CdS/TiO2-SrTiO3 heterostructure nanotube arrays for improved solar energy conversion efficiency

TiO2-SrTiO3 heterostructure nanotube arrays have been utilized as a novel oxide substrate for CdS quantum dot sensitized solar cells (QDSCs). SrTiO3 on TiO2 surface passivates surface states of TiO2 and builds cascade-structured band alignment, which significantly reduces charge recombination at electrode surface. CdS/TiO2-SrTiO3 electrode exhibits a superior photoelectrochemical performance than CdS/TiO2 electrode with similar to 70% increase in external quantum efficiency. This study suggests that the suppression of charge recombination at electrode surface is critical to efficient solar energy conversion. (C) 2010 Elsevier B.V. All rights reserved.