flexible lcd displays free sample

FlexEnable’s glass-free organic LCD (OLCD) delivers high-brightness, long lifetime flexible displays that are low cost and scalable to large areas, while also being thin, lightweight and shatterproof.

OLCD is a plastic display technology with full colour and video-rate capability. It enables product companies to create striking designs and realise novel use cases by merging the display into the product design rather than accommodating it by the design.

Unlike flexible OLED displays, which are predominantly adopted in flagship smartphones and smartwatches, OLCD opens up the use of flexible displays to a wider range of mass-market applications. It has several attributes that make it better suited than flexible OLED to applications across large-area consumer electronics, smart home appliances, automotive, notebooks and tablets, and digital signage.

OLCD can be conformed and wrapped around surfaces and cut into non-rectangular shapes during the production process. Holes can be also added to fit around the functional design of the system – for example around knobs and switches.

As with glass-based LCD, the lifetime of OLCD is independent of the display brightness, because it is achieved through transmission of a separate light source (the backlight), rather than emission of its own light. For example OLCD can be made ultra-bright for viewing in daylight conditions without affecting the display lifetime – an important requirement for vehicle surface-integrated displays.

OLCD is the lowest cost flexible display technology – it is three to four times lower cost that flexible OLED today. This is because it makes use of existing display factories and supply chain and deploys a low temperature process that results in low manufacturing costs and high yield.

Unlike other flexible display approaches, OLCD is naturally scalable to large sizes. It can be made as small or as large as the manufacturing equipment used for flat panel displays allows.

The flexibility of OLCD allows an ultra-narrow bezel to be implemented by folding down the borders behind the display. This brings huge value in applications like notebooks and tablets where borderless means bigger displays for the same sized device. The bezel size allowed by OLCD is independent of the display size or resolution. In addition, OLCD can make a notebook up to 100g lighter and 0.5mm thinner.

OLCD is the key to the fabrication of ultra-high contrast dual cell displays with true pixel level dimming, offering OLED-like performance at a fraction of the cost. The extremely thin OLCD substrate brings advantages in cost, viewing angle and module thickness compared to glass displays. At the same time OLCD retains the flexibility required for applications such as surface-integrated automotive displays.

Due to its unique properties, OLCD has the potential to transform how and where displays are used in products. The videos below give a glimpse into this innovative technology.

OLCD brings the benefits of being thin, light, shatterproof and conformable, while offering the same quality and performance as traditional glass LCDs. The mechanical advantages of plastic OLCD over glass LCD are further enhanced by the technology’s excellent optical performance, much of which originates from the extreme thinness of plastic TAC substrates compared to glass.

How many times did you start to plan a project and thought to yourself “if only I had a display that can fit within this design”? How many times did you alter the whole design because there were no displays available on the market that went with your idea?

Different displays have different characteristics, just tell Panox Display your application, and operating environment, Panox Display will suggest a suitable display for you.

Being completely made of plastic, Lectum® displays are much more rugged than standard glass-based EPDs. They are also thinner and lighter per square inch than conventional EPDs and are inherently low-power, which is vital in today’s increasingly mobile world.

LG Disply has developed a 12-inch stretchable display that can be extended in size to 14 inches, the company announced. The displays could one day be used in materials with irregular surfaces like clothes and wearables to display messages on the uniforms of first responders, for example.

Stretchable displays, or free-form displays as LG Display calls them, can be pulled, bent and twisted. They go a step farther than the flexible displays used in Samsung"s Galaxy Fold and other smartphones, which can be folded and bent but not stretched.

We"ve seen stretchable displays in the past from Samsung and others, but the best you could do with those was put a small dent in them. This one appears to go much farther, showing the potential for displays with real potential for wearables. LG Display has been working on the technology since 2020 in collaboration and the research is expected to conclude in 2024.

Finally! A flexible OLED display module. This is a super-bright 160x32 pixel, flexible OLED display. This next-generation flexible OLED module is super-cool! It"s highly reflective so taking a photo is rather tricky, but we"re confident once you get one of these displays in your hand you"ll be impressed! We"re hopeful this is just the start of more flexible OLED technology coming to market.

Flexible displays open up new dimension of design opportunities that aren’t possible with rigid glass-based displays. Nowadays, users have come to expect touch capability from almost any display-enabled device, but, many devices still need certain buttons or knobs – for example in cars. This becomes a limitation when using rigid glass displays - designers need to allow for additional space for knobs or buttons outside the display area. This can waste space, compromise aesthetics and result in a bulky non-optimised design.

