Enhanced photocurrent-voltage characteristics of Ru(II)-dye sensitized TiO2 solar cells with TiO2-WO3 buffer layers prepared by a sol-gel method

The influence of a buffer layer of a TiO2-WO3 composite material located between a TCO substrate and a TiO2 (P25) layer on photocurrent-voltage characteristics of dye-sensitized solar cells was compared. The buffer layer effectively isolated dye molecules and electrolytes from directly contacting the conducting substrate. In the presence of the buffer layer having 15-75 mol % WO3, both open-circuit photovoltage (V-oc) and short-circuit photocurrent (J(sc)) were enhanced. Analyses of scanning electron microscopy data and bandedge positions of the TiO2-WO3 films indicate that the V-oc and J(sc) increases are correlated with favorable energy levels for the electron injection from the P25 layer, and with improved interparticle electrical contacts at both the TCO/TiO2-WO3 and the TiO2-WO3/P25 junctions. (C) 2002 The Electrochemical Society.