In solar cells, the ability to absorb one photon and harvest two electrons can lead to internal quantum efficiencies of up to 200%. This is possible using organic semiconductors via a process known as ’singlet exciton fission’ (SEF), where the primary excited state (singlet exciton) can split into two distinct triplet excitons which can both be harvested.
SEF has also been shown to occur in naturally occurring carotenoids such as astaxanthin and zeaxanthin, but we have recently demonstrated that current theory does not adequately describe SEF in these systems.
The proposed project will involve using time-resolved ultrafast spectroscopy in Sheffield’s new laser facility to study SEF in carotenoids. The main outcomes of the project will be two-fold: 1. to develop a new description of this SEF process in collaboration with theoreticians, enabling future design of efficient SEF materials for solar cell applications. 2. to determine whether SEF in carotenoids has a biological role.