flexible display screens ready for mass production factory

Our sheet-to-sheet screen printing process enables rapid prototyping with great flexibility. Multiple display design options can be manufactured simultaneously at no additional cost, provided they fit in the same printing toolset. We will provide support throughout the entire prototyping process with design for mass production in mind.

Kateeva’s YIELDjet system (pictured here) is a massive version of an inkjet printer. Large glass or plastic substrate sheets are placed on a long, wide platform. A head with custom nozzles moves back and forth, across the substrate, coating it with OLED and other materials.

Based on years of Institute research, MIT spinout Kateeva has developed an “inkjet printing” system that could cut manufacturing costs enough to pave the way for mass-producing flexible and large-screen OLED displays.

Flexible smartphones and color-saturated television displays were some highlights at this year’s Consumer Electronics Showcase, held in January in Las Vegas.

Many of those displays were made using organic light-emitting diodes, or OLEDs — semiconducting films about 100 nanometers thick, made of organic compounds and sandwiched between two electrodes, that emit light in response to electricity. This allows each individual pixel of an OLED screen to emit red, green, and blue, without a backlight, to produce more saturated color and use less energy. The film can also be coated onto flexible, plastic substrates.

But there’s a reason why these darlings of the showroom are not readily available on shelves: They’re not very cost-effective to make en masse. Now, MIT spinout Kateeva has developed an “inkjet printing” system for OLED displays — based on years of Institute research — that could cut manufacturing costs enough to pave the way for mass-producing flexible and large-screen models.

In doing so, Kateeva aims to “fix the last ‘Achilles’ heel’ of the OLED-display industry — which is manufacturing,” says Kateeva co-founder and scientific advisor Vladimir Bulovic, the Fariborz Maseeh Professor of Emerging Technology, who co-invented the technology.

Called YIELDjet, Kateeva’s technology platform is a massive version of an inkjet printer. Large glass or plastic substrate sheets are placed on a long, wide platform. A component with custom nozzles moves rapidly, back and forth, across the substrate, coating it with OLED and other materials — much as a printer drops ink onto paper.

An OLED production line consists of many processes, but Kateeva has developed tools for two specific areas — each using the YIELDjet platform. The first tool, called YIELDjet FLEX, was engineered to enable thin-film encapsulation (TFE). TFE is the process that gives thinness and flexibility to OLED devices; Kateeva hopes flexible displays produced by YIELDjet FLEX will hit the shelves by the end of the year.

The second tool, which will debut later this year, aims to cut costs and defects associated with patterning OLED materials onto substrates, in order to make producing 55-inch screens easier.

By boosting yields, as well as speeding up production, reducing materials, and reducing maintenance time, the system aims to cut manufacturing costs by about 50 percent, says Kateeva co-founder and CEO Conor Madigan SM ’02 PhD ’06. “That combination of improving the speed, improving the yield, and improving the maintenance is what mass-production manufacturers want. Plus, the system is scalable, which is really important as the display industry shifts to larger substrate sizes,” he says.

Traditional TFE processing methods enclose the substrate in a vacuum chamber, where a vapor of the encapsulating film is sprayed onto the substrate through a metal stencil. This process is slow and expensive — primarily because of wasted material — and requires stopping the machine frequently for cleaning. There are also issues with defects, as the coating that hits the chamber walls and stencil can potentially flake off and fall onto the substrate in between adding layers.

But moisture, and even some air particles, can sneak into the chamber, which is deadly to OLEDs: When electricity hits OLEDs contaminated with water and air particles, the resulting chemical reactions reduce the OLEDs’ quality and lifespan. Any displays contaminated during manufacturing are discarded and, to make up for lost yield, companies boost retail prices. Only two companies now sell OLED television displays, with 55-inch models selling for $3,000 to $4,000 — about $1,000 to $3,000 more than their 55-inch LCD and LED counterparts.

YIELDjet FLEX aims to solve many TFE issues. A key innovation is encasing the printer in a nitrogen chamber, cutting exposure to oxygen and moisture, as well as cutting contamination with particles — notorious for diminishing OLED yields — by 10 times over current methods that use vacuum chambers. “Low-particle nitrogen is the best low-cost, inert environment you can use for OLED manufacturing,” Madigan says.

In its TFE process, the YIELDjet precisely coats organic films over the display area as part of the TFE structure. The organic layer flattens and smoothes the surface to provide ideal conditions for depositing the subsequent layers in the TFE structure. Depositing onto a smooth, clean surface dramatically improves the quality of the TFE structure, enabling high yields and reliability, even after repeated flexing and bending, Madigan says.

Kateeva’s other system offers an improvement over the traditional vacuum thermal evaporation (VTE) technique — usually somewhere in the middle of the production line — that uses shadow masks (thin metal squares with stenciled patterns) to drop red, green, and blue OLED materials onto a substrate.

This isn’t necessarily bad for making small, smartphone screens: “If a substrate sheet with, say, 100 small displays on its surface has five defects, you may toss five, and all the rest are perfect,” Madigan explains. And smaller shadow masks are more reliable.

But manufacturers start to lose money when they’re tossing one or two large-screen displays due to particle contamination or defects across the substrate.

Kateeva’s system, which, like its TFE system, is enclosed in a nitrogen chamber, precisely positions substrates — large enough for six 55-inch displays — beneath print heads, which contain hundreds of nozzles. These nozzles are tuned to deposit tiny droplets of OLED material in exact locations to create the display’s pixels. “Doing this over three layers removes the need for shadow masks at larger scales,” Madigan says.

As with its YIELDjet FLEX system, Madigan says this YIELDjet product for OLED TV displays can help manufacturers save more than 50 percent over traditional methods. In January, Kateeva partnered with Sumitomo, a leading OLED-materials supplier, to further optimize the system for volume production.

The idea for Kateeva started in the early 2000s at MIT. Over several years, Madigan, Bulovic, Schmidt, Chen, and Leblanc had become involved in a partnership with Hewlett-Packard (HP) on a project to make printable electronics.

