Category Archives: FPDs and TFTs

Many of the world’s 3D IC elite met last week at the 2nd annual Georgia Tech 2.5D Interposer Conference which focused on the technology and performance of silicon and glass interposers.

Matt Nowak of Qualcomm, long a 3D advocate, reported that Qualcomm has now built "thousands of parts" and does not see anything stopping high-volume manufacturing (HVM) except cost. Nowak indicates that Qualcomm will require a price of ~ $2 for a 200mm2 silicon interposer. The former is just out of the reach of those proposing "coarse" interposer fabrication, and the latter is significantly out of the pricing structure for dual damascene foundry-based fine interposers

Nagesh Vordharalli of Altera quoted an IMEC study which shows that the sweet spot for maximum bandwidth will come from interposers with RDL lines/spaces ~ 3

November 15, 2012 – The LCD TV panel sector closes 2012 with continued tightness due to new process technologies, capacity conversions, a strong market in China, and growing panel sizes. A number of new sizes (39, 50, 58, 60, and 65-in.) enjoyed success and some broke into the mainstream with wide adoption and volume growth.

Looking ahead to 2013, a number of established LCD panel sizes (26, 32, 37, 40-42, 46-47, and 55-in.) will give way to new sizes as TV brands adjust their product mix, calculates NPD DisplaySearch. In a new report, the analyst firm looks at everyone’s 2013 LCD TV panel product mix, and found some big differences between what suppliers offer and what buyers want:

2013 plans for LCD TV set and panel size mix. (Source:
NPD DisplaySearch Quarterly LCD TV Value Chain Report)

While panel makers want to maximize the efficiency of each fab-generation panel size, TV brands are focused on maximizing their market share and revenue. "As panel makers aggressively expand into new sizes, the mismatch is growing more serious," notes Deborah Yang, research director for monitor & TV at DisplaySearch. When the market tightens and push comes to shove, "the push from panel makers is usually stronger than the pull from LCD TV brands," she writes, and "many LCD TV brands will have to adjust their product mixes accordingly.

Here’s her rundown of factors driving that push-pull and how it’ll shake out:

  • Get bigger faster: Panel makers eager to maintain high capacity utilizations (and thus value) have been racing to adopt larger sizes than the TV brands, especially for the biggest sizes (46-60-in. and above).

  • Make bigger cheaper: The very low priced 60-in. set "has changed the ecosystem," Yang writes. Some Chinese TV brands have introduced 58-in. sets to compete with it, while Korea’s Samsung and LG Display are churning out more 60-in. product to compete with Sharp and Vizio. Gen-8 panels are not optimized for that particular size, though, so panel makers are moving to "multi-model glass" from which they can make 60-in and 32-in panels on the same substrate.

  • A shift in smaller panels: Almost everyone (Taiwan, Japan, Korea suppliers) plan to reduce their 32-in. production, which will open the door for Chinese panel makers to grab design wins with international brands.

  • Give a little extra:Most TV brands selling 46/47-in. panels (Panasonic, Philips, Samsung, Sony, Toshiba, Vizio, LG Electronics, and Chinese brands), anticipating a replacement cycle to bigger 50-in. panels, are now adding 50-in. panels.

  • Plug a midsize shortage: A lack of Gen 7 capacity, especially in China, is creating a shortage of 40/42-in. panels. AUO, LG Display, and Chi-Mei Innolux are planning to ramp up 42-in. production in their Gen-8 lines.

  • Move on up: Samsung can add every new size to its product line; Toshiba recently shifted from current mainstream sizes (40, 46, and 55-in.) to new sizes (39, 50, and 58-in.). Sony is considering 42-in. and 39-in. to avoid concentrating too much on 40-in. TV brands in China are coping with a complicated Chinese TV market in which Chinese consumers tend to prefer new products.

by Paula Doe, SEMI Emerging Markets

Materials experts from across the supply chain who gathered at the Strategic Materials Conference 2012 in San Jose in October discussed key materials needs for micromanufacturing outside the CMOS mainstream, as OLEDs and GaN-on-silicon power semiconductors come to market, and alternatives like graphene, CNTs, and self-assembling polymers get closer to commercial application.

