Scientists in China have created a new type of display with the smallest pixels and the highest pixel density ever. Individual pixels were shrunk to 90 nanometers – about the size of a virus – and a record 127,000 of them were crammed into every inch of a display.
The new display tech is based on light-emitting diodes (LEDs), which make up the commercial displays with the smallest pixels and highest pixel density currently available. The most advanced of these are called micro-LED displays, which boast, as the name suggests, pixels on the scale of micrometers.
The problem is, micro-LED displays are expensive, and when the pixels are shrunk smaller than about 10 micrometers, the display begins to lose efficiency. For the new study, scientists at Zhejiang University and the University of Cambridge built much smaller LEDs, with pixels down to the nanoscale, using a different semiconductor material.
Micro-LEDs are usually based on what are called III-V semiconductors – essentially, alloys made of elements from group III and group V of the periodic table. The team swapped these alloys for perovskite materials instead, which are known for their efficiency and affordability in next-gen solar cells.
The resulting perovskite LEDs (PeLEDs) were made in a range of sizes, including the smallest ever pixels measuring just 90 nanometers wide – that’s within the size range of viruses, and even on the small side of that range. Being so small, it’s no surprise that the researchers were also able to squeeze more of them into an array, managing a record-breaking density of 127,000 pixels per inch (PPI).
For comparison, one of the current leading consumer devices sporting a micro-LED display is the Apple Vision Pro headset. Each of its pixels measures 7,500 nanometers wide – about the size of a human red blood cell – and packs a density of around 3,386 PPI.
The PeLEDs also exhibited a much higher efficiency than other micro-LED systems. At pixel sizes between 3.5 and 650 micrometers, they consistently hovered around 20% efficiency, where most III-V micro-LEDs would drop sharply to less than half that rate at that size. Meanwhile, even the tiniest pixels managed around 10% efficiency, on par with other LED pixels 100 times their size.
The breakthrough didn’t just come from the material alone: the researchers had to develop a new way to etch structures into it. It’s usually done with lasers but that would damage the perovskite, so the team instead carved a lattice into the tougher materials that make up the top and bottom electrical contacts. This formed the pixels out of perovskite in the spaces.
The researchers now plan to explore how to make circuits small and detailed enough to convert the tech into useful display systems.
The research was published in the journal Nature.
Source: Zhejiang University
