Category Archives: Displays

The 2019 FLEXI Awards has recognized outstanding accomplishments in the Flexible Hybrid Electronics (FHE) industry in 2018. Presented yesterday at the 18th annual FLEX 2019 Conference and Exhibition in Monterey, California, the awards spotlight leaders in the categories of R&D Achievements, Product Innovation and Commercialization, Technology & Education Leadership, and Industry Leadership.

R&D Achievement Award Recipient – FLEXI winner FlexEnable developed the world’s first industrially-proven, low-cost flexible transistor technology, allowing displays to be built on plastic. Now entering mass production, this organic LCD (OLCD) technology will soon be used in displays for applications including Smart home appliances, automotive and digital signage.

“We are honored to receive this prestigious award for FlexEnable’s groundbreaking plastic organic LCD (OLCD) technology,” said FlexEnable CEO Chuck Milligan. “The award comes at a very exciting time for the company as OLCD enters mass production to deliver a new freedom in product design and novel display applications.”

Product Innovation Award Recipient – American Semiconductor won the FLEXI for the innovative product design of FleX NFC, the industry’s first flexible IC to support NFC communication and new ways to connect to the Internet of Things (IoT).

“We sincerely appreciate this recognition from SEMI-FlexTech and are excited about collaborating with our Semiconductor-on-Polymer Chip Scale Packaging customers,” said Richard Ellinger, VP of Sales and Marketing of American Semiconductor. “Our high-functioning, zero-profile, flexible, durable ICs will enable Smart products in 2019 and beyond.”

Technology Champion & Leadership in Education Award Recipient – Mark Poliks, Empire Innovation Professor of Engineering and Director of the Center for Advanced Microelectronics Manufacturing at Binghamton University, won a FLEXI for advancing flexible and printed electronics and for his contributions to the FLEX conference including participating in Calls for Abstracts, leading a Tech Course, and serving on every SEMI-FlexTech committee.

Molecular Lego blocks


February 15, 2019

Producing traditional solar cells made of silicon is very energy intensive. On top of that, they are rigid and brittle. Organic semiconductor materials, on the other hand, are flexible and lightweight. They would be a promising alternative, if only their efficiency and stability were on par with traditional cells.

Together with his team, Karsten Reuter, Professor of Theoretical Chemistry at the Technical University of Munich, is looking for novel substances for photovoltaics applications, as well as for displays and light-emitting diodes – OLEDs. The researchers have set their sights on organic compounds that build on frameworks of carbon atoms.

Both the carbon-based molecular frameworks and the functional groups decisively influence the conductivity of organic semiconductors. Researchers at the Technical University of Munich (TUM) now deploy data mining approaches to identify promising organic compounds for the electronics of the future. Credit: C. Kunkel / TUM

Contenders for the electronics of tomorrow

Depending on their structure and composition, these molecules, and the materials formed from them, display a wide variety of physical properties, providing a host of promising candidates for the electronics of the future.

“To date, a major problem has been tracking them down: It takes weeks to months to synthesize, test and optimize new materials in the laboratory,” says Reuter. “Using computational screening, we can accelerate this process immensely.”

Computers instead of test tubes

The researcher needs neither test tubes nor Bunsen burners to search for promising organic semiconductors. Using a powerful computer, he and his team analyze existing databases. This virtual search for relationships and patterns is known as data mining.

“Knowing what you are looking for is crucial in data mining,” says PD Dr. Harald Oberhofer, who heads the project. “In our case, it is electrical conductivity. High conductivity ensures, for example, that a lot of current flows in photovoltaic cells when sunlight excites the molecules.”

Algorithms identify key parameters

Using his algorithms, he can search for very specific physical parameters: An important one is, for example, the “coupling parameter.” The larger it is, the faster electrons move from one molecule to the next.

A further parameter is the “reorganization energy”: It defines how costly it is for a molecule to adapt its structure to the new charge following a charge transfer – the less energy required, the better the conductivity.

