Fluorescence Intermittency in Single InP Quantum Dots

Published

October 1, 2001

Author(s)

M Kuno, D P. Fromm, Alan Gallagher, David Nesbitt, O I. Micic, A J. Nozik

Abstract

Fluorescence kinetics of isolated colloidal InP quantum dots (Qds) are investigated for the first time via confocal single molecule microscopyFluorescenceintermittency or blinking is observed in all QD's sampled, characterized by abrupt chanc,yes between episodes of absorption/laserinduced fluorescence and periods of darkness despite continuous laser excitation of the nanoparticle. Analysis of fluorescence trajectories forisolated InP QDs reveals an inverse power law (variation} 1/τ/m/) in both the on-time and off-time probability densities [P(τ_on) and P(τ_off)], with average power law exponents of m_on nearly equal to} -2.02 (2) and m_off nearly equal to} -1.5 (1). In the context of QD ionization models for blinking, such intrinsically non-exponential kinetics requires highly distributed rate constants (over 10²-10⁴ fold) for ejection and recombination dynamics of electron/hole pairs from single InP QD's. More fundamentally, the inverse power law in both P(τ_on) and P(τ_off) is qualitatively inconsistent with a static distributionof external sites for electron/hole trapping, and highlights the critical role of time dependent fluctuations in the local QD nanoenvironment.

Citation

Nano Letters

Volume

1

Issue

No. 10

Pub Type

Journals

Keywords

fluorescence intermittency, opoelectronics, photoionization, quantum dots

Citation

Kuno, M. , Fromm, D. , Gallagher, A. , Nesbitt, D. , Micic, O. and Nozik, A. (2001), Fluorescence Intermittency in Single InP Quantum Dots, Nano Letters (Accessed December 14, 2024)