Recently, some display makers have introduced glass displays with through-holes for the camera in smartphone screens. For example, Tianma has recently announced a 6.4” LCD with a through-hole that will be used in Huawei’s nova 4 device. It becomes more challenging and more expensive if the holes or the displays are larger, or if there are multiple holes required, when the displays are made from glass

In order to make displays flexible, the transistor backplane technology used needs to be flexible. This is currently made possible using conventional silicon technology or metal oxides on bespoke polyimide substrates. Flexible displays need to be mounted onto glass in order to keep them flat during fabrication. At the end of the process the flexible displays need to be demounted from the glass carrier by using a laser de-bonding process. Holes can be cut through the displays before or after the de-bonding process. If the demounting process is aggressive, like in the case of laser de-bonding for the polyimide-based displays, it can generate unwanted stresses which will cause the edges of the holes to be concentrated stress relief areas and hence impact yield and cost.

FlexEnable has developed a different approach for flexible displays. By using low temperature processing of organic thin-film transistors (OTFTs) on low cost plastics like triacetyl cellulose (TAC), no laser de-bonding processes are required. Instead a mild heat or UV treatment is used to separate the flexible displays from the glass. Holes through the displays are laser profiled while the displays are still mounted onto the glass. Unlike polyimide-based displays, OTFT displays have a simple high yielding demounting process.

There will continue to be applications that require the use of knobs and buttons even if they feature touch-enabled displays. Imagine a car’s central console which is a touch–enabled display, but the volume dials and gear stick protrude through the display. As kitchen appliances become smarter with the use of displays, they may still require physical dials to control certain functions. Wearables like smart watches can combine the digital look of a smart watch with the mechanical dials of a conventional arm watch.

As the landscape for flexible displays evolves with new use cases, the ability to cut holes through the displays unlocks even more design freedom and enables bolder product designs to meet growing consumer expectations.

Among the various improvements that smartphones and tablets have received over the last decade, flexible displays are undoubtedly one of the most interesting propositions and one with a huge potential to change the market. The technology is still relatively new, despite several companies exploring the tech for more than a decade.

After seeing several new devices successfully integrate flexible displays with varying levels of success, it"s clear that this tech is here to stay. The only question right now is how long it will take for flexible displays to become commonplace. Let"s take a look at how modern flexible displays work and future considerations for this corner of the market.

Smartphone displays are traditionally rigid due to the glass layer used in their production. However, modern OLED-based designs have successfully removed the need for that, instead implementing the screen in a very thin layer, to the point where it becomes flexible. The screen is then covered with a thin plastic layer, which is unfortunately susceptible to scratches.

In some cases, flexible displays are just an illusion. Some devices feature two or more displays lined up next to each other, with special emphasis placed on removing the border between them. These devices are usually more versatile in terms of the kinds of upper layers they support, in some cases including a full glass cover.

Flexible displays have been around for a decade now. Initial designs were rather underwhelming—but some of them ended up being repurposed into other devices. For example, the Galaxy Note Edge"s curved screen actually started as a prototype for a flexible display device.

The Galaxy Z Flip 3 is a notable example of a device that incorporates a flexible display, and some claimed that it should set some new trends on the market. Unfortunately, other manufacturers haven"t tried to follow the trend, so it remains to be seen whether the idea has any true potential. The device sold well enough, which is a good sign.

And in some cases, flexible displays were used to achieve a different effect. The iPhone X, which started the trend of screens with curved corners, actually used a flexible display to accomplish that without sacrificing any real estate around the bezels.

Flexible displays remain relatively expensive compared to their regular counterparts and often sacrifice visual quality. This is especially noticeable when the screen is folded at a particular angle. At the same time, flexible screens tend to have a more limited lifetime compared to traditional ones.

For most user"s needs, current designs should be able to last a very long time. But this is still a point that needs to be addressed by most manufacturers, especially in the context of the higher prices attached to flexible display devices.

It"s also important to note that flexible displays have huge potential outside of the smartphone market. Other devices can utilize them to improve their usability. Furthermore, with wearable gadgets increasing in popularity, new gadgets coming out in the future are likely going to take advantage of this technology.

Smartwatches are a good candidate for flexible display technology. Their designers already go to great lengths to make their displays as compact as possible, and flexible displays offer some direct advantages in this regard. They tend to be thinner than traditional displays, which makes them a good fit for devices of this kind.

Then there are medical devices and other specialized use cases. Even if flexible displays don"t immediately take off, they will find a place in other areas. It will be interesting to see what kinds of changes they facilitate in other markets.

Gaming is also shaping up to be a field where these devices could have a viable place. Between virtual reality and the new features being introduced in modern consoles and their controllers, we might see some approaches that integrate flexible displays.

With all that said, the main question remains—will this eventually become a common trend on the market as a whole? As we mentioned above, there are specialized cases where bendable or flexible displays have potential.

