Research Fellows Directory
Dr Jenny Clark
University of Cambridge
Chromophores are molecules which can absorb and emit light, and are the basis of most of the colours we see in nature. Chemists can create chromophores which differ from the natural ones and can perform a variety of different functions. For applications such as carbon-based lasers and solar cells (both of which should be inherently more energy efficient than their non-carbon-based alternatives), the chromophores have to be densely packed to allow excitations and charges (electrons) to easily flow from one molecule to another. However, a high density of chromophores can lead to 'concentration quenching' which limits the efficiency of both solar cells and lasers. In the past year, my co-workers and I have been attempting to understand what governs this concentration quenching and how the conformation of the chromophores, their interactions with their neighbours and disorder within the samples affect both the light emission and any quenching processes.
Recently, we published a paper describing how chromophores can change conformation significantly faster than even the primary step of vision (the cis-trans isomerisation of rhodopsin in the eye was previously thought to be the fastest conformational change every measured). This ultrafast conformational change is accompanied with a large energy loss. (Published in Nature Physics).
In another paper published this year, I collaborated with researchers in Singapore to demonstrate how the intensity of light absorbed by the chromophore (in this case graphene oxide) changes its excited-state properties, leading to rapid quenching of the highly delocalised excitations at high light intensities. (Published in Nature Photonics).