap conditions would be the key strategy to employ various metal oxides for such solar cells.