SINGFISS · Singlet exciton fission as a route to more efficient dye-sensitized solar cells

One of the greatest scientific challenges of the coming decades will be to produce sufficient energy to meet consumption demands, particularly as fossil fuel reserves decline. A leading alternative method of producing energy is the conversion of solar energy to electricity. At present, energy produced by photovoltaic cells is significantly more expensive than that obtained by burning fossil fuels. Therefore, we need to find a method of producing solar cells more cheaply. The prime example of such a cheap solar cell is the dye-sensitized solar cell. However, the efficiency of these cells is currently too low to be commercially interesting. In this project, a process called singlet exciton fission is proposed as a new route to more efficient dye-sensitized solar cells. In this process, a singlet excited state formed by photo-excitation converts into a pair of triplet states by a spin-allowed transition. When both triplet excited states lead to a charge separation event, the theoretical maximum efficiency of dye sensitized solar cells can be increased from 32% to ~46% for a cell combining a singlet fission absorber with a normal dye. This project will have a two-fold benefit: it will be the first major systematic study of the fundamentals of the singlet fission process, and it will explore the use of singlet fission dyes in photovoltaics. Using a variety of disciplines, ranging from organic synthesis to ultrafast spectroscopy and quantum chemical calculations, this project will deliver the clearest picture yet of the exciton fission process. In addition, this research will enable the design of specific chromophores possessing optimal triplet fission yield and, by doing so, will open exciting new possibilities for the production of more efficient dye-sensitized solar cells.