If you’re reading this on a screen, it’s likely you’re literally staring at the future.

Present in most LED screens, as well as the LED lights that now provide much indoor illumination, is the metal gallium. And while not as well known as silicon, it is taking over in many of the places that silicon once reigned supreme—from antennas to charging bricks and other energy-converting systems known as “power electronics.” In the process, it’s enabling a surprising array of new technologies, from faster-charging cellphones, to lighter electric vehicles, to more power-efficient data centers that run the services and apps we use.

A byproduct of extracting aluminum from rock, gallium has such a low melting temperature that it turns into a runny, silvery-white liquid when you hold it in your hand. On its own, it isn’t terribly useful. Combine it with nitrogen, to make gallium nitride, and it becomes a hard crystal with valuable properties. It shows up in laser sensors used in many self-driving cars, antennas that enable today’s fast cellular wireless networks, and, increasingly, in electronics critical to making renewable-energy harvesting more efficient.

Many of the most tangible things made possible by gallium nitride, also known as GaN, are happening in power electronics. Today, you can buy small USB-C chargers with enough juice to power your laptop, phone and tablet simultaneously, even though they are no bigger than the much less powerful versions that have for years come with our gadgets.

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Power electronics that convert one voltage level to another also are key to many aspects of electric vehicles. They are smaller, lighter, more efficient and emit less heat, so EVs can travel farther on a charge, says Jim Witham, chief executive of chip maker GaN Systems. Those properties also are great at squeezing significantly more electricity out of renewable energy sources such as solar panels, he adds. Even small efficiency gains in converting electricity add up when they happen multiple times, as in a renewable-powered grid that includes battery storage.

Miracle material that GaN may be, it faces competition from tried and true silicon and a growing list of new materials that show potential to revolutionize our electronics. Still, its uses are expanding. GaN Systems also has customers testing its chips in data centers, where reducing power consumption and waste heat can translate into massive savings on electric bills. None of its data-center customers have publicly acknowledged using the technology.

There was a time, not so long ago, that GaN was a mere laboratory curiosity. Then the Pentagon got interested, hunting for new kinds of electronics to drive next-generation radars and wireless communications. Beginning around 2000, funding from Darpa, the Defense Department’s advanced research agency, drove the experimentation required to overcome many of the hurdles to its commercialization, says Rachel Oliver, a professor of materials science and director of the Centre for Gallium Nitride at Cambridge University.

Alongside its myriad applications in the civilian world, GaN now shows up in military hardware used for everything from radio jamming to missile defense, all made possible by its unique properties.

In contrast to silicon, GaN can handle relatively large amounts of electricity. It has the unusual property of being both very good at moving electrons about and very good at not allowing them to go where you wouldn’t want them to be, which makes it both useful and relatively safe, says Dr. Oliver.

Gallium’s metal form; unusual properties of a crystalline compound, gallium nitride, make it useful in a range of advanced electronics.

Gallium’s metal form; unusual properties of a crystalline compound, gallium nitride, make it useful in a range of advanced electronics.

Photo: Gabriel Zimmer for The Wall Street Journal

Along with its talent for conducting electricity, it’s GaN’s ability to operate at frequencies that are much higher than possible with silicon—between 30 and 500 times as fast in commercial applications—that enable chargers that are much smaller or deliver more power than traditional ones.

As our entire world becomes more and more electrified, from our sources of energy to the devices that use it, anything that more efficiently performs the critical but easy-to-overlook function of converting electricity from one form to another has the potential to become both ubiquitous and an enormous source of revenue. That’s why there are dozens of startups and established companies in this space, including Navitas Semiconductor, GaN Systems, Power Integrations, Texas Instruments, Infineon and STMicroelectronics.

The market for GaN power electronics is still quite nascent, however. In 2019, the entire market for all transistors was about $16 billion, whereas the market for the kind offered by Navitas, GaN Systems and others was $45 million, says George Brocklehurst, a vice president of research at Gartner.

There are other potentially revolutionary materials that are beginning to compete with silicon, like graphene, but GaN microchips have the considerable advantage that they can be produced in the same sort of manufacturing facilities—called fabs—that make conventional microchips, says Stephen Oliver, head of marketing at Navitas.

“ Toyota recently showed off a prototype vehicle loaded with gallium nitride-based electronics. ”

Because they don’t require the most advanced chip-manufacturing technology, GaN chips can be produced in older, paid-for fabs that might otherwise be idled. A fortunate side effect has been that GaN chip supply hasn’t been caught up in the wider global semiconductor shortage, says Mr. Oliver. Navitas’s chips are currently manufactured in the oldest fab still operated by TSMC, the Taiwanese chip-manufacturing titan.

GaN uptake is now becoming so widespread that prices are rapidly falling. That’s why you can now buy a GaN charger for $20 to $70 that is better in every way than the ones that came with your gadgets.

Companies like GaN Systems are pushing the technology into other areas. Both BMW and Toyota are investors in GaN Systems. In 2019, Toyota showed off a prototype vehicle with entirely GaN-based power electronics, from the car’s onboard charger to its LED lights.

That said, GaN chips aren’t a slam-dunk winner. Advances in materials science have generated a handful of competitors. Traditional silicon power electronics are still dominant in most applications, and in the automotive world, silicon carbide, an alternative with many of the same properties as GaN, has a much longer track record, says Gartner’s Mr. Brocklehurst.

An array of promising but less well-understood substances could give all of the previously mentioned ones a run for their money, including gallium oxide and aluminum oxide. Both are semiconductors that can be patterned into microchips, says Dr. Oliver.

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Where the material revolution hasn’t taken hold is in the biggest market for semiconductors: the processors powering our computers. Until recently, Dr. Oliver says, GaN has been good at doing only half the things that a traditional silicon transistor can do.

So far, GaN can’t handle the electric-current flows needed to run the kind of computations carried out by traditional silicon logic chips. But recent findings suggest that may be changing.

“If you’d asked me a few years ago if we’d see GaN for logic, I’d say: ‘Oh, don’t be stupid,’ ” she says. “But now it’s possible, and it may lead to faster devices.”

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Write to Christopher Mims at christopher.mims@wsj.com