They had developed a variety of methods for manufacturing OLEDs — which Madigan had been studying since his undergraduate years at Princeton University. Other labs at that time were trying to make OLEDs more energy efficient, or colorful, or durable. “But we wanted to do something completely different that would revolutionize the industry, because that’s what we should be doing in a place like MIT,” Madigan says.

A few years before, Bulovic had cut his teeth in the startup scene with QD Vision — which is currently developing quantum-dot technology for LED television displays — and was able to connect the group with local venture capitalists.

Madigan, on the other hand, was sharpening his entrepreneurial skills at the MIT Sloan School of Management. Among other things, the Entrepreneurship Lab class introduced him to the nuts and bolts of startups, including customer acquisition and talking to investors. And Innovation Teams helped him study markets and design products for customer needs. “There was no handbook, but I benefitted a lot from those two classes,” he says.

So in 2012, Kateeva pivoted, switching gears to its YIELDjet system. Today, the system is a platform, Bulovic says, that, in the future, can be tweaked to print solid stage lighting panels, solar cells, nanostructure circuits, and luminescent concentrators, among other things. “All those would be enabled by the semiconductor printer Kateeva has been able to develop,” he says. “OLED displays are just the first application.”

Founded by a Stanford PhD graduate, Royole has designed and is starting to mass-produce a super-thin flexible screen that could be used in everything from t-shirts to portable speakers.

It"s the stuff of science fiction, and plenty of tech trade shows — a screen so thin and flexible that it can be rolled up into a cylinder as small as a cigarette or hung on a wall like wallpaper.

Royole just opened a new factory in China that is already mass producing the displays, and the company is working with partners to get them installed in everything from t-shirts to automobiles to smartphones.

Royole"s screens are based on OLED technology, in which the lighting elements are built into the display itself. Unlike the OLED screens that are in some higher-end televisions, which are typically placed on a rigid base like glass, the lighting elements in Royole"s screens are placed on a flexible plastic base, so they can bend or roll up.

"The cool thing here is that we"re not limited by the form factor of the surface," said Liu, who founded Royole with some friends from Stanford after graduating from there with a PhD in electrical engineering. "They could be anywhere."

Royole, which was founded in 2012 and has raised $1.1 billion in funding, just brought its new factory online in June. The plant will be able to produce up to 50 million panels a year once it"s at full capacity, Liu said. That could help it feed a potentially burgeoning market for bendable gadgets.

Researchers have been trying to develop flexible screen technology since at least the early 1970s — first in the form of monochrome displays that were intended to replace printed pages, and then, much later, in the form of color ones that might replace the screens in TV or portable devices.

For much of the last decade, display makers including Samsung and LG have been showing off their flexible OLED screens and prototype of products made with them at trade shows.

Samsung"s Galaxy Round, a relatively obscure smartphone that came out that year, was one of the first gadgets that used a flexible screen way back in 2013. Because the display was placed behind a fixed plate of glass, so you couldn"t really tell that it was bendable. The only clue was that the front of the phone was concave.

Other smartphones since the Galaxy Round have also employed flexible displays, including the LG G Flex and the Edge versions of the Samsung Galaxy S and Galaxy Note lines. More recently, the screens have started to make their way into even mainstream devices. Apple"s iPhone X, for example, has a flexible display behind its famously notched screen.

They were "a disappointing application of what that the technology could do," said Raymond Soneira, CEO of DisplayMate, a consulting firm for the display and TV industries.

Neither businesses nor consumers were ready for bendable or foldable gadgets when the first flexible displays started rolling off production lines five years ago, analysts said. Electronics makers generally hadn"t set up their supply chains to accommodate them or figured out how they might be able to take advantage of the screens" properties in new products. Apps hadn"t been written specifically for devices with bendable screens. And nobody had laid the groundwork for new kinds of flexible gadgets by marketing them to consumers.

Things may be different now. Next year, Samsung will reportedly introduce a phone with a foldable screen that"s built around its flexible display technology. Apple reportedly has a foldable phone in the works, too.

"You can"t make [phones] much bigger … and have them be carried by most consumers," Soneira said. "So you"ve got to move up to foldable, even rollable screens."

The release of foldable screen phones and other gadgets from major manufacturers will likely spur developers to start making apps designed specifically around those features. It"s also likely to inspire demand for other devices that take advantage of the properties of bendable screens.

Flexible screens will likely get their start by replacing other screens in devices we already recognize, including not just smartphones, but computer monitors and laptop computers, allowing manufacturers to make models that are slightly more innovative or resilient, said Ryan Martin, a principal analyst at ABI Research. But eventually, manufacturers are likely to get a lot more creative with them.

A flexible display "changes the realm of design as well as design thinking," Martin said. "You"re no longer confined to the four corners of a screen. You can make things more abstract."

At CES, the giant electronics trade show held in Las Vegas every January, LG has shown off a prototype for a car dashboard in which the speedometer, tachometer and other other gauges and buttons are displayed virtually on flexible screens that could be shaped to the contours of a car"s interior.

Although the company is going up against some of the biggest electronics companies around in LG and Samsung, Royole"s got several advantages, Liu said. Its displays are built on its own proprietary technology for which it has filed numerous patents, he said. That technology allows it to build screens that are a tenth as thick as those of competitors.

What"s more, because it"s using a different methodology for building its screens, it was able to get its factory up and running for about $1 billion, which is far less than what it would cost its competitors, he said.

The first devices with Royole"s screens should start showing up later this year. The company plans to sell T-shirts and hats with its flexible displays built in. Soon thereafter, it expects marketers to start using its screens to display advertisements in elevators, airports, shopping malls, and other places.

From there, the screens should start making its way into other products, both traditional and new, Liu said. When purchased in volume, they should be competitive in price to other types of displays, he said.

