Solar energy is an attractive renewable energy source as the world-wide energy consumption is less than 0.02% of the total solar energy hitting Earth’s surface. The invention of transition metal complexes – capable of absorbing sunlight and converting this energy into electricity or solar fuels in an efficient manner – is therefore highly desirable. By far the most research has until now focused on transition metal complexes based on precious platinum group metals. The use of Earth-abundant metals in light-activated processes is, however, an obvious goal to secure cheaper and sustainable technologies in the future. Whereas this is desirable, the reality is that it is challenging because most transition metal complexes based on Earth-abundant metals suffer from rapid excited state depopulation and photochemical applications are consequently hampered. This detrimental effect is caused by the inherent weak ligand field present in most transition metal complexes of Earth-abundant metals.
In my research group, we aim at overcoming this fundamental challenge by using rational ligand design strategies to construct novel photoactive transition metal complexes based on Earth-abundant metals such as manganese, iron, and zinc. As we are aiming for good absorption properties, our compounds have beautiful colors.
We use a large range of spectroscopy techniques to obtain in-depth understanding of the electronic structure of the transition metal complexes and their resulting photoactivity. We are particularly interested in elucidating excited state dynamics with a clear focus on boosting photophysical performance. Besides traditional steady-state spectroscopy techniques, we use advanced pump-probe laser spectroscopy setups to characterize the excited state landscape.
The light-harvesting applications relevant for our photoactive transition metal complexes span from photocatalysis and phototherapeutics to microscopy and dye-sensitized solar cells.