CdS and CdSe quantum dot co-sensitized nanocrystalline TiO2 electrode: Quantum dot distribution, thickness optimization, and the enhanced photovoltaic performance

The anatase TiO2 nanoparticle films with different thicknesses have been fabricated through screen printing method, and CdS and CdSe quantum dots (QDs) have been deposited on TiO2 films in turn through successive ionic layer adsorption and reaction (SILAR) method. It has been found that the amount of QDs decreases significantly and the size of QDs increases obviously with the depth increasing in TiO2 nanoparticle films, and the size distribution of QDs shifts to large-size direction with the TiO2 film thickness increasing. Furthermore, a qualitative model of CdS/CdSe quantum dot distribution in TiO2 nanoparticle films has been obtained. After optimizing the TiO2 film thickness, the quantum dot-sensitized solar cells (QDSCs) with about 10 mu m thick nanocrystalline TiO2 electrodes and Pt counter electrodes have reached relatively high power conversion efficiencies of 3.26 +/- 0.10% under one sun illumination (100 mW cm(-2), AM 1.5 G). (C) 2014 Elsevier B.V. All rights reserved.