‘World’s smallest LEDs’ could lead to accurately lit screens with 127,000 pixels per inch and much more immersive VR

Sometimes small is actually big—at least when it comes to advancements in LED technology. For a bright, clear picture, OLED screens are where it’s at; they easily outperform traditional LED displays and have breathtaking Micro-LED displays beat when it comes to price—though that’s not hard to do when a reasonably sized Micro-LED screen can easily cost thousands of dollars still. We all love a screen that boasts accurate backlighting, but not that much.

Researchers at Zhejiang University and Cambridge University have unveiled LED display technology that’s even smaller and potentially a darn sight more efficient. In a blog post, it was announced the team had created not just micro-LEDs but nano-LEDs featuring “pixel lengths of 90 nanometers” (via Tom’s Hardware). These make them not only the smallest LEDs in the world but also mean screens of the future leveraging this tech could potentially cram in an astonishing 127,000 pixels per inch.

To put that into perspective, a 27-inch 4K gaming monitor has just a piffling 163 pixels per inch. Even if you start counting the individual sub-pixels, one for each colour channel, you’re still getting less than 1,000 per inch.

So, what’s the secret sauce of these teeny tiny LEDs? Perovskite, a mineral most commonly used in solar panels (not unlike this wacky solar-powered laptop from Lenovo). As such, the researchers refer to their itty bitty, Perovskite-based LEDs as “nano-PeLEDs,” and they claim that “unlike the conventional micro-LEDs based on III-V semiconductors, the micro/nano-PeLEDs exhibit minimum performance reduction upon downsizing.” Talk about small but mighty.

Developing these nano-PeLEDs was hardly straightforward though, as Perovskite tends to be too fragile to withstand the photolithographic processes usually required to create LED displays. To put it very simply, the researchers instead deployed a bespoke process that deploys “lithographically patterned windows in an additional insulating layer” to protect the Perovskite in a way that also doesn’t compromise image quality. For a much longer answer, the team wrote at length about the process in an article recently published in the scientific journal Nature.

When discussing the future of this technology, gaming does get an explicit mention from the team. To briefly rewind, Micro-LEDs are a compelling option for VR headsets despite their expense. However, to complete the illusion of virtual reality, you need a screen that can produce an image that holds up to scrutiny at blinking distance.

Unfortunately, the efficiency of a Micro-LED display taps out when you really try to hide the seams between pixels by making them much smaller. For the time being, LCD and micro-OLED displays rule the VR roost, but Nano-PeLEDs could instead succeed where Micro-LEDs have so far failed.

Professor Zhao Baodan of Zhejiang University muses in the blog post, “The efficiency of micro-LEDs drops rapidly when the pixel sizes are smaller than 10 micrometers, which are the desirable pixel sizes for high-end [virtual reality] applications with ultra-high resolutions. Halide perovskites are a new class of semiconductors. It would be interesting to see how perovskite LEDs perform when they are made extremely small.”

Virtual reality dreams aside for now, the team have partnered with LinkZill, a Hangzhou-based company specialising in thin-film transistor tech, in order to jointly create “a prototypical active-matrix micro-PeLED display driven by a [thin-film transistor] backplane.” This prototype is likely the first step towards more widespread commercial uptake of micro- and nano-PeLED tech…so you could say, the future looks bright. And very, very small.