Optical cooling in Semiconductor

 

Cooling systems are an integral part of many modern technologies, as heat tends to wear down materials and decrease performance in several ways. Efforts to achieve optical cooling in semiconductors have encountered several difficulties, primarily due to challenges in reaching nearly 100% emission efficiency, and true cooling has been elusive.

Solid-state optical cooling is a prominent example that leverages a very unique phenomenon called anti-Stokes (AS) emission. Usually, when materials absorb photons from incoming light, their electrons transition into an "excited" state. In materials that undergo AS emission, electrons interact with crystal lattice vibrations called "phonons" in such a way that the photons emitted are of higher energy than those in the incident light. If AS emission efficiency is close to 100%, these materials could theoretically cool down, rather than heating up, upon exposure to light.

Unfortunately, at low intensities, optical cooling becomes less effective. Under the best conditions, their sample demonstrated a theoretical cooling limit of approximately 10 K from room temperature.

Efforts to achieve optical cooling in semiconductors have encountered several difficulties, primarily due to challenges in reaching nearly 100% emission efficiency, and true cooling has been elusive.

If optical cooling improves significantly to reach widespread practical use, it could become the foundation of several energy-saving technologies, contributing to global sustainability goals.