Effects of Al₂O₃ atomic layer deposition on interfacial structure and electron transfer dynamics at Re-bipyridyl complex/TiO₂ interfaces

Atomic layer deposition (ALD) of oxide layers on sensitizer- and/or catalyst-functionalized semiconductor surfaces have been used to improve the stability of dye-sensitized solar cells and photoelectrosynthesis cells. However, how the ALD layer affects the interfacial structure of adsorbed molecules and interfacial electron transfer dynamics is still unclear. Herein, we investigated the effects of ALD of Al₂O₃ on adsorption structure of Re bipyridyl complex on TiO₂ nanocrystalline films and rutile (0 0 1) single crystals by IR absorption and sum frequency generation spectroscopy. Further, the electron transfer dynamics between the Re complex and TiO₂ film was also examined by ultrafast infrared transient absorption spectroscopy. Our results show that the electron injection yield decreases with the increase of ALD layer thickness.