Size-Dependent Electron Injection from Excited CdSe Quantum Dots into TiO_2 Nanoparticles

摘要

Semiconductor quantum dots such as CdSe, PbSe, and InAs with their tunable band gaps offer new opportunities for harvesting light energy in the visible and infrared regions of solar light. Early efforts demonstrated the ability of chemically and electrochemically deposited CdS and CdSe nanostructures on TiO_2, SnO_2, and ZnO to generate photocurrent under visible light irradiation. By making use of size quantization effects, one can readily tune the photoresponse of the electrode. We report here modulation of the interparticle electron transfer rate by varying the QD particle size. Femtosecond transient absorption measurements, elucidating the size-dependent electron injection rate from excited CdSe into TiO_2 nanoparticles, are described.