Radiative and Nonradiative Lifetime Engineering of Quantum Dots in Multiple Solvents by Surface Atom Stoichiometry and Ligands

CdTe quantum dots have unique characteristics that are promising for applications in photoluminescence, photovoltaics, or optoelectronics. However, wide variations of the reported quantum yields exist, and the influence of ligand–surface interactions that are expected to control the excited state re...

Full description

Saved in:
Bibliographic Details
Published in:Journal of physical chemistry. C 2013-02, Vol.117 (5), p.2317-2327
Main Authors: Omogo, Benard, Aldana, Jose F, Heyes, Colin D
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Exact sciences and technology
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures
Physics
Quantum dots
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:CdTe quantum dots have unique characteristics that are promising for applications in photoluminescence, photovoltaics, or optoelectronics. However, wide variations of the reported quantum yields exist, and the influence of ligand–surface interactions that are expected to control the excited state relaxation processes remains unknown. It is important to thoroughly understand the fundamental principles underlying these relaxation processes to tailor the QDs properties to their application. Here, we systematically investigate the roles of the surface atoms, ligand functional groups, and solvent on the radiative and nonradiative relaxation rates. Combining a systematic synthetic approach with X-ray photoelectron, quantitative FT-IR, and time-resolved visible spectroscopies, we find that CdTe QDs can be engineered with average radiative lifetimes ranging from nanoseconds up to microseconds. The nonradiative lifetimes are anticorrelated to the radiative lifetimes, although they show much less variation. The density, nature, and orientation of the ligand functional groups and the dielectric constant of the solvent play major roles in determining charge carrier trapping and excitonic relaxation pathways. These results are used to propose a coupled dependence between hole trapping on Te atoms and strong ligand coupling, primarily via Cd atoms, that can be used to engineer both the radiative and nonradiative lifetimes.
ISSN:1932-7447
1932-7455
DOI:10.1021/jp309368q