Tag

Charge Carriers

All articles tagged with #charge carriers

science-and-technology2 years ago

Observing the First Femtoseconds of Photoinjection with Laser Physics

Laser physicists have directly observed the first few femtoseconds after photoinjection with a strong laser pulse, revealing how the optical properties of silicon and silicon dioxide evolve during this time. The attoworld team of LMU and the Max Planck Institute of Quantum Optics used a novel technique for optical-field-resolved pump-probe measurements to observe how charge carriers interacted with a weak test pulse during the first femtoseconds after their appearance. The findings could eventually help achieve future signal processing in the petahertz range, making so-called light wave electronics possible.

science-and-technology2 years ago

"Photon Splitting: From One to Four Charge Carriers"

Researchers have recorded an ultrafast movie of the photon-to-electricity conversion process in pentacene, a molecular material that shows conversion of one photon into four charges, instead of the usual two. This excitation doubling, called exciton fission, could be extremely useful for high-efficiency photovoltaics. The researchers used time- and angle-resolved photoemission spectroscopy to observe the dynamics of electrons on the femtosecond time scale, which is a billionth of a millionth of a second, and captured images of the fleeting excited electrons for the first time. They identified the mechanism of the free charge carrier-doubling process, which is crucial for the use of organic semiconductors in innovative photovoltaic applications and to further boost the conversion efficiency of today's solar-cells.