Ladies and gentlemen, our dreams of flexible digital newspapers are nearly within reach: LG just announced that it has begun mass production of a 6-inch, 1024 x 768 e-paper screen that can bend by up to 40 degrees. We haven"t been able to find a press release, but several Korean publications are reporting that the plastic-based screen is shipping to Chinese manufacturers to build e-readers right away, and devices based on the technology could be available in Europe as soon as early April. LG is boasting that at 0.7mm thick, the entire display is as thin as a protective film for a phone"s screen. According to the reports, LG conducted 1.5-meter (about 5 foot) drop tests with the screen and smacked it with a rubber mallet with no ill effect. We"re waiting for the other shoe (or e-reader) to drop, but that sounds positively fantastic. Maybe we"ll get some bendable batteries to go with the screen, some day.

(Phys.org)—Is Samsung getting ready to release a line of flexible displays made of glass-replacing plastic? The right words in response may be "well, finally," or "well, maybe." The Wall Street Journalhas talked to a source who said that Samsung, in the words of the WSJ subheading, "Plans to Mass Produce Flexible Mobile-Device Screens" in the first half of next year. The source was not named and was only described as "a person familiar with the situation." Samsung has tantalized techies and consumers with its futuristic videos showing a beautiful-life day using wearable wrist computers, auto dashboard display screens, location-finding smartphones, and wall mounted computer screens of plastic rather than glass.

Expectations are that Samsung, as part of the grand mix, is to start mass production of smartphone screens using bendable plastic rather than glass. According to the WSJ report, Samsung"s flexible displays will incorporate OLEDs.

Analysts believe the move into mass production would be a real business advantage as smart-device makers in competition with Samsung scramble for attention and market share with their designs and feature sets. Some of the reasons why a Samsung customer would favor plastic rather than conventional glass would be lightness and durability. As for Samsung, the technology could also help lower manufacturing costs as well as differentiate its products from rivals, said an analyst at Shinyoung Securities in the WSJ report.

Hopes that Samsung would not miss the 2012 mark in flex displays for television were shelved this year with reports of problems preventing release of the 55-inch OLED TVs. The idea had been to sell them in time for the London Olympics.

Samsung is considered one of the leaders in OLED display research and the leader in (Active Matrix) AMOLED, where a transistor next to each pixel brings faster response time. OLED Displays are thinner, more efficient and offer better picture quality than LCD or Plasma displays.

As for smartphones, back in March, analysts were already talking about how Samsung was looking at its plastic-backed AMOLED devices to make lightweight, ultra-thin phones with foldable screens. Analysts said they expected to see Samsung apply plastic substrate-based, bendable or curved displays for smartphones with the first products carrying a design where a screen is folded over the edges of a phone, so that the display continues on to the sides. The display would be unbreakable.

After years of talk about producing a foldable smartphone, Samsung will be ready to start mass production on the Infinity Flex display in the coming months, the company announced Wednesday at the Samsung Developer Conference in San Francisco.

The Infinity Flex display "is the foundation for the smartphone of tomorrow," Justin Denison, Samsung"s SVP of mobile product marketing, said during the keynote address. "It"s a blank canvas for us to do something beautiful together."

Denison gave the audience a taste of what Samsung"s highly-anticipated foldable phone will look like, holding up a device largely shrouded in darkness to disguise certain elements of design. The display was visible to reveal a cover display that is a fully-functioning touchscreen. A user can unfold the device to access a larger main display. If a user is running an app on the cover display, they can open the device to find the app "right there waiting," Denison said, demonstrating the continuity. The device will allow three apps to run simultaneously, Denison said.

To create the display, Samsung has replaced the glass cover window with an advanced composite polymer that"s both flexible and tough, Denison explained. Samsung is also using a malleable adhesive, he said, "making this new display flexible and durable enough to be folded hundreds of thousands of times." To make the display foldable, it"s also thinner than any mobile display Samsung has ever made, thanks to a new polarizer that"s 45 percent thinner.

In addition to producing the Infinity Flex, Denison said, "Our innovation pipeline includes new technologies such as rollable and even stretchable displays."

Samsung has for years talked about introducing a foldable phone, and in September of this year, Koh declared that it was finally "time to deliver." The Korean company teased the Infinity Flex announcement a few days earlier, when it changed its logo so that the name "Samsung" is folded over itself.

Engineers at the University of Toronto are the first Canadian team to construct flexible organic light emitting devices (FOLEDs), technology that could lay the groundwork for future generations of bendable television, computer and cellphone screens. "It opens up a whole new range of possibilities for the future," says Zheng-Hong Lu, a professor in U of T"s Department of Materials Science and Engineering. "Imagine a room with electronic wallpaper programmed to display a series of Van Gogh paintings, or a reusable electronic newspaper that could download and display the day"s news and be rolled up after use."

Today"s flat panel displays are made on heavy, inflexible glass that can break during transportation and installation. Lu, working with post-doctoral fellow Sijin Han and engineering science student Brian Fung, developed FOLEDs made on a variety of lightweight, flexible materials ranging from transparent plastic films to reflective metal foils that can bend or roll into any shape.

FOLED technology could be manufactured using a low-cost, high-efficiency mass production method, Lu says. The team, which is already commercializing some related technology, hopes a marketable device could be created within two to three years.

Their research was funded by the Canadian Foundation for Innovation, the Ontario Innovation Trust, the Premier"s Research Excellence Awards, Materials and Manufacturing Ontario, the Emerging Materials Network and the Ontario Research and Development Challenge Fund.

At OTI Lumionics we are developing advanced materials—by design—using quantum simulations, machine learning and real-world testing in pilot production. We are currently focused on key enabling materials for OLED displays that will be used in next-generation consumer electronics and automotive. Our advanced electrode materials, and associated manufacturing technology, are being used to build transparent displays and lighting.

We work closely with our partners and customers to design new materials that are mass-production ready. Using our computational Materials Discovery Platform, we are able to rapidly iterate new materials, allowing fast turn around time to meet our customers’ needs.