Large OLED displays are coming, and counting on materials breakthroughs

OLED adoption in larger displays is surely coming, driven by business necessity, argued James Dietz of Plextronics. Most of the major display makers are seeing operating losses from their LCD business, and OLEDs look like the best option for higher-value, differentiated products to improve margins. The OLED displays look significantly better, and they may potentially open new markets for lighter or flexible or more rugged displays, or for dual-view products. OLEDs’ ultra-fast switching speeds could allow different viewers with different glasses to watch different programs at the same time on the same screen. Moreover, though OLEDs are more expensive now, the variable costs for a 55-in. OLED TV made on an 8G line will be quite comparable to those for a similar LCD. And the OLED costs have far more potential to come down further, by developments like simplifying the layer stack and introducing wet processes that use lower cost equipment with higher utilization of the expensive materials.

But the nature of the market also means new challenges for suppliers. Anxious to avoid another experience like the commoditization of the LCD sector, display makers intend to keep their processes and complex OLEDs materials stacks to themselves this time, which makes process integration of different materials and equipment difficult. The device makers are investing in developing their own materials, making exclusive contracts with equipment and materials suppliers, and doing their own process integration. Integration is also being driven by some materials suppliers like DuPont Displays. But the familiar semiconductor model of the material and tool supplier working together to deliver a process to the customer is not the rule. "We see a gradual transition from all vapor to more solution layers," says Dietz. "OLEDs will enter the TV market in the next three years, and will have solution process steps by 2015."

The 55-in. OLED TVs announced for 2012 now look more likely to come out in only very small volume — a few thousand units in 2012 — and initial prices of ~$9000 will limit sales. But OLED TVs will start to see real growth by 2014-2015, helping to push OLED displays to a $25 billion market by 2017, reports Jennifer Colegrove, VP of emerging display technology at NPD DisplaySearch. She says ten new AMOLED fabs are planned to be built or updated in the next three years. OLED materials, now about a ~$350 million market (include the OLED organic materials but not substrates), should grow at close to the same 40% CAGR of the overall market, to reach $1-2 billion in 2014. But breakthroughs are still needed in oxide and amorphous silicon backplanes, color patterning technology, lifetime of blue materials, encapsulation materials, reduction of materials usage, and of course integration, uniformity and yields of all these things.

OLED display revenues will grow to about $35B in 2019, up from $4B in 2011, with CAGR ~40%. (Source: NPD DisplaySearch, Q3’12 Quarterly OLED Shipment and Forecast Report)

Solution processing is critically important to bringing down the cost of large screen OLEDs, argued John Richard, president, DuPont Displays, as the current production methods which rely on thermal evaporation with fine metal masks are proving costly to scale to 8G substrates. "We developed an alternative process using soluable materials to bring down cost," he notes. Wet processes reduce capital needs and cut material waste to reduce costs significantly, but still need ever better lifetimes and efficiencies of the OLED materials, particularly for blue. A major Asian display maker has licensed the DuPont technology, and plans to scale it up to 8G. The process uses largely pre-existing tools to slot coat the hole injection and transport layers, and pattern the surface with wetting and non-wetting lanes, before nozzle printing stripes of red, green and blue emitters using custom tool developed with Dai Nippon Screen.

The rest of the stack — the electron transfer layer, the electron injection layer, and the metal cathode — is then deposited by thermal evaporation. Richard says coating and printing processes can use significantly less material than vapor deposition, as it avoids losses in the chamber, on the mask, and during alignment and idling. DuPont reports printed blue emitter lifetime is up to 30,000 hours — or 8 hours a day of video for 15 years — before degrading to half brightness. Next issues include optimizing the cost of synthesis and starting materials, and reducing operating voltage for better device efficiency.

Graphene and carbon nanotubes get closer to commercial applications

Next-generation energy storage presents materials opportunities as well. One key enabler for improving both supercapacitors and batteries could be graphene, especially with better sources for consistent quality material at reasonable cost. Bor Jang, CEO of Angstron Materials, reported that his company has engaged a contract manufacturer in Asia to start volume production of as much as 30 tons of graphene next year, using Angstron’s technology that claims good control of structure and properties. "That will bring down costs by an order of magnitude," says Jang. First application will likely be performance enhancers for lithium-ion battery electrode materials, and then for improved electrodes for supercapacitors. Angstron has announced demonstration of a graphene-based supercapacitor with energy density comparable to a nickel hydride battery.

