Researchers develop solid-state thermal transistor for better heat management

I'm really excited to see progress being made in this area! I haven't read the paper but looked into this area about 10 years ago, and the two questions that jump to top of mind are:

1) What thermal transfer mechanism being controlled?

2) What is the dynamic range in terms of conductance? (Looks like 13x)

There are a number of different mechanisms for energy transfer at this level, and it seemed like the most straightforward way to build a thermal transistor was to get a material that was an insulator for all but 1 transfer mechanism (usually phonons) and then use an electric field to try to permit/block that. The solutions that did exist back then seemed to be very leaky, with thermal transfer while "on" was only about 3x that of when it was off, and this was for microscopic structures where it wasn't obvious how they would physically scale to useful sizes.

I would _love_ a practical thermal transistor technology for an energy management system in a passive house. Allowing your house to "breathe" at night during the summer without things like loud attic fans would be fantastic.

"Electrically gated molecular thermal switch" (2023) https://www.science.org/doi/10.1126/science.abo4297 :

> Abstract: Controlling heat flow is a key challenge for applications ranging from thermal management in electronics to energy systems, industrial processing, and thermal therapy. However, progress has generally been limited by slow response times and low tunability in thermal conductance. In this work, we demonstrate an electronically gated solid-state thermal switch using self-assembled molecular junctions to achieve excellent performance at room temperature. In this three-terminal device, heat flow is continuously and reversibly modulated by an electric field through carefully controlled chemical bonding and charge distributions within the molecular interface. The devices have ultrahigh switching speeds above 1 megahertz, have on/off ratios in thermal conductance greater than 1300%, and can be switched more than 1 million times. We anticipate that these advances will generate opportunities in molecular engineering for thermal management systems and thermal circuit design.

From "First Law of Thermodynamics Breakthrough Upends Equilibrium Theory in Physics" https://news.ycombinator.com/item?id=34967195 ::

> - "Thermodynamics of Computation Wiki" https://news.ycombinator.com/item?id=18146854