But at the same time, it"s questionable how fast this tech will be adopted in general, depending on price, application, and other availability factors. New developments in the field have made the production process more affordable, but it will probably take a while until foldable displays establish a permanent presence on the market and become commonplace.

Smart packaging is arguably the low-cost display application with the greatest scope for growth. Displays can be integrated into both shelf-level and item-level packaging, with the former likely to emerge first since the lower volumes enable higher unit costs. At present, electroluminescent displays are sometimes incorporated into limited edition production runs for marketing processes, but these are not regarded as an effective long-term solution due to their high power requirements.

Another application for low-cost displays is small consumer goods. This has long been the case for some premium items such as electric shavers, with small displays that show the remaining charge, for example. However, as displays get cheaper and electronic functionality/wireless capability is integrated into more devices, this could be expanded to an ever-growing range of devices and appliances. Indeed, it might not be long before bank and travel cards contain a low-cost display to show your balance and/or recent transactions.

Wearable technology is another promising application for low-cost displays. While OLED displays are widely used smart watches, they are generally too expensive at present to incorporate into clothing and skin patches for medical/fitness/therapeutic applications. The key attributes for displays in clothing and skin patches are durability, flexibility, and low power consumption. This example demonstrates that for many emerging display applications, the traditional key performance indicators of resolution, color gamut and refresh rate are no longer especially important.

Smart packaging is arguably the low-cost display application with the greatest scope for growth. Displays can be integrated into both shelf-level and item-level packaging, with the former likely to emerge first since the lower volumes enable higher unit costs. At present, electroluminescent displays are sometimes incorporated into limited edition production runs for marketing processes, but these are not regarded as an effective long-term solution due to their high power requirements.

Another application for low-cost displays is small consumer goods. This has long been the case for some premium items such as electric shavers, with small displays that show the remaining charge, for example. However, as displays get cheaper and electronic functionality/wireless capability is integrated into more devices, this could be expanded to an ever-growing range of devices and appliances. Indeed, it might not be long before bank and travel cards contain a low-cost display to show your balance and/or recent transactions.

Wearable technology is another promising application for low-cost displays. While OLED displays are widely used smart watches, they are generally too expensive at present to incorporate into clothing and skin patches for medical/fitness/therapeutic applications. The key attributes for displays in clothing and skin patches are durability, flexibility, and low power consumption. This example demonstrates that for many emerging display applications, the traditional key performance indicators of resolution, color gamut and refresh rate are no longer especially important.

For decades displays have been simply flat pieces of glass or plastic that dictated the design of technology. But recently, engineers and manufacturers have been coming up with curved screens, more and more of which can be found on computer monitors, televisions and phones.Samsung Galaxy S7 Edge and LG G Flex are among the devices featuring bendable display.

With bendable display, manufacturers are looking to advance technology. In fact, flexible displays have the potential to become one of the biggest technological breakthroughs in the decade, encouraging designers to create devices we have never seen before.

Although curved screens are impressive, these are not the same as the ones that are bent. Traditionally, liquid-crystal displays (LCDs) are sandwiches with materials that include backlight, polariser, thin-film transistor, liquid crystals and filter glass. LCDs are usually flat, but several companies like Samsung have managed to produce curved LCDs.

The recently released organic LED ecosystem (OLED) has gained popularity, thanks to its simplified design, better image quality and flexibility. OLED displays do not require backlighting, so these can be thinned and moulded into specific shapes such as the curved display on Samsung Galaxy S7. Flexibility, thinness and excellent image quality make OLED a better choice for curved screens, and it is clear that the OLED will overthrow LCD TVs in the future. However, OLEDs are currently too expensive to produce for large screens such as televisions and computer monitors, but their prices will eventually fall.

Although LCDs contain more layers than OLEDs, these screens may still be bent. Apple Japan Display is developing a 14cm (5.5-inch), full HD LCD. The display will use plastic for the substrate, which has traditionally been made of non-removable glass. This will enable it to flex and bend.

The biggest advantage of flexible displays is durability. Because the screen can be bent and manipulated, it can also absorb impact better than solid glass structures we currently have. So broken screens can be a thing of the past. However, it will take some time before we reach that point. It is assumed today that bendable screens will use plastic instead of glass, but the plastic itself can still crack under extreme stress.

Manufacturers like Corning are currently working on a flexible glass called Willow, which is planned to be put into everything from telephones to televisions to carry devices. Willow is as thin as a piece of paper and can be bent too. But it will still break if it gets too much rounded up.