Korean media outlet Thelecreported on Monday that BOE, a Chinese electronic components firm, has recently converted the layout of its B12 OLED panel factory so that it can manufacture panels for IT products and automobiles, besides just smartphones. Rivals Samsung Display and LG Display are also at leading stages in the IT OLED panel technology field.

The phase three production line at the B12 facility in Chongqing, China will be able to manufacture OLED panels for smartphones, IT and automobiles. Phase three was initially designed to handle Gen 6 (1500x1850mm) flexible OLED panels for smartphones, as in phases one and two. The change of plan hints that BOE is likely aiming to supply OLED panels for Apple’s IT products, from tablets to PCs. The Chinese display giant has designed phase three of the B12 facility so that it can manufacture OLED panels of up to 15 inches in size, sources said.

BOE’s B12 factory started phase one operations last year during the fourth quarter; the second phase is expected to commence during the first half of this year. Equipment for phase three will enter installation in April.

On December 28, 2021, BOE’s official WeChat account showed that the company’s sixth-generation AMOLED (flexible) production line project in the southwestern city of Chongqing has now begun mass production.

This project further expands BOE’s flexible display technology reserves and production capacity and will round out the company’s link of flexible display production lines in Chengdu and Mianyang, two cities in nearby Sichuan Province.

At present, BOE has deployed six key projects in Chongqing, including the sixth-generation AMOLED (flexible) production line. It also has the 8.5-generation TFT-LCD production line, and the BOE Chongqing Smart System Innovation Center. These production lines have cumulative investment of over 86 billion yuan ($13.5 billion).

SINGAPORE/NEW YORK (Reuters) - The touted arrival this year of wearable gadgets such as computer displays strapped to wrists and in wrap-around glasses is just a step towards a bigger revolution in screens - those that can be bent, folded and rolled up.A Cima NanoTech employee uses a portable microscope to show their proprietary SANTE Technology silver nanoparticle network on a sample piece of SANTE Film laminated on glass in their lab in Singapore in this April 12, 2013 photo. The network on the SANTE Film enables electrical conductivity at high transparency and flexibility. REUTERS/Edgar Su

Once freed from today’s relatively heavy, breakable and fixed glass displays, tomorrow’s devices may look very different, with screens that can be rolled out, attached to uneven surfaces, or even stretched.

“It becomes a product designer’s paradise - once the technology is sorted out,” says Jonathan Melnick, who analyses display technology for Lux Research.

There is no shortage of prototypes - South Korea"s Samsung Electronicsthis year showed off a display screen that extends from the side of a device - but obstacles remain: overcoming technical issues, figuring out how to mass produce parts cheaply, and coming up with devices compelling enough for gadget buyers.

Screen technology - and the global small display market is seen more than doubling to around $72 billion by 2016, according to DisplaySearch - is still dominated by liquid crystal displays (LCDs), which require a backlight and sit between two sheets of glass, making the screen a major contributor to the weight of a device, from laptops to tablets.

"Most of the weight in a tablet is the glass structure in the display and the support structure around it to prevent it from cracking," said Kevin Morishige, a former engineer at Cisco Systems Inc, Hewlett-Packard Coand Palm.

LCD’s dominance is already under threat from lighter Organic Light Emitting Diodes (OLEDs) that don’t need backlighting, are brighter, offer a wider viewing angle and better colour contrast - and can be printed onto a few layers.

Corning Inc, whose toughened Gorilla glass became the screen of choice for many smartphones, will provide phones with curved glass edges as soon as this year. It is also now promoting Willow Glass, which can be as thin as a sheet of paper and is flexible enough to be wrapped around a device or structure. Initially, Willow will be used as a coating for products like solar panels, but it is eventually expected to create curved products.

A key selling point for Willow is more efficient production which involves so-called roll-to-roll manufacturing, like a printing press, rather than today’s more costly batch manufacturing. But the commercialization of Willow as a flexible product is some way off, James Clappin, who heads Corning’s glass technology group, told Reuters.

“You can bend it, but you can’t keep flexing it,” said Adrian Burden, a UK consultant who has worked on several start-ups related to display technology, and holds patents in the field. This means that while glass is likely to continue to play a leading role in devices with curved displays, screens that users can bend, fold and roll will likely be plastic.

“There are barrier films in all sorts of products, for example food packaging, but the challenge is that OLED is one of the most sensitive materials we follow, and so creates huge challenges,” says Lux Research’s Melnick.

Singapore-based Tera-Barrier Films, for example, has developed a way to plug leaks in the layers using nanoparticles. Director Senthil Ramadas says that after years of delays the company last month started production in Japan and aims for mass production by end-2014. “You have several challenges in the value chain,” he said. “All these things need to be established, and only now is it coming out.”

And there’s another problem: all the materials in a bendable display need to be bendable, too - including the transparent conductors that drive current through the display. Several technologies are vying to replace the brittle and expensive Indium Tin Oxide (ITO) used in most fixed displays, including nanowires, carbon nanotubes, graphene and conductive mesh.

Some of these technologies are close to production. Another Singapore-based firm, Cima Nanotech, for example, rolls a coating of silver-based conductive ink on a sheet which then self-aligns into a web of strands a few microns across that forms the conductive layer.

It’s unlikely such shifts in the underlying technologies will yield products immediately. For one thing, “prototypes can be made,” says Melnick, “but that’s a long way from mass production as many of the processes and material in these devices face big yield and scaling issues.”

This is gradually changing, some in the industry say, as production shifts from making parts in batches of sheets to the more efficient roll-to-roll process. “Batch is more expensive and slower than roll-to-roll, which needs new equipment and design - and takes time,” said Ramadas at Tera-Barrier.

Even after the success of Gorilla Glass, popularized by the Apple InciPhone, Corning is having to work hard to prepare customers for Willow displays. Clappin said customers want thinner devices and easier to produce glass, but Willow requires a completely different manufacturing set-up.

He sees demand, particularly from video gamers, for Willow-based curved screens, but remains less convinced about rollable or foldable screens. “Conformable is in the near future. As far as flexible, bendable, fold-upable goes, I see that further out and I’m not even sure that’s a viable product,” he said.

