The Green Optimistic

Do you know that electrons can be “cooled”? The cooling of an electron, in lay language, is the transitory state in which the electron passes from a high-oscillation state to a low-oscillation, normal state. The high oscillation state is given by an external stimulus, i.e. electric voltage.

Scientists from the University of Chicago have obtained a slower electron cooling time in the nanocrystals of semiconductors (the ones your computer’s chips are made of). They obtained that by forcing them into a smaller volume. This has positive effects on laser production, “Slowing down the cooling of these electrons—in this case, by more than 30 times—could lead to a better infrared laser source,” said Philippe Guyot-Sionnest, Professor of Chemistry and Physics at the University of Chicago. “This, in turn, could be used to increase the bandwidth of communication satellites, allowing for faster connections.”

Beside that, photovoltaic cells could also benefit from this slowed electron cooling time, because most of them are made of semiconductors. Mr. Guyot-Sionnest also said: “This is because proposals to devise ways to extract the excess heat from these electrons as they cool are more likely to be realized—and to work—due to the fact that we now understand better what is going on with these nanocrystals.”

But, why does this happen? The scientists were able to slow the electron cooling in the nanocrystals because they forced the electrons in a smaller volume, so they oscillated between their their alternate extremes at very high frequencies. The electrons in the nanocrystals used in this experiment oscillated so fast that it became difficult for them to drag along the more sluggish vibrations of the nuclei. As a result, the energy stayed with the electrons for a longer period of time.

This phenomenon was observed back in 1990, but nobody observed this effect until now.

Though, as photovoltaic cells’ market begins to grow, more advanced methods of making them also appear. It seems that silicon crystals are slowly replaced by other technologies. This discovery could make them once again a viable alternative in the competition for gathering more solar power.