The three largest mobile manufacturers are reportedly experimenting with flexible displays. According to Samsung, the most important feature of Galaxy X is that its display can be folded outside, allowing users to convert their phones into 12.7cm (7-inch) tablets. LG is also said to have come out with a smartphone that folds outside to form a tablet. Patent drawings represent a conceptual LG phone that has a foldable display which can be used even after bending. Apple is considering the use of bendable displays on the iPhone in 2018.

Other technologies could also benefit from flexible displays. For example, flexible displays could be used as clothing that changes colour or pattern instantly as per the environment, making these particularly useful for soldiers.

Phones can also take a new format, similar to the Lenovo Cplus prototype, which starts as a thin handset but folds into a wristband. Samsung experimented with the introduction of curved displays on its original Galaxy Gear S smartphone, but moved to a more traditional flat, rounded Galaxy Gear S3. With curved displays, intelligent observers can theoretically have massive screens that surround their wrist to display even more information at once.

Cars could also use curved screens as more and more dashboards are going digital. For example, Mercedes E-Class displays infotainment indicators and infotainment data on a 31cm (12.3-inch) HD display that extends on the dashboard. Tesla and X models have a huge 43cm (17-inch) central display, but you can use a curved screen to make the outline look natural on the car’s dashboard.

The concept of bent displays is not new, because gadget manufacturers appear to be displaying them on large shows like CES (Consumers Electronics Show in Las Vegas, USA) and MWC (Mobile World Congress in Barcelona, Spain) annually, but no one has brought a flexible display to the market yet. Why?

HP and the Flexible Display Center (FDC) at Arizona State University (ASU) today announced the first prototype of affordable, flexible electronic displays.

Flexible displays are paper-like computer displays made almost entirely of plastic. This technology enables displays to become easily portable and consumes less power than today’s computer displays. Popular applications for the technology could include electronic paper and signage.

The production feat is a milestone in the industry’s efforts to create a mass market for high-resolution flexible displays. Plus, from an environmental standpoint, the displays leapfrog conventional display processes by using up to 90 percent less materials by volume.

Mass production of such displays can enable production of notebook computers, smart phones and other electronic devices at much lower costs since the display is one of the more costly components.

SAIL technology enables the fabrication of thin film transistor arrays on a flexible plastic material in a low-cost, roll-to-roll manufacturing process. This allows for more cost-effective continuous production, rather than batch sheet-to-sheet production.

“The display HP has created with the FDC proves the technology and demonstrates the remarkable innovation we’re bringing to the rapidly growing display market,” said Carl Taussig, director, Information Surfaces, HP Labs. “In addition to providing a lower-cost process, SAIL technology represents a more sustainable, environmentally sensitive approach to producing electronic displays.”

The first practical demonstration of the flexible displays was achieved through collaborative efforts between the FDC and HP as well as other FDC partners including DuPont Teijin Films and E Ink. To create this display, the FDC produces stacks of semiconductor materials and metals on flexible Teonex� Polyethylene Naphthalate (PEN) substrates from DuPont Teijin Films.

HP then patterns the substrates using the SAIL process and subsequently integrates E Ink’s Vizplex™ imaging film to produce an actively addressed flexible display on plastic. E Ink’s Vizplex bi-stable electrophoretic imaging film enables images to persist without applied voltage, thereby greatly reducing power consumption for viewing text.

“Producing a photolithography-free, flexible active-matrix display is an excellent example of the Flexible Display Center’s world-class development and manufacturing infrastructure,” said Shawn O’Rourke, director, Engineering, Flexible Display Center at Arizona State University. “It demonstrates how multiple industry partners can collaborate on innovative solutions, including roll-to-roll compatible technology that addresses the rapidly growing market for flexible electronics.”

“Flexible electronic displays are playing an increasingly important role in the global high-tech industry, serving as the crucial enabling technology for a new generation of portable devices, including e-readers and similar products designed to combine mobility with compelling user interfaces,” said Vinita Jakhanwal, principal analyst, Small and Medium Displays, iSuppli. “We expect the flexible display market to grow from $80 million in 2007 to $2.8 billion by 2013. The Flexible Display Center at Arizona State University is a key participant in helping to develop the technology and manufacturing ecosystem to support this market.”