"We think supercapacitors is a market to invest in," said Chris Erickson, general partner at Pangaea Ventures, a somewhat unusual venture fund that invests particularly in materials and green technologies. "We think it will reach $1 billion in the near future." Erickson is also enthusiastic about the potential for dynamic window glazing using vapor-deposited coatings and ITO to adjust to control the shading on windows, for dramatic energy savings of up to 30% in energy consumption in a building, according to NREL — and buildings reportedly use 49% of total energy in the US.

Nantero reported major progress from its long effort in controlled processing and performance for its carbon nanotube thin film, targeting low-cost, low-power non-volatile memory. CTO and co-founder Thomas Reuckes said the company is now lithographically patterning films of its spin-coated aqueous solution of carbon nanotubes, as roughness, adhesion and defectivity are now suitable for semiconductor processing. Metal impurities are down to <1ppb in liquid form, wafer-level trace metals to <1E11 atoms/cm2 . Reuckes reported production of working and yielding 4Mbit CNT memory arrays, and showed results of reliability data. The company just announced a joint development program with imec to manufacture, test, and characterize the CNT memory arrays in imec’s facilities for applications in next generation <20nm memories.

GaN for power semiconductors needs higher purities than LED market

Power semiconductors made on GaN on silicon are being released to the market now, and, given time, could potentially address some 90% of the what IMS Research projects will be a $25 billion (silicon-based) power semiconductor market for MOSFET and IBGTs by 2016, suggested Tim McDonald, VP for emerging technologies at International Rectifier Corp. GaN theoretically offers much better specific on-resistance to breakdown voltage tradeoff than Si or SiC. The key to wide adoption is for GaN on Si based solutions to achieve 2-4× performance/cost compared to silicon.

To achieve the necessary low costs, IR uses compositionally graded layers of AlyGaxN grown on the silicon to ease the thermal and lattice mismatch of the GaN film to the silicon wafer. IR claims 80% yields, with warp and bow controlled enough to run on a standard 150mm CMOS line. GaN on silicon is moving more quickly to market for power semiconductors than for LEDs, as it brings better performance, not just potentially lower prices. It also helps that threading defects do not have the same impact on performance–plus IR has been developing the technology for six or seven years already.

The power market needs higher purity materials and cleaner tools for better yields on its larger die, compared to the LED market. It also prefers larger diameter wafers for lower costs. Demand for gas sources and MOCVD tools should scale with volume, and the tools need to be optimized for larger wafers and become more automated, with perhaps some 2,000-3,000 tools needed for the whole market over the next two decades. Packaging may move from wire bonding to soldered or sintered contacts, and will adopt other means of reducing stray packaging-related inductance and resistance.

The LED market will see only a few more years of significant growth, argued Jamie Fox, lighting and LEDs manager for IMS Research-IHS. Revenues from displays including TVs are leveling off from their fast ramp, as the markets mature, and as LEDs get both brighter and cheaper, driving down both units needed and cost per unit. The LED lighting market will continue its fast climb to near ~$6 billion over the next several years, but then as more lamp sockets are replaced by the longer lasting LEDs (and CFLs), there will be less need for replacements, and the market will slow. Slower adoption near term, however, would mean less saturation later.

Cree’s Mike Watson, senior director of marketing and product applications, countered by pointing out the potential for innovation that solid state technology brings to lighting, noting how digital technology has transformed markets like telephones and cameras into new industries for digital communications and digital imaging. "Semiconductor technology keeps changing industries by innovation," he noted. "Why do we keep thinking of it as just replacement?

Directed self-assembly for higher resolution lines and holes

Another of the more innovative materials alternatives on the CMOS side is directed self-assembly for next-generation patterning, which seems to be making rapid progress. AZ Electronic Materials CTO Ralph Dammel reported that block copolymers, with similar molecules together in blocks instead of randomly dispersed, tended to arrange themselves with the similar chain sections together, conveniently lining up into cylinders that look similar to lithographic contact holes, or into lines similar to lithographic lines and spaces. Wafer surface patterning with topography or chemicals can control the placement of these self-assembled patterns, on top of standard 193nm immersion lithography. Work with IBM Almaden suggests the process can provide better CD uniformity for quadruple patterning at lower cost than the spacer pitch division process. Other work shrinks contact holes, while improving the CD variation compared to the resist prepatterns. The company is now providing large-scale samples for in-fab process learning, with implementation perhaps as early as 2014, though design for self-assembly needs further development work.

