LONG-RANGE RESONANCE TRANSFER OF ELECTRONIC EXCITATIONS IN CLOSE-PACKED CDSE QUANTUM-DOT SOLIDS

We show spectroscopically that electronic energy transfer in close-pac ked CdSe quantum-dot (QD) solids arises from dipole-dipole interdot in teractions between proximal dots. We use cw and time-resolved photolum inescence to study electronic energy transfer in optically thin and cl ear, close-packed QD solids prepared from CdSe QD samples tunable from 17 to 150 Angstrom in diameter (sigma<4.5%). High-resolution scanning electron microscopy and small-angle x-ray scattering are used to buil d a well-defined structural model for the QD solids. In mixed QD solid s of small and large dots, we measure quenching of the luminescence (l ifetime) of the small dots accompanied by enhancement of the luminesce nce (lifetime) of the large dots consistent with electronic energy tra nsfer from the small to the large dots. In QD solids of single size do ts, a redshifted and modified emission line shape is consistent with e lectronic energy transfer within the sample inhomogeneous distribution . We use Forster theory for long-range resonance transfer through dipo le-dipole interdot interactions to explain electronic energy transfer in these close-packed QD solids.