The research team analyzed the structural data of 64,000 organic compounds using the algorithms and grouped them into clusters. The result: Both the carbon-based molecular frameworks and the “functional groups”, i.e. the compounds attached laterally to the central framework, decisively influence the conductivity.

Identifying molecules using artificial intelligence

The clusters highlight structural frameworks and functional groups that facilitate favorable charge transport, making them particularly suitable for the development of electronic components.

“We can now use this to not only predict the properties of a molecule, but using artificial intelligence we can also design new compounds in which both the structural framework and the functional groups promise very good conductivity,” explains Reuter.

By Mike Russo

For public policy lovers, civic-minded, engaged U.S. citizens, and people around the world interested in the U.S. President’s positions and priorities, the annual State of the Union address (SOTU) is “must-see TV.” This year, the anticipation and expectations were different than with past presidents. Trump is the first U.S. president who has used social media to the extreme that he has. Indeed, his Twitter feed is the most followed in history.

President Trump’s prolific Twitter feed has had an interesting impact on the SOTU. U.S. citizens and people from around the world already know President Trump’s positions on issues, his policy priorities and what gets him excited. There is an ongoing, direct line to the President’s thoughts throughout each and every day. In the past we looked to the SOTU for insights into what the sitting president is really thinking and his future policy priorities. Now, there isn’t much we don’t already know.

One looming question this year was whether President Trump would reach out in a conciliatory manner to help bridge the political divide and lay the groundwork to enable some public policy wins and avoid another government shutdown. While there were moments of conciliation, the President made it clear he would not move on areas that are most contentious with the other side of the aisle.

For example, the President unequivocally reiterated his intent to build “the wall.” While the message plays well to his base, it is, in effect, a frontal assault and challenge to Democrats. It’s hard to image that his staunch stance will help move the two parties to work together on substantive policy issues. It may also mean that the “wall” issue will occupy lawmakers time for the foreseeable future, sidelining debate on other important issues.

The best hope is that a bipartisan bill finds its way to the President’s desk that he can sign and use to “declare victory.” However, many political observers believe the likelihood of the President declaring a national security emergency is rising as a maneuver to ensure funding for “the wall” and avoid a shutdown. While such a declaration would most likely face a court challenge, the President could claim that his decision was a move of last resort and leverage the moment to position Democrats as obstructionists to his base. The scenario does not bode well for the bipartisan support necessary to address other issues.

What does this mean for our industry? Were there any points raised in the SOTU that would signal a change in what we are facing regarding trade, tariffs, export controls and immigration? Were any new issues or ideas raised that could help lift the global economy? In short, no. On one hand, the President cited his good relationship with the president of China, but on the other doubled down on his attacks on China, seeming to stand firm to bolster his position at the table as the U.S. and China trade talks continue.

What do these dynamics mean for SEMI Global Advocacy? In 2018 we were heavily engaged in efforts to prevent regulations that would inhibit our members’ ability to develop and deploy technologies and maintain global market access. We advanced our global advocacy model, leveraging our regional presence around the world. Many of the potential issues we faced emanated from the U.S., including those focused on controlling technology development, limiting trade and enhancing export controls. We also intensified our efforts to address industry talent pipeline issues.

In 2019, our public policy focus will be to continue to push back on tariffs, engage members to inform the rule-making process for export controls and to attempt to influence the immigration debate as it pertains to access to talent. In addition, while the U.S. R&D tax credit was made permanent through the tax cut in 2017, some of the provisions may have unintended consequences and will need to be modified. How the law is enacted will affect how businesses can deduct qualified research and development and other expenses from their taxable income, so we anticipate activity on the tax front as well.

