Electrostatic Formation of Quantum Dot/J-aggregate FRET Pairs in Solution

Publication Type:

Journal Article

Source:

J. Phys. Chem. C, ACS Publications, Volume 113, Issue 23, p.9986-9992 (2009)

Keywords:

2009, 2013 and earlier

Abstract:

We report the formation and photonic properties of CdSe/ZnS quantum dot (QD)/J-aggregate donor−acceptor Forster resonant energy transfer (FRET)
pairs that are electrostatically bound and dispersed in water. Assembly
occurs when the positively charged dye,
1,1′,3,3′-tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine
(TTBC), binds electrostatically to QDs that are coated with a negatively
charged amphiphilic polymer. QD/J-aggregate FRET pairs display the
broadband absorption in the visible and the ultraviolet (UV) part of the
spectrum typical of quantum dots, along with the narrow emission
linewidths characteristic of J-band emitters (∼12 nm full width at
half-maximum). We use dynamic light scattering, transmission electron
microscopy, photoluminescence spectroscopy, and photoluminescence
lifetimes to conclude that the size of the aggregates formed in the
presence of QDs is between 1−6 nm. We find the FRET radius of the
QD/J-aggregate to be 5.1 nm. We further demonstrate electrostatic binding
as a general synthetic strategy for these types of FRET pairs by attaching
a negatively charged J-aggregate (BIC) to a quantum dot coated with
positively charged ligands.