Transistors are considered one of the 20th century’s greatest inventions because they are a key component of most modern electronics. The first working version was a point-contact transistor invented by physicists John Bardeen, Walter Brattain, and William Shockley in 1947 at Bell Labs. The three physicists shared the Nobel Prize in Physics for this achievement in 1956.
Thirty years later, in 1986, researchers H. Koezuka, A. Tsumura, and Tsuneya Ando at Mitsubishi Electric invented organic thin-film transistors (OTFT) technology based on a thiophene polymer semiconductor material.
Organic thin film transistors became the foundation for flexible integrated circuits and displays.
Display evolution
Industry-breaking low temperatures mean organic thin film transistors can be poured onto a MicroLED display
In 2007 Sony reported the first full-color, video-rate, flexible, all plastic display that both the thin-film transistors and the light-emitting pixels were made of organic materials.
“Sony’s 2007 display was a flexible OLED display that was never taken into production or commercialized,” said Ian Jenks, CEO of Smartkem. “This is because their transistors were not of a high enough quality or performance to produce a manufacturable display, even for an OLED.”
“The whole of the display industry is moving twards microLED solutions,” said Jenks. “LCDs are still the biggest player, then came long OLED displays, and now MicroLEDs.”
“The display industry is ready for disruption,” said Jenks.
“All displays, whether for a watch, a phone, or a TV screen are built of two things: a piece at the front that glows (white, red, green, blue, OLED / MicroLED), and a sheet of transistors at the back,” said Jenks. “It doesn’t matter what the display is, you need transistors to drive it.”
In September 2024, Smartkem announced at the MicroLED Connect conference that it had the potential to power the next generation of displays using its organic thin-film transistors. But the competitive difference was that Smartkem’s OTFTs were processed at ultra-low temperatures—at 80 degrees Celsius versus the industry standard of 300 degrees Celsius. The result is OTFTs that can be poured onto a MicroLED.
In late November 2024, the company announced a partnership with AUO, Taiwan’s largest display manufacturer, to jointly develop the world’s first advanced rollable, transparent microLED display using Smartkem’s technology.
The Smartkem and AUO MicroLED project begins Q1 2025. The collaboration received a grant from the 2024 Taiwan-UK Research & Development Collaboration, which is supported by The Taiwanese Ministry of Economic Affairs and Innovate UK, which is part of UK Research and Innovation (UKRI).
The next generation of displays
Rollable MicroLED displays in the form of a roller blind
“The problem that microLEDs have, is that they’re very, very small,” said Jenks. “Whilst they may be the same things you find in lightbulbs, the ones you need for TVs are 1/20,000th of the size.”
“But in a 40-inch TV, you’ll have 25 million of them,” said Jenks. “To make the display, you need to find a way of connecting those 25 million MicroLEDs to 25 million transistors, and that’s really difficult to do with any of the transistor technologies that exist today.”
Jenks says if you’re introducing a new technology, you want something that can’t be done another way.
For Smartkem, that means displays on lightweight, transparent plastics.
“That gives you access to a whole bunch of new form factors including rollable displays, where your TV can be like a roller blind, through to sheets of plastic where you can stick them to a glass window and have them advertising and communicating,” said Jenks. “At the same time, you would be able to see through them, i.e., in a shop window or a car window.”
Jenks adds that pourable OTFT transistors on a plastic substrate hold the prospect of being able to put transistors on biodegradable plastics in the future.
A clear path to the MicroLED market
Chip-first display architecture changes the manufacturing landscape
Smartkem believes it is poised to transform the display industry with this new class of MicroLED displays.
Jenks says their low-temperature approach enables the processing of Smartkem’s OTFTs on a plastic substrate rather than glass, which offers the market the advantage of being low-cost, thin, transparent, flexible, and lightweight.
According to a media statement, processing directly on top of microLEDs in the manufacturing process eliminates the need for mass transfer and laser welding processes required by existing technology. The company say this process introduces an entirely new chip-first display architecture to the display market that’s not currently possible using other transistor technologies.
The technology will run on the Industrial Technology Research Institute’s (ITRI) Gen 2.5 assembly line.
“ITRI is the gold standard of transistor manufacturing processes in the world,” said Jenks. “Having AUO as the route to market, ITRI is working with us on the process development, and our new transistors are the best ecosystem to take our technology to market.”