The FDC is a government–industry–academia partnership that’s advancing full-color flexible display technology and fostering development of a manufacturing ecosystem to support the rapidly growing market for flexible electronic displays. FDC partners include many of the world’s leading providers of advanced display technology, materials and process equipment. The FDC is unique among the U.S. Army’s University centers, having been formed through a 10-year cooperative agreement with Arizona State University in 2004. This adaptable agreement has enabled the FDC to create and implement a proven collaborative partnership model with more than 20 engaged industry members, and to successfully deploy world-class wafer-scale R&D and GEN-II display-scale pilot production lines for rapid flexible display technology development and manufacturing supply chain commercialization. More information about FDC is available at

Backplanes are the most essential component of electronics because they can connect in parallel with each other and control the electrical signals of devices. As opposed to the passive-matrix form, the active-matrix backplane allows selective access to each component with a rapid response while maintaining a high-circuit density by sharing electrode lines. Despite many advantages of active-matrix backplanes, the realization of deformable active-matrix backplanes with reliable operation is very challenging. This is because three electrodes (gate, source, drain) of each component are connected to different word and bit lines and grounds, and the failure of only one single component can lead to the failure of the whole backplane. Therefore, it is important to minimize stress during deformations of thin-film transistor (TFT)-based electronics. The deformability of backplanes is commonly obtained by modifying device materials and structures to accommodate most of the strains induced by bending, folding, and even stretching. These modifications can be classified into two approaches: one uses intrinsically flexible materials (e.g., ultrathin or elastomeric materials) and the other uses an engineered substrate.

The most basic method of obtaining flexibility or bendability is the adoption of ultrathin materials as the TFT backplane components.2a, b. In addition, no fracture was found on the oxide semiconductor TFT regions due to the thin thickness of the backplane (~2 µm) and the improved flexibility of the TFT regions. Javey and coworkers have demonstrated a flexible display that is composed of a flexible carbon nanotube (CNT)-based backplane and flexible organic light-emitting diode (OLED) pixels as depicted in Fig. 2c, d (ref. 3). The flexible display was fabricated on a 24-µm-thick PI film, and the total thickness of the devices (excluding the substrate) was <2 µm. Therefore, the flexible backplane showed stable electrical characteristics even during the bending states (where the bending radius was 4.2 mm), and the OLED pixels also performed with negligible degradation from the deformations (where the bending radius was 4.7 mm). Consequently, this fabricated display also demonstrated flexibility because of the deformability of the devices.

Flexible backplane for display fabricated by a thin-film process. a Photo (left) of the TFT array sample made by graphene–AuNT hybrid electrodes on a transparent polyimide substrate. Scale bar: 1 cm. A schematic diagram (right) of the TFT layout. b Photos of the TFT arrays transferred onto: a leaf, eyeglasses, and the skin of human hand. All scale bars: 1 cm. a–b Reproduced with permission from ref. 8. Copyright 2014, American Chemical Society. c Photo (left), optical micrograph (middle), and scanning electron micrographs (right) of flexible backplane. d Photos of operating flexible display combined with backplane and OLED pixels. c–d Reproduced with permission from ref. 3. Copyright 2013, Nature Publishing Group

Many studies have demonstrated flexible electronics with various methodologies. However, in the case of the aforementioned methods, mechanical stresses continue to be induced on the brittle electronic materials, even though the stresses are relieved. Therefore, the mechanical stresses generate fatigue on the electronics during repetitive or constant deformations, and the accumulated fatigue causes severe problems that deteriorate the performance and reliability of flexible TFT backplanes. Consequently, reducing fatigue becomes a key challenge to realizing highly flexible and stable backplanes or electronics. The typical method of reducing mechanical fatigue on the TFT backplane is the adoption of device islands-interconnect designs. These designs are based on engineered substrates that are composed of materials with different values of elastic modulus.3a.1 summarizes the recent advances in stretchable interconnect technology.3b). The stretchable conductors showed high stretchability at over 200% strain as plotted in Fig. 3c. Based on these systems, the stretchable backplane also demonstrated superb stretchability up to the strain of 110% (Fig. 3d). In addition, Kim et al. have also demonstrated a reversibly foldable TFT backplane based on the oxide semiconductor (indium oxide (In2O3)), which shows high performance and is used in the conventional backplane.3e). The designed stretchable conductors exhibited stretchability up to the strain of 100% and also exhibited stability against cyclic tests (10,000 times with the 80% strain), as shown in Fig. 3f. Because of these superior interconnects and engineered substrates, the oxide semiconductor TFT backplane also showed high stability during the folding states without any degradation (Fig. 3g). In addition, Park and his team have also studied stretchable TFT backplanes based on these two systems Fig. 3h. Their TFT backplanes also provided reproducible performances up to the strain of 25%, as shown in Fig. 3i, and showed high stability against fatigue (5000 times with the 20% strain), as shown in Fig. 3j. The reliability of the stretchable TFT backplane is affected by the strain isolation effect of engineered substrates and the high stability of stretchable interconnects (Au film on AgNWs-embedded elastomer).

