Energy transfer in colloidal CdTe quantum dot nanoclusters.

Quantum dot (QD) nanoclusters were formed using oppositely charged colloidal CdTe QDs, of two different sizes, mixed in aqueous solutions. The photoluminescence (PL) spectra and time-resolved PL decays show signatures of Förster resonant energy transfer (FRET) from the donor QDs to the acceptor QD in the nanoclusters. A concentration dependence of the donor QD lifetime is observed in mixed solutions with a donor: acceptor ratio greater than 1:1. The concentration dependent time-resolved PL data indicate different regimes of cluster formation, with evidence for donor-to-donor FRET in the larger donor-acceptor nanoclusters and evidence for the formation of all-donor clusters in mixed solutions with high donor concentrations.