It will also be a big year for SEMI on the workforce developmentfront. SEMI will continue to grow its existing High Tech U (HTU), university and mentor programs. In addition, SEMI will be positioning itself as the global leader in addressing issues related to the talent pipeline by approaching the problem with a full-spectrum, holistic approach that is intended to better address more immediate needs in attracting, training and retaining qualified talent. We’ll also focus on improving the industry image and exciting students at a younger age by providing experiential learning activities throughout a defined educational pathway. Stay tuned on this front as the full program unfolds.

In general, we will continue to build our relationships and stature as a leading voice for our members and the end-to-end semiconductor supply chain in the areas of “Talent, Trade, Tax and Technology” (SEMI’s “4 Ts”) and to ensure free and fair trade, access to markets, supply chain growth, IP protections and enhanced efforts to improve cybersecurity.

Mike Russo is VP of Global Industry Advocacy at SEMI. 

Source: SEMI Blog

By Maria Vetrano

With over 25 years of experience in the technology industry, Sri Peruvemba, CMO of CLEARink Displays, is a longtime advocate of electronic display technology. During his presentation at FLEX and MEMS & Sensors Technical Congress 2019, February 18-21 in Monterey, Calif., Peruvemba will explain recent innovations in electronic paper (ePaper) that will open new applications to reflective displays for the first time.

SEMI: ePaper has been around for more than a decade. How has it evolved for wearables and mobile devices?

Peruvemba: ePaper in its current form provides a reflective display that is low power and sunlight-readable to applications such as eReaders and electronic shelf labels (ESLs), both of which are in mass production. There is a much larger opportunity, however, for reflective displays that offer color and video atop the traditional benefits of ePaper. Now possible through electrophoretic total internal reflection (eTIR) – which we have termed ePaper 2.0 – is a low-power technology that allows devices to work for days instead of hours. eTIR offers sunlight readability as well as full color and video-level switching speeds, which satisfies the diverse requirements of wearables and mobile devices.

New electrophoretic total internal reflection (eTIR) display technology uses the charged particles in a fluid to modulate the total internal reflected light from the optical structures incorporated into its novel reflector film. Image courtesy of CLEARink Displays.

SEMI: How do you define a “reflective display?”

Peruvemba: A display that reflects external light to its advantage is a reflective display. This includes the display that uses ambient light rather than a backlight and one that uses the sun rather than fights it.

SEMI: Where is there a larger opportunity for reflective displays that offer color and video over the traditional benefits of ePaper?

Peruvemba: While most of us are familiar with ePaper in applications such as eReaders and wearables that need sunlight readability, there is an untapped market in the wearables space for applications that require internet browsing and color, even video, displays. ESLs are a good example. Retailers are no longer content to show prices. They also want to show specials, display color ads, and run video and animation to enhance product differentiation. Displays in tablets, digital signage and automotive are additional targets.

SEMI: How large is the opportunity?

Peruvemba: The electronic display industry has been trying to build reflective displays that are low-power color and video for many years but without success. Hence, the opportunity is in the tens of billions of U.S. dollars in outdoor signs, automotive displays, tablets, wearables, shelf labels and dozens of others products.

SEMI: What will it take for manufacturers to migrate from LCD or OLED to eTIR?

Peruvemba: The good news is that implementation is pretty much the same as with the LCD or OLED displays currently in use. The interfaces, connections and form factors remain form-, fit-, function-compatible. Only the software/waveforms and drive voltages will change/reduce. This allows the manufacture of our tech., ePaper 2.0, on the old LCD lines that are already in use. You can literally go back and forth between ePaper 2.0 and LCD on a day-to-day basis. This differs from other eTIR implementations, which require new dedicated manufacturing lines that cost tens to hundreds of millions of dollars.

SEMI: Are there other emerging markets that are particularly well-matched to eTIR?

Peruvemba: Tablet devices designed for long use on a single charge, mobile devices including wearables for outdoor applications, Internet of Things (IoT) devices that need high ambient readability, and very low-power and unobtrusive displays in home or office settings represent other emerging markets.

SEMI: What technical obstacles have hindered ePaper in certain markets – and how do you overcome those obstacles?

