Slow Electron Injection on Ru-Phthalocyanine Sensitized TiO_2

摘要

The function of dye sensitized solar cells is based upon photoinduced electron injection from a molecular excited-state into the conduction band of a nanocrystalline metal oxide film. Over the last 10 years, extensive studies of model systems based on dye sensitized metal oxide films have demonstrated that such interfacial electron transfer can occur on remarkably fast time scales. Nevertheless it remains an open question as to whether such ultrafast injection dynamics are necessary for efficient device function. We have recently reported charge injection dynamics on the 100 ps-1 ns time scale for a range of ruthenium bipyridyl dyes adsorbed to TiO_2 in the presence of redox electrolytes. We have suggested that such relatively slow injection dynamics are still fast enough to compete effectively with excited-state decay-to-ground, and therefore are consistent with efficient device function.