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2 for 1: Quantum Dynamics of Singlet Fission

Periodic Reporting for period 1 - 2for1-SingletFission (2 for 1: Quantum Dynamics of Singlet Fission)

Reporting period: 2016-10-05 to 2018-10-04

This project was motivated by the need for developing renewable energy sources in an effort to mitigate the effects of climate change. We focussed on the development of next generation solar cells. While conventional solar cell technology is already competitive when compared to the cost of fossil fuel electricity generation, we are looking toward a future where increased energy demands and limited land area will necessitate highly efficient solar energy harvesting devices.

Conventional solar cell technology is limited to an energy conversion efficiency of 34%. This is because sunlight is comprised of a spectrum of colours, ranging from high energy ultraviolet to low energy infra-red light. Conventional solar cells are designed to harvest one energy of light efficiently. Higher energy light is harvested, but generates heat losses and low energy light is not harvested at all. In this project we studied a class of molecules which undergo a process called ‘singlet fission’ which allows for the generation of two excited molecules from one quanta of light. This allows us to engineer the solar spectrum with the intention of developing more efficient solar cells.

Singlet fission is still not completely understood. Of particular interest is the intermediate state in the singlet fission process and the effects of molecular orientation. The objectives of this project are to gain further insight into the process on rapid timescales (in some experiments less than 1 millionth of 1 millionth of a second!) by using a combination of optical and magneto-optical spectroscopies.
During this project several molecular systems were studied using a range of experimental techniques. This provided an overarching model of singlet fission, ranging from picoseconds (1 millionth of a millionth of a second) to microseconds (1 millionth of a second).

These results were disseminated via 2 international conferences, 3 peer-reviewed journal articles, and one public event (Marie Curie Falling Walls Lab as part of the Science is Wonder-ful event). It is expected that this project will contribute to a further 4 publications.
The understanding of singlet fission is evolving rapidly. The contributions from this project are understanding subtleties. The final outcome of the project was to develop potential molecular design pathways for the development of the next generation of molecular solar cells. This will potentially impact upon the development of next generation solar cells, lowering the cost of renewable energy and contributing towards a sustainable future.
Winners of the international Marie Curie Falling Walls Lab (image courtesy of: https://ec.europa.eu/