Extraction of electrons and holes photogenerated in Use quantum dots (QD) of 2.3 nm diameter, is monitored by Surface Photovoltage Spectroscopy. The extraction of electrons into a thin TiO2 layer increases five-fold by absorption of N3 dye molecules on top of the QD layer. This process is facilitated by efficient hole extraction from the valence band of the QDs to the ground state of the N3 dye. Our results represent a direct measurement of charge separation in the N3/QD/TiO2 system. (c) 2007 Elsevier B.V. All rights reserved.