That in turn requires figuring out what end users might want. “For us and for our clients it’s not so much about the flexible display technology,” says Brandon Edwards, Shanghai-based executive creative director of frog, a design company owned by India’s Aricent. “That’s a huge part of it, but what are the practical ways we can bring products to market and how fast, and what’s the right cadence? What are consumers going to be responsive to?”

For companies with deep pockets, like Samsung, this can mean building prototypes such as those displayed at international technology shows. But that doesn"t guarantee success in selling products. Sony Corp, for example, promoted flexible OLED displays back in 2007. "Six years later they"ve not come up with anything," says Zhang Jie, senior scientist at Singapore"s Institute of Metals Research and Engineering. "If Samsung"s going to really drive this the application really needs to drive people and make them want it."

This slows down the process. In late 2011, Samsung told analysts it planned to introduce flexible displays into handsets “some time in 2012, hopefully the earlier part than later”, but a year later the company said the technology was still “under development.” In an investment note last month Jefferies said that while Samsung may introduce “unbreakable” screens this year, it didn’t expect to see flexible displays in Samsung devices until 2014-15.

“This is the eternal question of the speciality materials industry,” says Lutz Grubel, Japan-based head of marketing for German glass maker Schott’s Xensation Cover 3D glass. “You have something, a material, and you’re looking for an application. That’s the game.”

Engineers at the University of Toronto are the first Canadian team to construct flexible organic light emitting devices (FOLEDs), technology that could lay the groundwork for future generations of bendable television, computer and cellphone screens. "It opens up a whole new range of possibilities for the future," says Zheng-Hong Lu, a professor in U of T"s Department of Materials Science and Engineering. "Imagine a room with electronic wallpaper programmed to display a series of Van Gogh paintings, or a reusable electronic newspaper that could download and display the day"s news and be rolled up after use."

Today"s flat panel displays are made on heavy, inflexible glass that can break during transportation and installation. Lu, working with post-doctoral fellow Sijin Han and engineering science student Brian Fung, developed FOLEDs made on a variety of lightweight, flexible materials ranging from transparent plastic films to reflective metal foils that can bend or roll into any shape.

FOLED technology could be manufactured using a low-cost, high-efficiency mass production method, Lu says. The team, which is already commercializing some related technology, hopes a marketable device could be created within two to three years.

Their research was funded by the Canadian Foundation for Innovation, the Ontario Innovation Trust, the Premier"s Research Excellence Awards, Materials and Manufacturing Ontario, the Emerging Materials Network and the Ontario Research and Development Challenge Fund.

Flexible screens as thin as a piece of paper may be available for e-readers by early next year thanks to a project from Taiwan"s Industrial Technology Research Institute (ITRI) and licensee AU Optronics, one of the world"s largest LCD screen makers.

ITRI developed a manufacturing process for the thin displays and AU is in the process of converting an old factory to mass produce them, according to John Chen, general director of the Display Technology Center at ITRI.

"The beauty of this technology is you use today"s production technology," he said, adding that there"s no need to invest billions of dollars in a new factory, which would increase the price of the technology and any end-products it finally went into.

The partnership could lead to thin, flexible displays that could be added to mobile phones for a instant, pull-out screen to wearable screens on clothes or larger rolled up screens that serve the daily news at breakfast every day.

The current project is to make e-reader screens aimed at schools. The idea is that the flexible screens are more resistant to breaking, since they bend, and would make better e-readers for young children. The downside of the idea is that a new touchscreen function for the paper-thin screens is not quite ready, though it is also already being licensed by ITRI to another company that specializes in touchscreen technology.

The other point of the project is to move to brilliant color screens such as AMOLED (Active Matrix Organic Light Emitting Diode) in the future from the monochrome flexible screens that will be made for e-readers. Converting the AU factory to produce the thin, flexible screens is a project that will eventually lead to AMOLED and other kinds of paper-thin screens.

The flexible screens are so thin, around 30 microns, that they have to be bonded to a piece of glass during the production process so they don"t curl up, Chen said. Problems cropped up when they tried to lift the flexible screen off the glass at the end of the process because heat used in production caused the screens to bond to the glass, so they usually ripped. ITRI tried and failed 63 times to figure out a way to lift the finished screen from the piece of glass before a night out watching a cook led them to the result.

The cook used oil to lift thin Taiwanese crepe from a hot pan, fully intact. ITRI came up with a similar way to add a not-too-sticky material between the flexible display and the glass that enabled them to lift the flexible screen off the glass without a problem.

Currently, ITRI has developed paper-thin, flexible color AMOLED screens and the touchscreen film for displays 10-inches and smaller, according to Kung Chen-pang [CQ], project manager for the thin touchscreens. ITRI calls the touchscreen technology, Flexible Touch-sensing AMOLED film.

He did not say when the AMOLED screens might be available, but said ITRI has already licensed the technology to a private company in Taiwan. ITRI is a government sponsored research institute and its inventions are licensed globally, but first offer is usually given to Taiwanese companies.

"We don"t do an exclusive license," said Chen, noting that AU will face competition. He said companies from other countries will also be able to obtain licenses, and noted that one South Korean company had already gained a license, though he declined to say whether it was Samsung Electronics or LG Display.

Chen said that "volume will drive the price down," and that device makers will like the screens because they actually use less material since they"re thinner, are less expensive, preserve natural resources and more.

Flexible plastic OLCD displays will soon be a commercial reality, offering exceptional display integration potential for an almost limitless range of applications. Here are the key things you need to know about this exciting technology.

1) They’re flexible – in both senses of the word.It may seem like stating the obvious, but OLCD displays are lightweight, extremely thin and virtually unbreakable. This allows them to be wrapped around virtually any surface you encounter on a daily basis, with a bend radius down to just 10 mm.

2) They can be cut to almost any shape.Unlike glass, which is difficult to manufacture in anything but round or rectangular designs, OLCD displays can be quickly and easily cut to fit the shape of your product. You can even cut holes in the display without affecting performance, offering straightforward integration of anything from speakers and cameras to watch hands and toggle switches.

