Designing semiconducting metasurfaces for solar energy harvesting using ultrafast spectroscopy

What? The demand for sustainable energy is larger than ever. Solar energy is the most abundant renewable energy resource on the earth. Harvesting this energy and storing it holds great potential in the green transition. However, the current photovoltaic and solar fuel technologies do not meet the high demand and we need to think in new directions. Why? We need an efficient way to chemically transform compounds into high-energy solar fuels that can be stored when the sun is not shining. This can be achieved by heterogeneous photocatalysis and photoelectrochemistry. However, these techniques still have severe limitations. Most notably, their absorption of solar light and the conversion of the absorbed energy into solar fuels for storage. How? I will study semiconducting NIR materials, such as GaAs or silicon, made with a specific surface geometry to tune the energy band gap. The processes I will specifically look at are those that occur when the material is illuminated by light. These processes happen at very fast timescales down to picoseconds and therefore require highly specialized spectroscopic equipment.