Hybrid energy harvester mimics photosynthesis

Research at a number of universities – Sheffield, Southampton and Crete – is aiming to develop a new hybrid energy transfer system that mimics the processes responsible for photosynthesis.

The device trapping photons between two mirrors in which two different organic molecules reside

The device trapping photons between two mirrors in which two different organic molecules reside

This energy transfer, writes Richard Wilson, is known as Forster Resonance Energy Transfer (FRET), a radiationless transmission of energy that occurs on the nanometer scale from a donor molecule to an acceptor molecule.

The donor molecule is the dye or chromophore that initially absorbs the energy and the acceptor is the chromophore to which the energy is subsequently transferred without any molecular collision.

The energy transfer technique is highly distance dependent and occurs over a scale of typically 1 to 10nm.

In a new study, published in the journal Nature Materials, the researchers demonstrate an alternate non-radiative, intermolecular energy transfer that exploits the intermediating role of light confined in an optical cavity.

“The advantage of this new technique which exploits the formation of quantum states admixture of light and matter, is the length over which the interaction takes places, that is in fact, considerably longer than conventional FRET-type processes,” said the researchers.

According to Dr Niccolo Somaschi, from the University of Southampton’s Hybrid Photonics group: “The possibility to transfer energy over distances comparable to the wavelength of light has the potential to be of both fundamental and applied interest.”

“Our deep understanding of energy transfer elucidates the basic mechanisms behind the process of photosynthesis in biological systems and therefore gets us closer to the reproduction of fully synthetic systems which mimic biological functionalities. At the fundamental level, the present work suggests that the coherent coupling of molecules may be directly involved in the energy transfer process which occurs in the photosynthesis,” said Somaschi.

The new device consists of an optical cavity made by two metallic mirrors which trap the photons in a confined environment where two different organic molecules reside in.

The researchers believe that by engineering the spacing between the mirrors based on the optical properties of the organic materials, it is possible to create a new quantum state that is a combination of the trapped photons and the excited states in the molecules.

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