Peruvemba: Bringing a display technology to market is not only about solving technical and process hurdles. It is also about finding the right one percent of the applications that your technology can uniquely address. Success requires developing the ecosystem of subcomponent suppliers and peripheral technology providers (like touch and front lights). Partnering with the display fabs that can mass-produce your technology is another important step.

With most emerging technologies, the pursuit of the right customer is the bigger challenge, but for us it has been getting the product into production. Fortunately, we already have customers that have invested in the company and have committed to product volume, so they get early access to our technology.

SEMI: What would you like FLEX and MSTC attendees to take away from your presentation?

Peruvemba: Now just months away from deploying our eTIR technology as ePaper 2.0, we welcome partnership inquiries as we seek to implement eTIR across a range of previously unserved and underserved display markets.

Sri Peruvemba will present ePaper 2.0 — Creating New Markets at FLEX/MSTC on Tuesday, February 19 at 2:45 pm

Register today to connect with him at the event. To learn more about CLEARink Displays, click here.

MSTC FLEX 2019 is organized by MEMS & Sensors Industry Group (MSIG) and FlexTech.

Leti, an institute of CEA-Tech, has developed a novel retinal-projection concept for augmented reality (AR) uses based on a combination of integrated optics and holography. The lens-free optical system uses disruptive technologies to overcome the limitations of existing AR glasses, such as limited field-of-view and bulky optical systems.

TVs and smartphones that project digital images emit light all around them, as quasi-isotropic sources. Because the images are projected generally over the air without directivity, many viewers see the same image. In typical AR glasses, images are transmitted close to the eyes (high directivity) by a microdisplay that includes an optical system and an optical combiner.

These microdisplays create a small near-to-eye image, which is transformed by the optical system, enabling the user to see it despite the short focusing distance. The combiner superimposes the digital image to the viewers’ vision of the real environment.

CEA-Leti’s innovation is a transparent retinal-projection device that projects various light waves to the eyes from a glass surface. Images are formed in the retina by the interference of light waves, which eliminates the need for optical systems or combiners. The light propagating in the air doesn’t form an image until it interferes precisely in the retina.

CEA-Leti presented its results Feb. 6 at SPIE Photonics West 2019 in a paper titled “Integrated Optical Network Design for a Retinal Projection Concept Based on Single-Mode Si3N4 Waveguides at 532 nm”.

The project focused on the design and numerical simulations of integrated Si3N4 optical components and the optical circuit at λ = 532 nm. It required building blocks for designing an optical integrated circuit capable of creating an array of emissive points. Starting with single-mode waveguides to efficiently transport light around the circuit, many other components were designed to manipulate light in different locations. Components for extracting the light, such as diffraction gratings, were also designed and simulated. The team minimized losses of different parts of the circuit, such as waveguide-bending areas, to increase energy efficiency of the system.

CEA-Leti’s integration of the device and its use of a holographic layer also allow creation of compact AR glasses with a larger field-of-view than existing systems, while the transparent retinal projection device allows ambient light to pass through the device for enhanced AR applications.

“Combining integrated optics and holography is a new research area for the scientific community developing display applications,” said Basile Meynard, a Ph.D. student and lead author of the paper. “It is also a way to imagine a display device that works more as a data transfer system than as an imaging system.”

The novel approach will require further development before it reaches the commercialization stage. In the medium to long term, the retinal projection concept is expected to support more compact and higher virtual-image quality applications similar to existing AR glasses.

This research project builds on CEA-Leti’s many years of development of micro-displays for near-to-eye displays, such as organic LED technologies (OLED) and liquid crystal devices (LCD). More recently, the institute has made significant strides in the field of inorganic LED display manufacturing.

“Our teams are continuously looking for potential disruptive technologies that could pave the way to new families of display devices down the road,” said Christophe Martinez, optical senior scientist and project leader in Leti. “The investigation on retinal displays is part of this exploration of future optical solutions.”

