Physicists from the University of Gettingen came up with how look into the heart solar panels and trace the work “Dark” excitons – particles that determine how effective the battery turns light into electricity. Now scientists can not only see these particles, but also accurately track their path.
What is a dark exciton? The electron, having received a portion of energy, jumps to a new place, but at the same time remains associated with the void that he left. Physicists call this void a “hole”, and the strength between it and the electron – Kulonov’s interaction. The simplest example: a balloon that cannot fly far from the place to which is tied with a rope.
These particles were called dark because they can transfer energy, but are not able to radiate light. It is extremely difficult to notice them. At the same time, dark excitons are extremely important for the manufacture of special materials – semiconductors with a thickness of only one atom.
Professor Stefan Matias and his colleagues from the Faculty of Physics of the University of Gettingen have been exploring the properties of these particles for several years. In one of the recent works, they first described how long the dark excitons are formed, and developed a quantum-mechanical theory that explains their dynamics.
In the new work, physicists went further and created a special device – “Super -building dark -button microscope” (Ultrafast Dark -Field Momentum Microscopy). With its help, it was possible to trace for the first time how dark excitons are born in unusual material from Disulframa (WSE₂) and molybdenum disulfide (mos₂).
The accuracy of observations is amazing: scientists were able to see how the excitons appear in 55 femtoseconds, and determine their position with an accuracy of 480 nanometers.
“Now we know exactly how the properties of the material affect the behavior of particles inside it. This will help make solar panels much more effective,” explains Dr. Marseille Roitzel, who leads the youth research group in the Matias team. He adds that the new method is useful not only for studying already known materials – with its help it will be possible to study completely new substances.