November 5, 2012 – In early January of this year, both Samsung and LG showed off 55-in. versions of their organic light-emitting diode (OLED) TVs at the Consumer Electronics Show (CES) in Las Vegas. Commercial volumes were expected on shelves by the time of the 2012 Summer Olympics (which didn’t happen); they were again showed this fall at IFA in Germany.

Unfortunately, still struggling with low manufacturing yields and high prices, the two giants recently admitted the delivery of those technologies will be pushed out into 2013. NPD DisplaySearch now projects only 500 OLED TVs will ship in 2012.

Still, one must crawl before taking first steps and eventually running with the pack. Actually getting products out into the market is an important move, even as LCD TVs continue to get bigger and with higher resolutions. "4K × 2K LCD TVs have has become a focus and are currently available, and OLED TV needs to demonstrate its technical superiority," points out David Hsieh, VP at NPD DisplaySearch. "If we do see OLED TVs hit the market within 2012, the shipments will be used primarily for retail demonstrations in developed regions like North America and Europe."

OLED TV technology still has to overcome a number of obstacles, explained by the research firm:

  • Technical challenges: Making and scaling up large OLED panels (e.g. 55-in.) is a different animal vs. the smaller ones (e.g. 5-in.) now at high-volume output for smart phones.

  • Manufacturing limitations: Only two Gen-8 OLED lines are in place for TV panels, still in pilot mode and with low manufacturing yields which is keeping costs high and limiting the ability to address demand.

  • High price: Initial retail price for a 55-in. OLED will be around $10,000 — that’s not going to cut it when 60-in. LCD TVs sell for under $1000.

  • New high-definition competition: While the two Korean suppliers focus on OLEDs TVs, competitors in Taiwan, China, and Japan are developing LCD TVs with ultrahigh definition (4K × 2K).

  • Market timing: How much advantage do Samsung and LG have from their early adoption of OLED; will competitors quickly close that gap?

NPD DisplaySearch is still bullish on OLED’s longer-term competitiveness, though, expecting that suppliers in Taiwan, China, and Japan will indeed pick up the mantle of AMOLED TV panel production. The firm projects over one million unit shipments in 2014, and a 3% market penetration by 2016.

Forecasted shipments (in millions) and penetration rates for OLED TVs. (Source: NPD DisplaySearch)

 

October 31, 2012 – Applied Materials has announced two new tools for making ultrahigh-definition displays and high-pixel-density screens for mobile devices. One offers a new design for depositing IGZO films for TFTs; the other handles bigger substrates of low temperature polysilicon (LTPS) films to help lower manufacturing costs.

The Applied AKT-PiVot PVD for metal oxide-based thin-film transistors (TFTs) enables a transition from aluminum to copper interconnect bus lines leading to faster pixel response and lower power consumption in LCD TV panels. It overcomes the problem of "mura effect" that reduce display quality, which the company says has hindered metal-oxide technology’s inroads into mainstream LCDs. The "breakthrough" stability of the IGZO films deposited by the tool offers the promise of metal oxide backplanes for OLEDs which would significantly lower their cost as well, the company adds.

(Source: Applied Materials)

A proprietary rotary cathode design employs unique deposition modulation technology to deposit copper layers and form the transistor channel with uniform grain distribution, low resistivity and high thickness uniformity. The technology enables nearly 3× higher target utilization than competitive systems, according to the company, and its rotary targets have >4× longer lifetimes than conventional planar targets.

(Source: Applied Materials)

The Applied AKT-PX PECVD is an extension of the company’s line of PECVD systems to deposit highly-uniform LTPS films on glass substrates. The new tool extends to larger sheets (1.6-5.7m2, or Gen 5 to Gen 8.5 sizes) to help manufacturers increase production and drive down costs, and accelerate the transition of LTPS technology to larger screen sizes for both mobile devices and TVs, the company points out. AMOLED and advanced TFT-LCD displays are switching to the polysilicon-based transistors, which offer higher electron mobility vs. the amorphous silicon (a-Si) used in conventional LCD displays, leading to smaller and faster pixel-controlling transistors, and displays that are brighter, sharper, and use less power — features most desirable for mobile applications.

(Source: Applied Materials)

"The display industry is undergoing one of the most critical technical transitions in the last 20 years — which is being driven by advances in TFT technology," stated Tom Edman, group VP and GM of Applied’s display business group. He added that "customers have reported excellent results with our systems and we already have received multiple orders from major display manufacturers."