The intelliFLEX Innovation Alliance announced today that Mark Majewski, a 30-year veteran of the Canadian technology industry and former geographic director at a major semiconductor company, has succeeded Peter Kallai as CEO.

Mr. Majewski has extensive experience in the electronics and technology industries in Canada, having overseen the generation of hundreds of millions of dollars at STMicroelectronics while running its East Central U.S. and Canada regions. He’s also been a key leader at several startups, volunteers as a mentor at the RIC Centre and Haltech, and most recently was the technology lead for business development at Ontario Centres of Excellence (OCE).

Mr. Majewski’s goal as CEO is to unite the growing critical mass of Canadian printable, flexible and hybrid electronics (FHE) companies and research with the country’s electronics and semiconductor industries. With his decades of technology experience, Mr. Majewski has the breadth of contacts, experience, and knowledge to successfully position intelliFLEX and its members alongside this massive industry.

“I’m honoured to have been named the next intelliFLEX CEO. I’ve taken this role because I believe in FHE and its future,” says Mr. Majewski. “All electronics players in Canada who want to expand their capabilities should be looking at this technology as it goes mainstream. Not only does FHE open the doors to new products and applications, it also has incredible value in augmenting and improving everyday electronics products that already exist.”

Indeed, as microelectronics and semiconductor companies hit the limits of Moore’s Law for integrated circuits, mainstream companies are searching for new ways to produce electronic components more efficiently for new and existing applications.

That’s where printable, flexible and hybrid electronics come in: FHE, which represents a $31.6B global market opportunity, uses next-generation additive and manufacturing electronics technologies that can help all electronics players in Canada. This strategy has already been embraced in the U.S. where a cross-pollination of mainstream electronics, FHE, and semiconductors is occurring.

“I’ve cherished the opportunity to work with intelliFLEX,” said outgoing CEO Peter Kallai, who founded intelliFLEX and will remain involved by supporting Mr. Majewski during the transition period and sitting on the board of directors. “However, what we need to do is move the organization into the mainstream electronics industry and be the rising tide of the ecosystem that lets all our members sail further, faster and easier.

“We needed a professional from that industry, with the right background, to do that. And I strongly believe Mark will take intelliFLEX to the next level.”

At the same time, intelliFLEX will also move its head office from Ottawa to the Greater Toronto Area. This will help the organization be physically closer to the heart of Canada’s electronics industry, of which the majority is located in Toronto. Seventy-five per cent of intelliFLEX members are in either Ontario or Quebec.

SEMI-FlexTech, an industry-led, public/private partnership, today issued a Request for Proposals (RFP) for artificial intelligence (AI), Human-Machine Interface (HMI), sensor system and other projects to advance the flexible hybrid electronics (FHE) ecosystem. Approximately $5 million is allocated for these projects. Manufacturers and developers in the electronics supply chain are encouraged to respond to the SEMI-FlexTech 2019 RFP. Primary funding will be provided by the U.S. Army Research Laboratory (ARL) through SEMI-FlexTech.

Topics in this 2019 Solicitation are:

  1. Reference designs for FHE sensor systems
  2. FHE Power
  3. Artificial Intelligence (AI) for additive manufacturing
  4. Mixed mode interconnect and metallization for FHE
  5. Human-Machine Interfaces (HMI)
  6. Open concepts for sensor and FHE technologies and agile, expedient manufacturing

Details about each topic are included in the full RFP.

SEMI-FlexTech’s R&D program focuses on developing the infrastructure required to support world-class manufacturing capabilities for FHE devices and products. Because flexible and printed electronics development often requires expertise across multiple disciplines including printing, materials science and advanced semiconductor packaging, SEMI-FlexTech prefers multi-institutional teams. Participation of organizations new to the SEMI-FlexTech program is especially welcome.