3) They have a low manufacturing temperature.The entire process takes place at below 100 °C, compared to 300-500 °C for silicon-based transistors. This dramatically reduces the cost of manufacturing flexible displays, by simplifying handling and allowing the use of lower cost plastics, as well as drastically lowering energy consumption during manufacturing.

4) They are scalable. The low cost and simple manufacturing process for OLCDs can be scaled to large sizes using standard equipment. This allows flexible plastic displays to be used for everything from smart watches and notebooks to ultra-thin, bezel-free monitors and TVs in the future.

5) They offer all the benefits of glass LCD displays. By sharing many of the components of traditional LCD displays (as well as the supply chain), OLCDs are a known quantity, with no trade-off in screen performance compared to their glass counterparts. They are robust enough to deal with vibrations and large temperature variations, and can be made bright enough for outdoor use without compromising lifespan, ideal for use in vehicles as well as consumer electronics.

This flexible display technology, developed by our world-class team, is ready to be brought to mass production. We can’t wait to see the innovative and unexpected uses OLCD displays are put to in the future. If you are looking for a flexible display solution, get in touch with us at info@flexenable.com.

Printed electronics is an all-encompassing term for the printing method used to create electronic devices by printing on a variety of substrates. As demand for wearable devices and thinner electronics expands, printed electronics are being used to form flexible displays, antennas, sensors, soft energy devices and more. In this chapter, the background of printed electronics is addressed and the contents of this book are described.

Modern printing technology involves a number of interdisciplinary areas, including engineering, information technology, physics, chemistry and materials science. To date, printing technology has not been universally accepted as a strict definition, but broadly it can be said that printing is a process of transferring information from the printing ink to the printing substrates through a graphic carrier such as a printing plate (master) in order to realize information (including graphics, images, patterns and text) transfer, which is a large-scale replication process (see Box 1.1).1 According to the intrinsic features of printing technology, it can be divided into two types, printing with a master and printing without a master. The former mainly includes offset printing, gravure printing technology, letterpress printing technology (including flexographic printing technology), and screen-printing technology, while conventional inkjet printing technology is the main representative for printing without a master. Printing technology has long been used in the manufacture of traditional industrial electronics, such as in the manufacture of cathode-ray tube (CRT) displays, in which the shadow mask is produced by printing and etching. In the manufacturing process of a traditional circuit board, the line pattern is obtained by printing and etching treatment.

Recently, printed electronics technology has attracted the widespread attention of researchers in both basic and applied research because this technique could be used to fabricate large-scale flexible electronic devices.

Large-area electronic devices mean large device sizes, which are far larger than the current focus of traditional semiconductor technology, as well as overall integrated devices or device arrays of tens of centimeters or even tens of meters.2 As shown in Figure 1.1, traditional electronic manufacturing technology includes photolithography, vacuum evaporation, electroless plating and etching methods, which are used to manufacture radio frequency identification (RFID) antennas. The total preparation process is relatively complicated and the required equipment cost is relatively high. This process often requires a number of chemical treatments and more energy consumption. Because the production line is too long, it is difficult to achieve the fast and high-volume preparation of flexible electronic devices. Therefore, there is an urgent need to develop new preparative techniques with high-speed, low-cost and environmentally-friendly features, which are beneficial to accelerate application in conductive patterns, transparent electrodes, RFID tags, thin film transistors, solar energy cells, sensors and other applications. Clearly, printed electronics technology becomes a strong candidate to meet these requirements. In addition, the development of printed electronics technology can also be used as an effective complement to the traditional preparation technology of electronic devices, and further realize the large-scale, high-speed preparation and large-scale application of functional micro-/nanoscale electronic devices.

The development of printed electronics technology will bring new opportunities for the transformation and upgrading of traditional print manufacturing enterprises. This is because the manufacturing of modern flexible electronic products requires the application of traditional printing manufacturing principles. As shown in Figure 1.2, the printed electronics technology possesses many advantages, such as high production speed, high automation and suitability for mass and large-scale production. The amount of printed electronics inks utilized could be controlled by the thickness of the printed layer, and the printing film is relatively thin, resulting in production costs being further reduced. Therefore, printed electronics technology enables the production and manufacture of thin, flexible, wearable, light weight, ultra-cheap and environmentally-friendly electronic products, which is one of the main directions of the development of modern electronic technology.

Printed electronics is not a new technology, and as early as 1950, researchers at Nippon Telegraph and Telephone had applied gravure technology into the manufacture of printed circuit boards (PCBs), and found that this technology can achieve mass production.3 In fact, a large number of printed electronics products have appeared in the market or in our daily lives. For example, in our laptop keyboard, the electronic circuits corresponding to the keys are often fabricated by screen-printing technology, as shown in Figure 1.3a. In addition, most RFID antennas (Figure 1.3b), smart tags (Figure 1.3c) and interactive printed products (Figure 1.3d) are often closely related to printed electronics technology.

As shown in Figure 1.4, unlike traditional silicon electronic manufacturing technology, printed electronics technology has the advantages of a simple manufacturing process, small loss of raw materials, less equipment investment, and can realize large area, lightweight, flexible and low-cost production. However, the downside of printed electronics technology is that in the current level of integration, information capacity, resolution, etc., still cannot reach the level of the silicon-based microelectronic manufacture process. Room temperature printed electronics processes can significantly reduce energy consumption, which makes thermally-sensitive and low-cost plastic film, paper and textiles realize the conductive function, and finally achieve large area, lightweight and flexible electronic product fabrication and applications.