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October 30, 2012 – This year is shaping up to be a historically lousy year for makers of flat-panel display (FPD) manufacturing equipment, but expectations are looking up that demand will catch up to supply in 2013 and balance the market, according to NPD DisplaySearch projections. Spending on FPD equipment is projected to plummet -69% in 2012 to $3.8 billion, making it the worst year in the sector’s history. But even with slow demand growth in maturing markets (TVs and PCs), the firm sees "significantly improved conditions" in 2013, more than doubling to $8.3B.

Most of that spending will be for new low-temperature polysilicon (LTPS) fabs or converting existing amorphous silicon (a-Si) capacity to LTPS, both for use in TFT-LCD and active-matrix OLED (AMOLED) production, explains Charles Annis, VP of manufacturing research at NPD DisplaySearch. "One reason spending is increasing so much is because LTPS fabs cost substantially more than a-Si fabs to build. There are extra process necessitate more than 10 mask steps." LTPS fabs also require higher-priced equipment, particularly high-resolution photolithography tools, he added, but having those technologies does enable production of high-value displays used in smartphones and tablets.



FPD equipment spending forecast. (Source: NPD DisplaySearch)

Such dramatic cutbacks in investment will more quickly rebalance supplies with demand and raise fab utilization rates. Meanwhile, new manufacturing technologies (oxide semiconductors, in-cell touch, flexible AMOLEDs and AMOLED TVs) promise lower costs and higher-value applications. Together that spells improve profitability for panel makers, notes Annis. Even with the cautionary disclaimer that new investments (e.g. AMOLED capacity) can be pushed out or cancelled if performance and cost targets don’t materialize, most of the firm’s indicators project 2013 "to be a much better year than 2012."

October 24, 2012 – Several trends are helping to steer the flat-panel display industry back on the road to recovery, despite excess capacity and eroding prices (and profits). One is the commercialization of advanced technologies and specifications (e.g. higher resolution, wider viewing angels, integrated touch functionality, and slimmer/lighter formfactors). The other is a shift toward larger panel sizes.

“The average diagonal sizes of key FPD applications have increased over the past three years, and every inch of growth in flat panel display applications results in growth in area demand and thus capacity utilization,” points out David Hsieh, VP of Greater China Market Research for NPD DisplaySearch. Consumers won’t want to go back to smaller displays and lower resolutions, so average (diagonal) sizes will accelerate in 2013, spurring long-term growth for the entire flat-panel display industry. DisplaySearch notes that LCD TV panel sizes have increased 2 inches in just the past 12 months (August 2011-August 2012), from 34.8-in. to 36.8-in.. Sharp, which has the highest average screen size of TV panels shipped, has added nearly 10-in. to its panels (39.1-in. to 48.3 in). Given a total typical 18-20M panel shipments/month, those extra sizes add up quickly.

Here’s DisplaySearch’s tracking of multiple key FPD applications and their size differences over a four-year period. Note mobile PCs are actually seeing smaller screen sizes thanks to the rise of tablets and ultrabooks. The firm also notes "challenges" for desktop panels in 2012-2013 as due to PC bundles and fewer standalone PC replacements, though consumers are splurging on bigger LCD monitors (23-in. to 27-in.).

Average diagonal size of key FPD applications, in inches. (Source: NPD DisplaySearch)

What’s behind the increase in screen sizes? Consumers, given the choice, are choosing bigger: 26W to 29 W, 37W to 39W, 46/47 to 50-in, 55 to 60-in. That includes when they upgrade older LCD TVs. Consumers in North America have been upgrading their living room sets from 40-in. to 50-in. or bigger, and from 32-in. to 39-40 in the bedroom, DisplaySearch notes. And for TV firms, larger-sized TVs mean bigger profit margins.

DisplaySearch says to watch for some major holiday promotions around bigger LCD TVs. (Rumor has it there’ll be a Black Friday deal of $999 for a 60-in. LCD TV.) This should keep whetting consumers’ appetites to keep migrating to bigger screens, perpetuating the trend of making the bigger panels.

October 18, 2012 – Worldwide flat-panel display (FPD) revenues will reach a record $120 billion in 2012, up 8% from a challenging year in 2011, and the recovery is entirely on the backs of TFT-LCDs and AMOLED displays, according to NPD DisplaySearch.

