Tunable Electronic Structure via DNA-Templated Heteroaggregates of Two Distinct Cyanine Dyes

Molecular excitons are useful for applications in light harvesting, organic optoelectronics, and nanoscale computing. Electronic energy transfer (EET) is a process central to the function of devices based on molecular excitons. Achieving EET with a high quantum efficiency is a common obstacle to exc...

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Published in:Journal of physical chemistry. C 2022-10, Vol.126 (40), p.17164-17175
Main Authors: Huff, Jonathan S., Díaz, Sebastián A., Barclay, Matthew S., Chowdhury, Azhad U., Chiriboga, Matthew, Ellis, Gregory A., Mathur, Divita, Patten, Lance K., Roy, Simon K., Sup, Aaron, Biaggne, Austin, Rolczynski, Brian S., Cunningham, Paul D., Li, Lan, Lee, Jeunghoon, Davis, Paul H., Yurke, Bernard, Knowlton, William B., Medintz, Igor L., Turner, Daniel B., Melinger, Joseph S., Pensack, Ryan D.
Format: Article
Language:English
Subjects:
absorption
C: Spectroscopy and Dynamics of Nano, Hybrid, and Low-Dimensional Materials
cyanine dye Cy5 and Cy5.5 heteroaggregates
dyes and pigments
electrical energy
electronic energy transfer
fluorescense resonance energy transfer
Förster resonance energy transfer
H- and J-aggregates
Molecular excitons
monomers
NANOSCIENCE AND NANOTECHNOLOGY
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Summary:Molecular excitons are useful for applications in light harvesting, organic optoelectronics, and nanoscale computing. Electronic energy transfer (EET) is a process central to the function of devices based on molecular excitons. Achieving EET with a high quantum efficiency is a common obstacle to excitonic devices, often owing to the lack of donor and acceptor molecules that exhibit favorable spectral overlap. EET quantum efficiencies may be substantially improved through the use of heteroaggregatesaggregates of chemically distinct dyesrather than individual dyes as energy relay units. However, controlling the assembly of heteroaggregates remains a significant challenge. Here, we use DNA Holliday junctions to assemble homo- and heterotetramer aggregates of the prototypical cyanine dyes Cy5 and Cy5.5. In addition to permitting control over the number of dyes within an aggregate, DNA-templated assembly confers control over aggregate composition, i.e., the ratio of constituent Cy5 and Cy5.5 dyes. By varying the ratio of Cy5 and Cy5.5, we show that the most intense absorption feature of the resulting tetramer can be shifted in energy over a range of almost 200 meV (1600 cm–1). All tetramers pack in the form of H-aggregates and exhibit quenched emission and drastically reduced excited-state lifetimes compared to the monomeric dyes. We apply a purely electronic exciton theory model to describe the observed progression of the absorption spectra. This model agrees with both the measured data and a more sophisticated vibronic model of the absorption and circular dichroism spectra, indicating that Cy5 and Cy5.5 heteroaggregates are largely described by molecular exciton theory. Finally, we extend the purely electronic exciton model to describe an idealized J-aggregate based on Förster resonance energy transfer (FRET) and discuss the potential advantages of such a device over traditional FRET relays.
ISSN:1932-7447
1932-7455
DOI:10.1021/acs.jpcc.2c04336