CdSe@CdS core-shell quantum dot-polymer multilayer sensitized TiO2 for photovoltaics

Colloidal CdSe@CdS core-shell quantum dots (QDs) have been prepared and exploited as inorganic dyes to sensitize a large-band-gap TiO2 layer for QD-sensitized solar cells. The sensitized films were prepared by alternating the layer-by-layer deposition of water-soluble semiconductor QDs and polycations over mesoscopic TiO2 films. The multilayer build-up, monitored by UV-vis spectroscopy shows an increase in the film absorbance with the number of adsorbed CdSe@CdS layers. The photoluminescence (PL) and photoelectrochemical properties of the multilayers were investigated. The photovoltaic performance of QD-sensitized solar cells is strongly dependent on the film structure and component. The incorporation of the electron mediators of [Co(Phen)3]2+ during the deposition process remarkably enhanced the photocurrent intensity in comparison to that in case of QD/polyelectrolyte multilayers.