UCLA engineers have unveiled a novel solid-state thermal transistor capable of rapidly switching heat flows on and off using an electric field—a long-sought innovation that could usher in a new era of advanced heat management technologies.
The research team’s room-temperature thermal transistor demonstrated record-high speeds, switching cycles, and heat flow control range by manipulating charge transport and chemical bonding forces. With the ability to modulate semiconductor device heat flows over a million times per second, the thermal transistors could enable transformative thermal management capabilities. This could mitigate overheating and boost the performance limits of computer chips and other electronics.
Looking beyond applications in computing, the researchers suggest the thermal switching concept may also provide new scientific insights into heat regulation in biological organisms at the cellular level.
How the High-Speed Thermal Transistor Works
The thermal transistor consists of a gold base layer coated with a mono-layer of specialized “carboranethiol” molecules that stand upright and link to a top graphene layer. The interface between the molecular layer and the gold substrate forms the critical foundation for thermal resistance and switching.
An electric field to a gate terminal controls the thermal transistor’s operation. Researchers can shift bonding charge distributions and electronic structure at the gold-molecule junction by tuning the field strength. This, in turn, modulates interfacial thermal transport phenomena such as phonon scattering processes and electron-phonon interactions—determining how much heat conducts from the gold substrate through the molecular layer.
The interface bonding manipulation approach enables fast switching speeds, cycles, and range improvements compared to existing thermal conductivity tuning methods reliant on slower molecular motions or deformations. Unlike past prototypes requiring fluid components, microelectromechanical systems, or exotic materials, the team’s design focuses on basic surface science principles applied at accessible solid-state interfaces.
The thermal transistor exhibits impressive performance metrics due to how the team configured its’ components and fundamental operating concept. In testing, the thermal switches toggled heat flows at frequencies over 1 megahertz across a thermal conductance range spanning 1,300 per cent. This represents orders of magnitude faster speeds than demonstrated in past experimental thermal transistors and an extensive control range at room temperature.
When cycled millions of times, the graphene-molecule-gold interfaces showed minimal performance degradation—attractive reliability for any prospective applications demanding frequent and reliable thermal switching.
A solid-state thermal switch like this, with practical room temperature application, opens exciting possibilities across disciplines. As electronics, meta devices, and other technologies push efficiency boundaries, thermal management presents a growing challenge. By enabling rapid, widely tunable heat flow control, the thermal transistors could equip computer chips to channel heat away from vulnerable hotspots without bulky cooling systems hampering processing speeds.
On a more exploratory level, as hinted at by the UCLA researchers, the thermal switching concept might also inspire biological studies. The heat flow control principles could provide insights into nature’s design of thermal regulation across scales of organization—from proteins to tissues to whole organisms. Mastering control over heating and cooling drives discovery.
Though future work remains in specialized integration within target systems, the team’s thermal transistor foundations and exceptional performance metrics spotlight promising directions. Ongoing advances in mapping interfacial heat transport phenomena to charge carrier dynamics and bonding interactions may uncover further heat switch optimization techniques. As thermal needs evolve amid society’s sustainability and computing ambitions, the capability to actively tune thermal conductivity over nanosecond-scale switching cycles will only increase in value across technology sectors.
Published as Electrically gated molecular thermal switch
- UCLA engineers developed a thermal transistor to switch heat flows using an electric field rapidly
- Solid-state device modulates thermal resistance at gold-molecule-graphene interface
- Achieved speeds over 1 MHz with 1,300% tuning range and 1M+ switching cycles
- Could enable advanced chip heat management and provide biological insights