TFT-LCD displays still make up the vast share of all display sales (~90%), and so the overall market tracks in-step with this segment, rebounding from a -5% decline in 2011 to an 8% rise in 2012. Note, though, that of all the other display technology slices, AMOLEDs have by far the best growth trajectory — two years ago it was fourth in total market share (1%) behind plasma, passive matrix, and roughly tied with CRT; now it’s the second-most-popular display technology with a 5.4% share and the gap is widening. Credit surging manufacturing capacity and expansion of market players, DisplaySearch says. The only other segment to see any growth is liquid crystal on silicon (LCOS) used for microdisplays. Also note the sharp rise and sharper plummet of active-matrix electrophoretic displays (AMEPD), used in monochrome e-reader devices, which are giving up ground to TFT-LCD tablet PCs.

Worldwide FPD revenues by technology, 2010-2012. (Source: NPD DisplaySearch)

2011 was a tough year for displays due to price erosion in TFT-LCD panels, particularly for TV applications, DisplaySearch notes. The rebound in 2012 has many factors behind it: bigger average sizes and shipments of LCD TVs, higher prices for high-resolution mobile displays, strong unit growth for tablet PCs, expansion of AMOLED shipments and applications, thinner and lighter ultraslim notebook PC panels, the emergence of 4k × 2k LCD TVs, and demand for a number of applications including games, car navigation systems, and digital signage.

"While the industry faces challenges in traditional applications such as plasma TVs and mainstream sizes of LCD TVs and desktop monitors, the addition of new features and lower prices are driving growth of applications such as tablet PCs and smartphones," explained David Hsieh, VP at NPD DisplaySearch.

The outlook for the FPD industry isn’t entirely cloud-free: there’s a lot of saturation in several major markets, Hsieh noted. Nevertheless, the supply chain is figuring out how to "increase the value proposition" of FPDs by emphasizing their technology improvements: higher resolution for mobile devices, bigger screens, thinner and lighter versions for mobile PCs, improved wide-viewing angle, and desirable functionalities like touchscreen. "We expect 2013 to be a good year for the FPD industry, with revenue increasing, as TFT LCD prices recover and AMOLED demand grows," Hsieh said.

September 25, 2012 – Linde Electronics, a unit of the Linde Group, has added a new high-purity nitrous oxide (N2O) plant in Zhenjiang, Jiangsu Province, China to help support increased adoption of metal oxide transistors by display manufacturers.

The new plant follows an expansion of a plant in Taiwan and another one being built in Korea; the two plants in China will be managed by Linde LienHwa, a joint venture with LienHwa MiTAC Group in Taiwan. Linde and LLH are currently running six N2O plants in Asia with a capacity of more than 3,000 tons per year; the three new plants will boost design capacity to more than 10,000 tons per year.

Improving electron mobility in transistors is crucial in bringing higher resolutions and higher frame rates to TVs, mobile and computing devices. Making next-generation ultrahigh-definition 3D TFT/LCD and OLED displays is currently expensive, requiring the use polysilicon transistors which cost twice as much as those using amorphous silicon. Replacing polysilicon with metal oxide can increase electron mobility by a factor of up to 40 compared with conventional technology, at a comparable cost. Metal oxide transistor manufacturing requires high volumes of high-purity N2O to create functional layers of the microscopic thin-film transistors required to control each of the millions of pixels that make up the visible image.

The metal oxide transistors also allow more light to pass from the backlight through the backplane, reduce power consumption, and increase battery life of mobile devices. Moreover, they also allow the higher currents needed to drive OLEDs. Most display makers have or are working on products with metal-oxide transistors — Samsung and LG both have 55-in. OLED TVs, and Sharp has begun commercial production of metal oxide displays in its Kameyama plant.

"The shift from silicon to metal oxide transistors would not be possible without a secure supply of high-purity N2O, which highlights the critical role that specialist gases play in enabling the development of next-generation consumer electronic devices," stated Andreas Weisheit, head of market development for flat-panel displays at Linde Electronics.

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September 25, 2012 – A three-year European project to research solution-processable materials for OLEDs has concluded, with newly developed materials that can be integrated into large-surface OLED components and are suited for printing processes.

