Electronic properties of adjoined TiO

Submitted for the MAR08 Meeting of The American Physical Society Electronic properties of adjoined TiO2 nanocrystals1 O. DIWALD, M.J. ELSER, N. SIEDL, Vienna University of Technology, Institute of Materials Chemistry, J. BERNARDI, Vienna University of Technology, USTEM — The discussion of particle attachment effects is indispensable for deeper insights into electronic conduction across grain boundaries and thus essential to photovoltaics. We investigated the condensation of isolated TiO2-nanocrystals [1] induced via the application of a simple hydration-dehydration cycle. The resulting particle network shows a mesoporous structure as well as significant changes in the optical absorption properties as investigated by UV-diffuse reflectance spectroscopy. In addition, polarizable conduction band electrons are only observed in the network which consists of adjoined TiO2-nanocrystals [2]. Since photo-assisted tunneling between localized states in the oxide particle network represents an important conduction mechanism in dye-sensitised solar cells, UV induced charge separation processes were studied on nanocrystal aggregates using EPR and IR spectroscopy. Corresponding results will be discussed in the light of associated structural data. [1] Berger et al. Chem. Phys. Chem. 2005 6 2104-2112 [2] Elser et al. J. Phys. Chem. B 2006, 110, 7605 1Financial support from the Austrian Fonds zur Foerderung der wissenschaftlichen Forschung (P19702-N20) is gratefully acknowledged. Oliver Diwald Vienna University of Technology, Institute of Materials Chemistry Date submitted: 23 Nov 2007 Electronic form version 1.4