The program is designed to support more risky technical approaches, as well as those proposing step improvements to current technology. The proposal process consists of two stages:

  1. White paper submission
  2. Submission of full proposal from respondents selected after white paper review

White papers will be accepted until March 1, 2019, at 5:00 p.m. PST. Full proposals will be due by April 15, 2019, and award notifications will be issued on or about June 1, 2019.

“SEMI-FlexTech is excited to again partner with ARL in advancing the flexible electronics industry,” said Dr. Melissa Grupen-Shemansky, SEMI CTO for flexible electronics and advanced packaging. “The topics provided are a rich set of technology initiatives that will appeal to many of our members.”

SEMI-FlexTech and ARL personnel will be available for consultation at FLEX 2019 in Monterey, California, February 18-21, 2019.  A webinar for those interested in learning more will be held on Friday, February 8, 2019, at 10:00 a.m. PST.

Researchers at the University of Exeter have developed an innovative technique that could help create the next generation of everyday flexible electronics.

A team of engineering experts have pioneered a new way to ease production of van der Waals heterostructures with high-K dielectrics- assemblies of atomically thin two-dimensional (2-D) crystalline materials.

One such 2-D material is graphene, which comprises of a honeycomb-shaped structure of carbon atoms just one atom thick.

While the advantages of van der Waals heterostructures is well documented, their development has been restricted by the complicated production methods.

Now, the research team has developed a new technique that allows these structures to achieve suitable voltage scaling, improved performance and the potential for new, added functionalities by embedding a high-K oxide dielectric.

The research could pave the way for a new generation of flexible fundamental electronic components.

The research is published in the journal Science Advances.

Dr Freddie Withers, co-author of the paper and from the University of Exeter said: “Our method to embed a laser writable high-K dielectric into various van der Waals heterostructure devices without damaging the neighbouring 2D monolayer materials opens doors for future practical flexible van der Waals devices such as, field effect transistors, memories, photodetectors and LED’s which operate in the 1-2 Volt range”

The quest to develop microelectronic devices to increasingly smaller size underpins the progress of the global semiconductor industry – a collection of companies that includes the tech and communication giants Samsung and Toshiba – has been stymied by quantum mechanical effects.

This means that as the thickness of conventional insulators is reduced, the ease at which electrons can escape through the films.

In order to continue scaling devices ever smaller, researchers are looking at replacing conventional insulators with high-dielectric-constant (high-k) oxides. However, commonly used high-k oxide deposition methods are not directly compatible with 2D materials.

The latest research outlines a new method to embed a multi-functional, nanoscaled high-K oxide, only a within van der Waals devices without degrading the properties of the neighbouring 2D materials.

This new technique allows for the creation of a host of fundamental nano-electronic and opto-electronic devices including dual gated graphene transistors, and vertical light emitting and detecting tunnelling transistors.

Dr Withers added: “The fact we start with a layered 2D semiconductor and convert it chemically to its oxide using laser irradiation allows for high quality interfaces which improve device performance.

“What’s especially interesting for me is we found this oxidation process of the parent HfS2 to take place under laser irradiation even when its sandwiched between 2 neighbouring 2D materials. This indicates that water needs to travel between the interfaces for the reaction to occur.”

Global shipments of large thin-film transistor (TFT) liquid crystal display (LCD) panels rose again in 2018 despite concerns of over-supply in the market. In particular, area shipments increased by 10.6 percent to 197.9 million square meters compared to the previous year, driven by TV and monitor panels, according to IHS Markit (Nasdaq: INFO).

Fierce price competition in large 65- and 75-inch display panels was ignited as Chinese panel maker BOE started the mass production of the panels in 2018 at its B9 10.5-generation facility. “With BOE operating the 10.5-generation line, panel makers have become more aggressive on pricing since early 2018 to digest their capacity,” said Robin Wu, principal analyst at IHS Markit. “Large panels are still more profitable than smaller ones.”

