Understanding the energy flow on nanoscale is an important step towards designing artificial molecular systems with configurable optoelectronic and photochemical properties. Experimental methods for probing the intermolecular energy transfer, however, are quite challenging and often require an individual spectroscopic treatment of specific donor-acceptor combinations. The main issue concerns the spectral crosstalk in the excitation region which is prevalent in most inorganic nanostructures or complex biological systems. Here, we demonstrate a general spectroscopic strategy for measuring the energy transfer efficiency between nanostructured or molecular dyes featuring a significant donor-acceptor spectral overlap. The reported approach relies on filtering the broadband excitation light with solutions of either donor or acceptor molecules designed to selectively turn off the excitation of the respective donor or acceptor species in the sample. The resulting changes in the acceptor emission are then used to determine the quantum efficiency and the rate of the energy transfer (ET) process between arbitrary fluorephores (molecules, nanoparticles, polymers) with unprecedented accuracy. The method also allows differentiating between charge transfer and energy transfer contributions.  The feasibility of the reported method is demonstrated using two control donor-acceptor systems: a low-overlap DNA-bridged Cy3-Cy5 dye pair, and high-overlap CdSe<sub>560</sub>-CdSe<sub>610</sub> inorganic film.

Sample-Transmitted Excitation Photoluminescence (STEP) technique for quantifying the energy flow in nanocrystals and their solids

253rd National Meeting (2017)

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