The NEMO (NEw Materials for OLEDs from solutions) project, a consortium of 11 companies led by Merck, was formed in Nov. 2009 with backing from the German Federal Ministry of Education and Research (BMBF), to explore a variety of OLED materials and capabilities: soluble light-emitting materials, charge transport materials, new adhesives for reliable encapsulation of each OLED component. Physical tests were included to understand more about the materials for future development work. The project’s total budget was €29M (roughly US $38M).

"The success of the project is an enormous and important step for printable material systems with very good performance data," stated Dr. Udo Heider, head of the OLED unit at Merck. "We are enabling our customers to use cost-efficient manufacturing processes, which thanks to their low material losses in production, will ultimately also benefit the environment."

Results of the project include Merck’s development of a new phosphorescent materials for red, green and blue applications — increasing lifetime extrapolated to 50% of initial brightness (i.e., stability in use) of green triplet emitter materials from 10,000 hours to more than 200,000 hours, and increasing the efficiency of these materials from 30 cd/A up to more than 70 cd/A (candela/ampere) at a brightness of 1000cd/m2.

Here’s a list of other results achieved by the NEMO project’s four industry companies and seven research institute/academic groups:

Humboldt University of Berlin: Modular synthesis strategies were used to produce and test new electron transport materials.

DELO Industrie Klebstoffe: Development of adhesives with low water vapor permeation for flat encapsulation. A main focus of the work was on optimizing the compatibility of the adhesive with the OLED materials. Suitable adhesive systems were identified, and a significant reduction in component defects was achieved. The developed systems were extensively characterized.

Enthone GmbH (formerly Ormecon): Developed dispersions of polyaniline, an electrically conductive polymer, from which charge carrier layers for OLEDs were produced. These displays show electrical properties equivalent to those of the previously used material. For OLED component characterization, impedance spectroscopy was used to investigate the OLEDs prepared by Merck. It was possible to identify unstable areas, which are responsible for the short lifetimes of OLEDs. Additionally, the impedance measurements were used to predict the lifetime of displays.

Fraunhofer Institute for Applied Polymer Research (IAP): Developed polymer-based phosphorescent systems for green and red Merck emitters. Suitable charge transport molecules were bonded as a side group to a main polymer chain. It was possible to demonstrate that this leads to comparable or even better performance parameters and lifetimes of OLEDs in comparison with solution-processable small molecules. For "green", energy efficiencies of 61 cd/A and lifetimes of 66,000 h @ 1000 cd/m2 were achieved.

Heraeus Precious Metals GmbH & Co. KG (formerly H.C. Starck Clevios GmbH): Developed new materials for the intermediate layers, which will improve the charge carrier injection from the anode into the OLED emitter layer and help to increase the lifetime of the components. The work function of the hole injection layers can be set to a specific target value within a wide range of 4.8-6.1 eV. Water-soluble polymer counterions have been developed, which have helped to realize dehydrated PEDOT materials for the first time.

In parallel to this, work was conducted on transparent electrodes that can be separated from solution and are expected to lower the costs of OLEDs. The conductivity of the PEDOT:PSS films was further increased. Initial ITO-free OLED lamps have been realized. In combination with screen printed silver lines, this enables the production of OLEDs for lighting application without any identifiable decrease in luminance from the edge to the center of the component.

University of Potsdam: Studied physical properties such as charge carrier transport and excitation dynamics in newly synthesized materials and in the finished component. In combination with stationary and transient simulations, information was obtained on what processes restrict the efficiency of light emitting diodes and which ones impact component aging.

University of Regensburg: One working group, led by Professor Yersin, developed new emitter classes with both strong and weak metal-metal interactions that show a singlet harvesting effect. It is thus possible to realize highly efficient emitters for OLEDs based on highly economical copper clusters. This work on singlet harvesting with newly developed emitters made from copper clusters was recognized in April 2012 with an innovation prize at the international SPIE Organic Photonics conference in Brussels.

Another working group (led by Professor König) synthesized emitter libraries in accordance with a simple combinatorial protocol. A screening system was developed for the rapid and virtually automated identification and characterization of individual emitters as well as photostability testing thereof. This made it possible to investigate the degradation behavior of many substances and to draw conclusions on various degradation mechanisms.

University of Tübingen: Two groups from Tübingen provided new metallorganic cluster compounds that can be used as luminescent molecules in OLEDs. In chemical synthesis, coordination compounds of the metals rhodium, iridium, palladium, platinum, copper, silver and gold were presented and characterized, giving rise to new, highly promising lead structures for emitter materials.