Device islands-interconnect design for highly flexible TFT backplane. a Simulation of strain manipulation at the top surface of the engineered substrate. Reproduced with permission from ref. 9. Copyright 2013, American Institute of Physics. b Schematic illustrations of OTFT backplane on engineered substrate. c Conductivity dependence on tensile strain in printed elastic conductors with and without surfactant. d Transfer characteristics of OTFT according to the tensile strain. b–d Reproduced with permission from ref. 12. Copyright 2015, Nature Publishing Group. e Schematic images (top) and scanning electron micrographs (bottom) of stretchable conductor (Au film on AgNWs-embedded elastomer) before and after stretching. Scale bars: 5 μm. f Resistance dependence on tensile strain (left) and cyclic numbers (right) of the stretchable conductor (Au film on AgNWs-embedded elastomer). g Images (top) and output characteristics (bottom) of foldable TFT backplane on engineered substrate before and after folding. Scale bars: 5 mm (black) and 100 μm (red). e–g Reproduced with permission from ref. 13. Copyright 2016, Royal Society of Chemistry. h Illustration and photograph (inset) of stretchable TFT backplane on engineered substrate. i Electrical properties of device in h according to the mechanical strain (up to a strain of 25%). j Electrical properties of device in h according to the number of cycles

The research activities for developing TSP technologies at UNIST have been devoted mainly to exploring new materials, device structures, and device fabrication processes for multi-functional flexible and stretchable TSPs. One noticeable achievement is the development of the highly flexible capacitive TSP with AgNW diamond-pattern electrodes and transparent bridge structures formed on a polycarbonate film.4 shows the structure and touch-sensing capability of the fabricated TSP. As shown in the Fig. 4, the bridge structure is composed of an epoxy polymer (SU-8)-based bridge insulator and an Al-doped zinc oxide (AZO) bridge electrode. In order to secure the stable and robust connection between the AZO bridge electrode and the AgNW diamond-pattern electrodes over the bridge insulator, the side-wall slope of the bridge insulator is made as low as possible with our unique photolithography process, in which the exposure time is extended beyond the optimized value for forming vertical side-walls. With the extended exposure time, the lower part of the SU-8 layer immediately adjacent to the direct exposure region can be sufficiently exposed to the stray ultraviolet (UV) light scattered from the substrate, leading to the formation of a bridge insulator with a low side-wall slope. The fabricated TSP sample was found to be highly flexible and transparent and also showed good touch-sensing performance. The measured capacitance changes by ~22.7% with the finger touch.

Based on their superb operational performances and functionalities, the flexible and stretchable TSP devices developed at UNIST, including the two introduced above, are expected to significantly enrich the information communicated between humans and machines. Thus, it is quite probable that these devices will be used extensively in various future information technology applications.

Flexible light sources are important parts in flexible display applications because they determine long-term stability and commercial value of practical flexible displays under continuous mechanical stress. Thus, flexible light sources should have sufficient light-emission efficiency and mechanical stability. Generally, OLEDs have been mostly spotlighted candidates for flexible light sources because OLEDs consisted of organic materials and they have outstanding mechanical flexibility compared with inorganic LEDs.

Following constituent materials of flexible OLEDs, there are four major research issues (substrates, electrodes, light-emissive materials, and encapsulation) to be perfectly developed for practical future applications; flexible substrates, electrodes, light-emissive materials, and encapsulation. Here, we briefly introduce technical research issues with four sections and suggest future research directions of flexible OLEDs.

Almost all of the macroscopic flexibility of flexible OLEDs comes from substrates. The important properties of flexible substrates are mechanical flexibility, thermal stability, optical transparency, and gas barrier properties.

Highly conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have been investigated for flexible electrodes with highly smooth surface, optical transparency, easy processes, and enhanced electrical conductivity up to 4380 S/cm by doping with polar solvents or concentrated sulfuric acid.6. In addition, hybrid flexible electrodes composed of PEDOT:PSS and AgNWs were said to be mechanically durable and robust OLED characteristics were said to be obtained.

a Schematic illustration of thermal annealing and LPEB irradiation of AgNWs. b Schematic illustration of fabrication process for AgNW/PEDOT:PSS composite electrode and the PLED structure, and photograph of light-emitting flexible PLEDs with AgNW/PEDOT:PSS electrode

Most components of flexible OLEDs are organic materials that can easily react with oxygen and moisture because plastic substrates and other components have low gas barriers. The water vapor transmission rate (WVTR) is strongly related to the long-term stability and feasibility of practical flexible OLEDs. OLEDs generally require a WVTR of approximately 10−6 g/m2∙per day, which is a very low value compared to inorganic LEDs.−3 g/m2∙day, as shown in Fig. 8.

