| Abstract
| - We report on the effects of Lewis bases and other ligands on radiative recombination in CdSe quantum dots (QDs)in several solvents. Long-chain primary amines are found to be the most efficacious capping agents for CdSe QDsin nonpolar solvents. Primary alkylamines are superior to secondary and tertiary alkylamines. The kinetics of chemisorptionand desorption in less polar solvents, such as hexane or chloroform, are temperature controlled and obey a Langmuirisotherm. Mercaptan adsorption also obeys a Langmuir isotherm, and alkylmercaptans rapidly displace amines, leadingto luminescence quenching. In more polar solvents, such as toluene, ligands desorb, leading to luminescence quenching.It is proposed that surface Cd vacancies function as nonradiative recombination centers. The adsorption of a Lewisbase to the QD raises the surface vacancy energy close to, or above, the conduction band edge and eliminates electroncapture by the surface vacancies. Solvent polarity has a strong effect on luminescence since the solvent determinesthe extent of ligand adsorption to the QD surface.
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