Enhancement of Molecular Fluorescence by Excitonic Coupling to a J-Aggregate Critically Coupled Resonator

Wednesday, October 19, 2011: 5:20 PM
102 B (Minneapolis Convention Center)
Gleb M. Akselrod1, Brian J. Walker2, William A. Tisdale3, Moungi G. Bawendi2 and Vladimir Bulovic1, (1)Organic and Nanostructured Electronics Lab, MIT, Cambridge, MA, (2)Department of Chemistry, MIT, Cambridge, MA, (3)Organic and Nanostructured Electronics Lab, and Department of Chemical Engineering, MIT, Cambridge, MA

The efficient absorption and reemission of light is of fundamental importance to the operation of optoelectronic devices in applications such as high efficiency lighting, lasers, chemical sensing, solar concentrators, and optical imaging. However, the properties that determine the brightness of molecules and other luminescent species – the absorption cross section and emission quantum yield – are not easily altered without affecting spectral properties. In cases where the excitation intensity is limited and/or the luminophore is expensive, a strategy for enhancing effective absorption cross section would be highly valuable. With this motivation in mind, we report a device for the scalable, tunable, and homogeneous enhancement of molecular fluorescence. The operation of this device, called a J-aggregate critically coupled resonator (JCCR), is based on excitonic energy transfer from a highly absorptive thin film of J-aggregating dye molecules positioned at the anti-node of an optical half-cavity. We demonstrate the feasibility of this scheme through enhancement of fluorescence from the laser dye DCM. A sub-monolayer equivalent of DCM molecules is shown to absorb and reemit 2.2% of incident photons when coupled to the JCCR enhancement structure, compared to 0.1% for the bare film. We discuss quantitatively the role of optical interference, Förster resonance energy transfer, and exciton diffusion in optimizing the device geometry.

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