Figure: Schematic band structure of a semiconductor. Red is the indirect transition (with pulse transfer), green the direct transition (without pulse transfer).
Semiconductors
Semiconductors are omnipresent in our daily life: in computers, mobile phones, screens, solar cells... The development of improved semiconductors is therefore an important area of research.
A disadvantage of the elements silicon and germanium, which are widely used today, is the indirect transition of electrons from the conduction band to the valence band, which cannot be excited by light. This leads, for example, to a reduced current yield in solar cells.
We investigate novel semiconductor materials with direct band transitions, e.g. low-dimensional layers of transition metal dichalcogenides (prototype: MoS2).
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Solar Cells
Solar cells are perhaps the most important energy source of the future. Our research is focused on both unconventional new solar cells made from cheap raw materials and traditional solar cells made from silicon.