Chemical Control of the Photoluminescence of CdSe Quantum Dot-Organic Complexes with a Series of Para-Substituted Aniline Ligands

TY - JOUR

T1 - Chemical Control of the Photoluminescence of CdSe Quantum Dot-Organic Complexes with a Series of Para-Substituted Aniline Ligands

AU - Knowles, K. E.

AU - Tice, D. B.

AU - McArthur, E. A.

AU - Solomon, Gemma Clare

AU - Weiss, E. A.

PY - 2010

Y1 - 2010

N2 - Replacement of the native (as-synthesized) ligands of colloidal CdSe QDs with varying concentrations of a series of para-substituted anilines (R-An), where R ranges from strongly electronwithdrawing to strongly electron-donating, decreases the PL of the QDs. The molar ratio of R-An to QD ([R-An]:[QD]) at which the PL decreases by 50% shifts by 4 orders of magnitude over the series R-An. The model employed to describe the data combines a Freundlich binding isotherm (which reflects the dependence of the binding affinity of the amine headgroups of R-An on the substituent R) with a function that describes the response of the PL to R-An ligands once they are bound at their equilibrium surface coverage. The latter function includes as a parameter the rate constant, knr, for nonradiative decay of the exciton at a site to which an R-An ligand is coordinated. The value of this parameter reveals that the predominant mechanism of QD-ligand interaction is passivation of Cd2+ surface sites through σ-donation for R-An ligands with R ) H, Br, OCF3, and reductive quenching through photoinduced hole transfer for R = MeO, (Me)2N.

AB - Replacement of the native (as-synthesized) ligands of colloidal CdSe QDs with varying concentrations of a series of para-substituted anilines (R-An), where R ranges from strongly electronwithdrawing to strongly electron-donating, decreases the PL of the QDs. The molar ratio of R-An to QD ([R-An]:[QD]) at which the PL decreases by 50% shifts by 4 orders of magnitude over the series R-An. The model employed to describe the data combines a Freundlich binding isotherm (which reflects the dependence of the binding affinity of the amine headgroups of R-An on the substituent R) with a function that describes the response of the PL to R-An ligands once they are bound at their equilibrium surface coverage. The latter function includes as a parameter the rate constant, knr, for nonradiative decay of the exciton at a site to which an R-An ligand is coordinated. The value of this parameter reveals that the predominant mechanism of QD-ligand interaction is passivation of Cd2+ surface sites through σ-donation for R-An ligands with R ) H, Br, OCF3, and reductive quenching through photoinduced hole transfer for R = MeO, (Me)2N.

M3 - Journal article

SN - 0002-7863

VL - 132

SP - 1041

EP - 1050

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 3

ER -