For next-generation displays, flexible and light-weight OLEDs are an appropriate candidate because of their excellent light emission, and mechanical flexibility. Currently available components of flexible OLEDs including substrates, electrodes, emissive materials and encapsulation layers, are still insufficient to achieve practical flexible OLEDs with stable performance under mechanical deformation. Consequently, achieving reliable components of flexible OLEDs such as (1) flexible substrates and encapsulation layers with good barrier properties, (2) transparent electrodes that are mechanically robust under deformation and have low sheet resistance, and (3) flexible materials that emit light efficiently, remains to be solved for commercial applications.

Recently, flexible display devices have attracted widespread attention as an alternative to rigid devices because of their portability and comfort for long time wearing. For the relevant applications, when the devices undergo mechanical deformations such as bending and stretching, the thicknesses of the constituent materials usually decreases and all layers suffer a tensile stress at the outside of each layer.

Flexible display devices contain many laminated structures composed of sub-micrometer-scale thin films. At UNIST, we evaluated the mechanical properties of one of these components using modified hole-nanoindentation. PDY-132 (Merck, Germany, commercially sold as “Super Yellow”) is a ‘‘high-performance polymer’’ that emits yellow light. In our evaluation, PDY-132 was spin-coated on a clean glass substrate. The sacrificial layer was selectively dissolved to fabricate free-standing films with the same dimensions as the actual devices. We fabricated hole-patterned Si wafers using the deep reactive ion etching method. The patterned hole size was proportional to each film thickness, so that the diameter of a hole was less than 1% of the film thickness.11. The elastic modulus of the hole-indentation was found to be 4.89 GPa, and its fracture strength was 1.19 GPa.

Uchic et al.12. Tensile testing is the most fundamental method of evaluating a material’s inherent mechanical properties, such as yield strength, strain-hardening exponent, ultimate tensile strength, etc. As mentioned above, in-situ testing enables precise observations of sample deformations in real time, with simultaneous imaging during testing. Various indenters are also expected to enable stretching and bending tests of constituent materials in flexible display devices.

Flexible display devices contain many organic materials, such as polymer films, active materials, and electrodes. However, mechanical tests of organic materials in high vacuum conditions in SEM and transmission electron microscopy are limiting in that organic materials are (in real environments) highly affected by surrounding environmental conditions such as humidity and temperature; it is important to measure mechanical properties in actual operating environments. A nano-UTM can be used to control environmental conditions using a controlled humidity chamber and heating block because the machine is based on an optical microscope, as shown in Fig. 13. Images of gauge sections during tensile tests are observed by a charge-coupled device camera in real time, and strain is analyzed from the images based on digital image correlation. Constituent materials in flexible display devices are macroscopically visible and their thicknesses are generally in the nanometer-scale range. PEDOT:PSS is widely used for organic transparent conducting electrodes, and PEDOT:PSS thin films are fabricated by natural drying after drop casting on a substrate. A tensile sample was fabricated by a mechanical press, and the gauge length and gauge width were 4 and 1 mm, respectively, as in the standard ASTM E8 test. We performed tensile tests of PEDOT:PSS in three different humidity conditions by nano-UTM, and the results are summarized in Fig. 13. The yield strengths of the samples tested in the lowest humidity environment were greater than those of other samples, and the fracture strain decreased as humidity increased.

In recent years, fingerprint mutual capacitive TSPs with flexible displays fabricated from flexible plastic materials have attracted much attention because of the development of transparent fingerprint sensors embedded in flexible displays that are also thin and impact-resistant. As security protections for electronic devices such as smart phones become increasingly important, a fingerprint sensor has been integrated on the device’s home button because the fingerprint sensor is not transparent. However, a mutual capacitive transparent fingerprint TSP must be developed on the display itself because a wearable device does not have a home button, and the screen sizes of smart devices must otherwise be enlarged.

To make a flexible TSP, a flexible and transparent material must be used for the TSP electrode. However, variation in load becomes a concern when the flexible electrodes of the fingerprint TSP are bent or stretched, which can interfere with capturing the fingerprint image. Because the capacitance difference of the mutual capacitive fingerprint TSP from the ridge to the valley is several hundred atto-farads, the effect of the load variation due to a bent or stretched TSP will be very critical.

Both the flexible fingerprint TSP and post-processing are required to capture the fingerprint image in the fingerprint TSP on the flexible display. A readout IC for the flexible fingerprint TSP is required to distinguish the atto-farad capacitance difference in the fingerprint TSP noise environment on the flexible display. Post-processing is also necessary to compensate for the load variation due to the bent or stretched display.

