Chemical control of the photoluminescence of CdSe quantum dot-organic complexes with a series of para-substituted aniline ligands.
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 electron-withdrawing 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, k(nr), 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 Cd(2+) surface sites through sigma-donation for R-An ligands with R = H, Br, OCF(3), and reductive quenching through photoinduced hole transfer for R = MeO, (Me)(2)N.
Knowles
Kathryn E
KE
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
Tice
Daniel B
DB
McArthur
Eric A
EA
Solomon
Gemma C
GC
Weiss
Emily A
EA
D000814:Aniline Compounds / Q000737:chemistry*; D019187:Cadmium Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000302:isolation & purification; D008024:Ligands; D049449:Luminescence; D008163:Luminescent Measurements; D009942:Organometallic Compounds / Q000737:chemistry*; D010316:Particle Size; D045663:Quantum Dots; D018036:Selenium Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000302:isolation & purification; D013499:Surface Properties
D000814:Aniline Compounds; D019187:Cadmium Compounds; D008024:Ligands; D009942:Organometallic Compounds; D018036:Selenium Compounds; C058667:cadmium selenide; C023650:aniline