Indeed, as a quasi-additive-manufacturing process, printed electronics technology can eliminate most of the environmental pollution problems, because it is the chemical etching processes in traditional electronics fabrication processes that generate the waste discharge. Therefore, printed electronics technology can be known as a green manufacturing technology. Furthermore, the printed electronics technique can solve the problem of environmental pollution caused by the increasingly serious electronic product waste by increasing the utilization of printable organic materials with good degradability and substrate. Although the performance and integration degree of printed electronic devices cannot yet reach the level of silicon-based microelectronics devices, these advantages enable printed electronics technology to have many various potential applications. Owing to its specific properties, printed electronics technology offers good complementarity and extension to silicon-based microelectronics, for both to meet the existing requirements.4 Printed electronics has the biggest advantage of electronic devices and circuitry because it is a low-cost technology.

Briefly, the mainly advantages of printed electronics technology includes three aspects as follows. First, printed electronics technology often uses much cheaper manufacturing equipment than the conventional microelectronics technology. Second, printed electronics technology reduces the complexity of the electronics manufacturing process and eliminates the requirement of photolithography or other burnishing processes, which is a significant advantage that reduces overall manufacturing steps, raw material costs and overall processing costs of electronic components. Third, printed electronics can use low-cost, high-volume, automated roll-to-roll (R2R) manufacturing processes. If all the functional printed electronics inks are mature, the utilization of printed electronics technology will greatly increase production efficiency and further reduce manufacturing costs.

Printed electronics technology has attracted widespread attention and because of this is set as an important technology for the manufacturing of large-area and flexible electronic devices by the patterned application of functional inks.5 Therefore, printed electronics technology utilizes the printing principle to realize the patterning of electronic tracks, electrodes, circuits and electronic devices. The electronic functions mainly come from the water-/oil-soluble inorganic or organic material inks, and generally these inks are the inorganic–organic composite materials. As mentioned, printed electronics technology has the advantages of thinness, flexibility, low-cost features, which can realize mass production and high-speed production. Therefore, printed electronics technology becomes the development direction for transforming and upgrading the traditional printing industry and modern microelectronics manufacturing industry.

Printed electronics involves a large number of basic disciplines, including the generic technology of materials, physics, chemistry, printing science and technology and electronic science and technology. Functional inks play a key and primary role in printed electronics technology. The development of environmentally-friendly, low-cost functional electronic inks is still an urgent issue in printed electronics. Subsequently, how to improve and elevate the printing accuracy and repeatability is another important issue in the printed electronics field, which would be beneficial to achieve the integrated manufacturing of complex micro-/nano-scale devices. Therefore, on one hand, the main task of printed electronics is to ensure that electronic inks can be transferred to the desired location effectively, and on the other hand to ensure that the quality of the printed film after post-treatment is good, and the final performance is close to the electrical properties of the bulk material of electronic components. Hence, the printing resolution, printing precision and ink transfer volume are the important parameters in the printed electronics quality control; that is, being as small as possible for printable size, as much as possible for the printing pattern accuracy, becomes very important. In addition, we also need the printing speed to be as fast as possible. The main and important elements involved in printed electronics are shown in Box 1.2.

Although printed electronics technology continues to move forward, there are still some problems that need to be solved before it becomes a mainstream electronic manufacture technology. The main limitations of printed electronics technology are listed as follows:

(i) The resistance of conductive inks is relatively large for fabricating electronic functional printed devices. Compared with traditional electronic devices, the total resistance of printed electronics products is generally not two or three times, but a hundred times, a thousand times or much more. If using the best conductive Ag ink, the resistance is still higher than about 10 times. Such a big difference causes the entire circuit to be like a resistor, and hence you must change the circuit design prerequisites to avoid this problem.

(iii) In essence, electronic circuits made by printing cannot be used as high-frequency circuits. High-frequency circuits are basically composed of passive components, active devices and passive networks. These components used in high-frequency circuits and the components used in low-frequency circuits have different frequency characteristics. Passive linear elements in high-frequency circuits mainly include resistors, capacitors and inductors. This limitation has been resolved recently because the conductive inks" performance is continuously improving.

In recent years, these problems or limitations of printed electronics technology are gradually being solved. For example, the use of thick-film printing circuits and maintaining increased precision of printing technologies both reduce the disadvantages of printed electronics technologies. Compared with the traditional manufacturing processes, printed electronics technology exhibits the advantages of a simple production process, small loss of raw materials, less equipment investment, low production costs, and becomes a green and popular manufacturing technology. However, it must be pointed out that printed electronics cannot replace silicon-based electronics but the technology is effectively complementary.

Printed electronics technology has been applied in many fields, as shown in Figure 1.5, including conduct line and electrodes, flexible displays and lighting, sensors and printed field-effect transistors (FETs), energy conversion and storage devices (solar cells, capacitors, etc.), and smart and interactive packaging.6 Currently, printed electronics involves a series of technical applications, from individual small-size electronic devices to large-area electronic device arrays or integrated electronic products. Innovations in printing technology make it possible to realize mass production of electronic devices at low cost on soft plastic, paper or textile substrates. This flexibility will enable printing and flexible electronics to be integrated into everyday objects and places that we previously dreamed of.

Currently, many printed electronics products have been applied into our daily lives. However, the basic and applied research of printed electronics technology is still ongoing toward reaching maturity and replacing a very large number of traditional manufacturing fields. According to the statistics of IDTechEx, printed electronics belongs to the emerging industries in the world. Most of them are still in the exploratory stage. At present, there are about 3000 printed electronics enterprises and institutions in the world, with 1050 in Europe, followed by 975 in North America and 825 in East Asia, which are the world"s three key zones of the printed electronics industry. Additionally, academic institutions and companies each account for 50% in the printed electronics field. Among the 3000 enterprises and institutions, there are about 860 organizations engaged in solar cells" related products, 810 organizations working on display-related and lighting-related products, 550 organizations for transistor-related products and 780 organizations for other products. Many well-known electrical, chemical and chemical industry companies have now entered and invested in the printed electronics field, such as Siemens, Motorola, Intel, Toshiba, Samsung, Sony, Phillips, Honeywell, GEHP, BASF, Bayer, DuPont and Merck, etc. The European Union has invested more than a billion euros in financing for the development of printed electronics and related products as early as the fifth and sixth frameworks (FP5 and FP6) and the latest FP7. Therefore, the mainstream products in the printed electronics market include solar photovoltaics, displays, lighting and other wearable electronic devices. Other products are mainly printed functional circuits, batteries, transistors, sensors and smart integration systems. The research progress is very rapid and the scale of technology development is huge.