When the thickness of the covered glass of the flexible display is almost 0.2–0.3 mm, the mutual capacitance difference from the valley to the ridge is almost 50–150 atto-farad. As the thickness of the display panel increases, the mutual capacitance difference is reduced. The thickness of the rigid glass is larger than that of the flexible display panel, which induces a capacitance difference between the valley and the ridge of only several atto-farad.

A low-noise, low-offset, and fast-response receiver is required to acquire a fingerprint image in the mutual capacitive fingerprint TSP on the flexible display. In addition, the post-processing is also required to compensate for the load variation issues that occur because of the flexible TSP’s unique characteristics. A readout IC with high accuracy and a fast response and an effective algorithm for cancelling the offset due to the load variation are both required to achieve an effective fingerprint TSP on the flexible display.

Display products are frequently used for the purposes of task efficiency or leisure. Because long-term and/or frequent use of visual display terminals (VDT) is harmful to our health, ergonomic interventions including ergonomic displays are essential. Users of VDTs suffer from headaches, nausea, visual fatigue, and/or musculoskeletal disorders, which are comprehensively called VDT syndrome or computer vision syndrome. Recently, curved displays have been adopted as a new form of display for several types of commercialized visual display products (smartphones, smart watches, smart bands, TV, and computer monitors). Visual display products that adopt bendable, foldable, or rollable displays are expected in the near future. Existing guidelines for performing visual tasks on flat or convex displays (e.g., ISO 9241) require that characteristics of new displays be evaluated from the perspective of the health of the human user. New types of display are different from conventional displays in terms of optical characteristics, and ergonomic investigations should thus be more focused on visual perception, comfort, and fatigue, among other factors in the ergonomics field.

New forms of display are characterized by optically different properties, which consequently affect visual perception (Fig. 17). Curved displays have been reported to have advantages

When evaluating visual displays, the following measures can be used. Many diverse subjective rating scales are available to assess perceived visual comfort or discomfort, visual fatigue, and cyber-sickness (e.g., ECQ, SSQ). In addition, the concept of presence, or immersive feeling, has become more important as an essential element of a satisfactory viewing experience through any media. Objective measures related to the viewing experience include critical fusion frequency to assess mental stress and visual fatigue, change in pupil size, and eye blink frequency and duration.

It is also important to understand how our visual perception operates to better inform our visual display designs. Related concepts include the just noticeable difference (JND), horopter, and depth perception. For example, JND values for display curvature can be used to determine a specific display curvature within the JND range, within which our perception is regarded equal. The horopter concept contributes significantly to the advantages offered by curved displays in comparison with flat displays. Horopter is “the locus of points in space which project images onto corresponding points in each retina”.

New York, United States, July 19, 2022 (GLOBE NEWSWIRE) -- The global flexible display market had a market share of USD 13.34 billion in 2019, according to the new report of Straits Research. It is predicted to grow at a CAGR of 34.83% from 2022 to 2030. The global flexible display market is expected to grow owing to the rising innovations in consumer electronics and increased demand for a high-quality picture. Integrating smart sensors into residential devices has lengthened the replacement cycle for new consumer electronics. Displays are increasingly being used to control and communicate with devices.

The growing trend of smart homes and buildings and the increasing demand for connected technologies are some of the major factors driving the adoption of connected and innovative solutions across the consumer electronics sector. Effective data storage is becoming critical, with so many viewers consuming media from OTT platforms such as Netflix, Amazon, and others. Thus, the demand for TVs is expected to boost the flexible displays market.

Further, the growing demand for greater picture quality bolsters the demand for flexible displays. The number of 4K televisions sold has increased exponentially in recent years. According to JEITA, the number of 4K TVs shipped in Japan in 2020 will be 3.05 million, up from 2.58 million the previous year. The increase in demand is expected to be driven by the change in resolution and quality of the contents.

Lastly, more exciting and demanding technology, such as virtual reality and 4K displays, is now available. As a result, PC gamers are expected to upgrade their equipment, which is one of the factors driving sales of gaming-specific PCs and their accessories, such as gaming screens. As a result, increased need for picture quality has increased the demand for flexible displays. Report MetricDetails

Due to the global shutdown, production of flexible displays fell precipitously in 2020 due to the global supply chain disruption. COVID-19 had an impact on the operations of not only flexible display manufacturers but also their suppliers and distributors.

In the short term, the failure of export shipments and poor domestic semiconductor demand compared to pre-COVID-19 levels are expected to impact negatively and slightly stagnant demand for semiconductor devices, affecting the flexible display market.

As a result of the ongoing COVID-19 outbreak, several major economies have been placed on lockdown. Sales of electronic products have been hampered, and supply networks have been disrupted. Furthermore, many economies are losing a significant amount of revenue due to manufacturing plant closures. As a result, the general scenario has hampered the demand for flexible displays in 2020.