Show me your true colours – micro-LEDs light the way to a world of flexible displays

Show me your true colours – micro-LEDs light the way to a world of flexible displays

This year’s Consumer Electronics Show in Las Vegas wowed the world with some truly inspirational technology. And it offered a glimpse of the great screen transformations yet to come.

A BMW car which changes colour at the flick of a switch was one of the most striking innovations revealed at CES 2023 in January. The BMW iX Flow uses electronic ink technology to turn the car’s exterior into 32 different hues on 240 panel segments. A gimmick at present, the ability of the car’s exterior to quickly cycle through a variety of shades may one day have real-world applications. There could be military uses of the technology allowing battlefield hardware to blend in with the surrounding scenery.

The great thing about CES is that it offers a top line view every year of the emerging technology set to change the world. And this year, the show didn’t disappoint, with everything from laptops offering 3D vision to the latest experiences in TV and gaming screens.

Each year, new improvements in mini-LED and micro-LED screen technology are unveiled. These screens are close to rivalling the high quality of OLED screens, whether in TVs, monitors, laptops or smartphones. The showdown between OLED and LED-powered screens has been one of the great display battles of the past decade.

While traditional Liquid Crystal Display (LCD) screens use an array of LEDs as a backlight to shine through the crystals, mini-LED expands the quality of LCD screens with an array of thousands of tiny LEDs. An even more miniature version is micro-LED with a yet greater number of small LEDs. These technologies allow LCD screens to have a hugely enhanced clarity and brightness rivalling OLED but at a much lower price. Mini-LEDs allow small areas of the screen to be dimmed by switching off the LEDs in that section. This is known as full array local dimming and is a significant upgrade on previous LCDs backlit by standard LEDs.

In the world of the future, displays will need to be put in places where they have never been placed before. There’ll be displays on car dashboards, on consumer appliances and white goods, and in novel and different shapes and sizes. As the notion of the Internet of Things takes off, screens will appear all around us.

But for screen ubiquity to progress, there will have to be some big improvements. Today’s displays are usually rigid and rectangular. Whether LCD or OLED, they are built on glass or hard plastic substrates. But what if you want a round display that resembles a clock? To get different shaped screens, manufacturers tend to cheat. Round displays are simply square displays with a circular bezel around them and content is only shown in the middle. The technology for making a round display is difficult.

So what happens if you want a display that goes on the dashboard of a car while blending in with interior and conforming to its surroundings? Such uses will increase with the development of electric and autonomous vehicles. But traditional LCD screens are unsuited to the needs of flexible displays.

Instead, flexible displays will require screens powered by mini-LEDs and micro-LEDs. SmartKem’s low-temperature TRUFLEX technology is ideally suited to aiding these developments.

Micro-LEDs are made by a process which involves growing them on wafers. They are then removed from the wafer and put on a substrate on top of a layer of transistors. SmartKem’s technology does away with the need to lift the micro-LEDs on to the transistor layer, an expensive and complex operations. Instead, organic thin film transistors (OTFTs) can be overlaid on the micro-LEDs after they have been grown. This hasn’t been possible until now because technologies for superimposing OTFTs requires high temperatures of 300 to 400 degrees centigrade. Such high temperatures would quickly destroy the LEDs. SmartKem’s TRUFLEX technology operates at 80 degrees centigrade, temperatures which do not damage micro- and mini- LEDs. So the OTFTs can be laid on top of the LED layer, making the whole process cheaper and easier. And one of the great advantages is that the LED layers can be created on flexible substrates rather than requiring hard plastic or glass. Think of micro-LEDs as bubble wrap, a sheet with thousands of bubbles where each bubble is an LED, but they are so small that you can barely see them. And you can shape the bubble wrap into any form you wish – which you cannot do with a sheet of glass.

This opens the way for flexible displays to be extended to vehicles, objects and furniture in a variety of shapes and sizes. SmartKem has already demonstrated samples of displays made using TRUFLEX technology. While these developments are at an early stage, within a few years, CES is likely to be showcasing more of these types of display innovations.

An area where mini and micro-LED displays could also have a transformative effect is on large area signage. Large displays on central city storefronts, on the tops of buildings or in sports arenas are constructed from standard-sized LEDs. But if you get within ten feet of the displays, you come too close to see the image and only notice the individual bulbs of the LEDs. Such screens have been less successful for indoor locations such as shopping centres and indoor sports because people get too close. But once these screens are built using mini- and micro-LEDs, they will allow viewers to stand in closer proximity and will become more common in smaller venues.

When it comes to colour-changing vehicles, micro-LED solutions could provide a powerful solution. On its colour-changing car, BMW uses colour shifting ePaper display technology, as used in e-readers. This deploys microscopic capsules containing different coloured powders. Millions of these capsules are sandwiched between plastic sheets. When an electric charge is applied to the capsules, the different coloured powders rise to the top of the capsules according to the size of the voltage and combine to create different shades. But this technology struggles to create deep and authentic colours. Micro-LEDs, by contrast, could be embedded in a plastic sheet and wrapped around sections of a car, a drone or a tank, and would have the ability to reflect true and clear colours. The prospect of colour-changing clothes, vehicles or camouflage is on the cards using the flexible substrates enabled by micro and mini-LEDs.

Every year CES impresses spectators with the latest advances in screen technology. Future shows will unveil the displays that are destined to revolutionise our world.