Conventional incandescent lamps have similar full-spectrum properties to daylight and have a color rendering index of 100, which could provide the most realistic lighting experience. However, the biggest disadvantage of the incandescent lamp is the low luminous efficiency. It is clearly wasted energy in the context that lighting energy consumption accounts for almost 18% of the total global energy consumption. In addition, the life of an incandescent lamp is very short, so frequent replacement also increases the overall resource consumption. In contrast, a fluorescent lamp greatly improves light efficiency and saves more energy. However, the biggest disadvantage of the fluorescent lamp is that it contains the poisonous material mercury. If there is no matching recovery system in the future, the environment will be greatly polluted by mercury, because if mercury enters into surface water then it will easily transform into highly toxic methylmercury. Once it is absorbed by fish and enters the biological chain, this will bring huge ecological damage (mercury pollution is hard to eliminate) and endanger human life and health.

In recent years, with the continuous development and innovation of lighting technology, light-emitting diodes (LEDs) have gradually become the predominant light source. The LED exhibits many advantages including high efficiency, long life, is mercury-free and UV radiation-free as well as having other characteristics, which makes it a new generation of promising lighting source. However, the LED possesses an intrinsic pointolite characteristic, resulting in many applications requiring a large number of LED combinations, increasing the complexity of the lighting system, while reducing the overall output light efficiency. It is noteworthy that organic light-emitting diode (OLED) technology has also been utilized in the field of lighting. The OLED not only possesses similar advantages to the LED, but also has some unique advantages, including its intrinsic surface light source characteristics, uniform overall lighting, soft lighting reducing the glare effect, and the preparation process doesn"t need light guiding. These features greatly simplified the system complexity, and improved the lighting efficiency of the entire lighting system, and finally reduced the overall system energy consumption. Compared with the LED, the spectra of the OLED are very close to natural sunlight, and hence the observation of objects is quite natural. Moreover, OLEDs have more significant power-saving features, which is very helpful for their development in the field of lighting. Therefore, OLEDs and LEDs show a complementary relationship and both techniques will be significantly developed in the future.

At present, the lighting industry is going through a drastic transformation. Traditional incandescent bulbs have gradually disappeared in many countries in the world. They have been replaced by power-saving light bulbs and LED lights. As such, printed electronics technology has been widely used in the modern lighting industry for saving costs and creating novel products. Printed electronics technology becomes particularly important in the field of modern lighting because it can drive revolutionary lighting products and reduce the cost of those products, with only a few obstacles to overcome in the current. A well-known lighting company, Osram, demonstrated that printed electronics technology has been utilized in the manufacture of OLEDs. As shown in Figure 1.6a, the structure of an OLED is very simple and suitable for printing manufacturing. The luminous efficiency of the currently available OLED is about 80 lm W−1, much lower than the LED (luminous efficiency of more than 100 lm W−1) and the luminous efficiency of energy-saving light bulbs. In 2013, the Panasonic Corporation announced that it had developed a white OLED with the highest luminous efficiency of 114 lm W−1 (light-emitting area of 1 cm2) in the world. Moreover, the luminous efficiency of a larger device with an emitting area of 25 cm2 has reached 110 lm W−1.7 It is encouraging to learn that recent progress reveals that the luminous efficiency of the currently available OLEDs is higher than 130 lm W−1 in 2017. As shown in Figure 1.6b, the Rohinni company invented LightPaper, which is fabricated by mixing ink and micro-LEDs together and printing them on a conductive layer. This is then sandwiched between two other layers and packaged. The size of these micro diodes is close to the size of red blood cells and they are dispersed randomly in the ink. When current flows through the diode, it lights up. It is a way to print lighting and apply it to nearly any surface, in any shape and for any situation. In fact, the current research on printed electronics technology has covered all aspects of LED and OLED manufacturing, and it is expected to achieve significant results in the next decade.

Obviously, printed electronics technology is considered to be an effective way to solve the cost and area issues of OLEDs, which can combine functional inks and advanced printing equipment to make large-scale OLED lighting devices that can improve the material utilization and production efficiency, reduce manufacturing costs and increase productivity, and hence printed OLEDs will become a promising and mainstream product in the future. Moreover, if the printing accuracy continues to improve, LED manufacturing and packaging will also be used in printing technology in the future.

Printing technology has long been used in the production of traditional solar cells. For instance, precision printing the fine circuitry on both the front and back of a wafer is one of the most critical processes in the production of conventional crystalline silicon solar cells, which is used to transfer the photo-generated electrons out of a cell. Typically, several screen-printing steps are utilized in the entire crystalline silicon solar cells" production process, and rapid sintering processes are subsequently used to achieve the electrode and the silicon substrate forming a good ohmic contact. The cost of solar power has plummeted in the past few decades, from $40 per watt in 1977 to $0.63 per watt in 2014. The development of printed electronics technology will further promote the emergence of low-cost solar cells; the biggest merit will be used to create flexible solar cells and promote the further development of related industries. As shown in Figure 1.7, the VTT Technology Research Centre in Finland recently released an attractive, soft, fully recyclable organic solar panel, and a variety of moldings and designs could be printed on the panel. The current solar panels have been able to achieve mass production. By pattern designing, the panels can be assembled in any form of wallpaper to capture any suitable solar energy. The thickness of the as-developed solar panels is only 0.2 mm. The repeat length (LR) is defined as the circumference of the printing cylinder/screen and the LR of the roll-to-roll machines is about 410 mm; therefore, 50 repeat lengths correspond to a web length of 20 m. Through the roll-to-roll printing manufacturing process, the polymer light-harvesting layer, electrode lines and the surface pattern can be cast at a speed of 100 m per minute into the plastic fil