Rising demand for gaming-PC and professional-purpose monitors boosted shipments of high-end, large panels. “Some panel makers have allocated more monitor panels to the fab, replacing existing TV panels, to make up for poor performance of that business,” Wu said.

Demand for other applications, which include public, automotive and industrial displays, recorded the highest growth rates of 17.5 percent by area and 28.6 percent by unit. “Panel makers view these applications as a new cash cow that can compensate for the sharp price erosion in main panels for TVs, monitors and notebook PCs,” Wu said.

LG Display led the area shipments of large display panels, with a 21 percent share in 2018, followed by BOE (17 percent) and Samsung Display (16 percent). BOE boasted the largest unit-shipment share of 23 percent, followed by LG Display (20 percent) and Innolux (17 percent), according to the Large Area Display Market Tracker by IHS Markit.

Large TFT LCD panel shipment growth is expected to continue in 2019. The preliminary forecast for unit shipments of three major products indicates that panel makers will continue to focus on the monitor and notebook PC panel businesses, increasing shipments by 5.3 percent and 6.6 percent, respectively, over the year, while shipments of TV panels are forecast to grow just 2.6 percent.

In 2019, three new 10.5-generation fabs – ChinaStar’s T6, BOE’s second fab and Foxconn/Sharp’s Guangzhou line – are expected to start mass production. All of them are assigned to manufacture TV panels, further boosting TV panel supply. “As the TV panel business is predicted to remain tough, panel makers, who enjoyed relatively better outcomes with monitor and notebook PC panels in 2018, will likely focus on the IT panel businesses,” Wu said.

The Large Area Display Market Tracker by IHS Markit provides information about the entire range of large display panels shipped worldwide and regionally, including monthly and quarterly revenues and shipments by display area, application, size and aspect ratio for each supplier.

Researchers from Chalmers University of Technology, Sweden, have discovered a simple new tweak that could double the efficiency of organic electronics. OLED-displays, plastic-based solar cells and bioelectronics are just some of the technologies that could benefit from their new discovery, which deals with “double-doped” polymers.

Double doping could improve the light-harvesting efficiency of flexible organic solar cells (left), the switching speed of electronic paper (center) and the power density of piezoelectric textiles (right). Disclaimer: The image may only be used with referral to Epishine, as supplier of the flexible solar cell. For instance: ‘The solar cell was supplied by Epishine AB.’ Credit: Johan Bodell/Chalmers University of Technology

The majority of our everyday electronics are based on inorganic semiconductors, such as silicon. Crucial to their function is a process called doping, which involves weaving impurities into the semiconductor to enhance its electrical conductivity. It is this that allows various components in solar cells and LED screens to work.

For organic – that is, carbon-based – semiconductors, this doping process is similarly of extreme importance. Since the discovery of electrically conducting plastics and polymers, a field for which a Nobel Prize was awarded in 2000, research and development of organic electronics has accelerated quickly. OLED-displays are one example which are already on the market, for example in the latest generation of smartphones. Other applications have not yet been fully realised, due in part to the fact that organic semiconductors have so far not been efficient enough.

Doping in organic semiconductors operates through what is known as a redox reaction. This means that a dopant molecule receives an electron from the semiconductor, increasing the electrical conductivity of the semiconductor. The more dopant molecules that the semiconductor can react with, the higher the conductivity – at least up to a certain limit, after which the conductivity decreases. Currently, the efficiency limit of doped organic semiconductors has been determined by the fact that the dopant molecules have only been able to exchange one electron each.

But now, in an article in the scientific journal Nature Materials, Professor Christian Müller and his group, together with colleagues from seven other universities demonstrate that it is possible to move two electrons to every dopant molecule.

“Through this ‘double doping’ process, the semiconductor can therefore become twice as effective,” says David Kiefer, PhD student in the group and first author of the article.

According to Christian Müller, this innovation is not built on some great technical achievement. Instead, it is simply a case of seeing what others have not seen.

“The whole research field has been totally focused on studying materials which only allow one redox reaction per molecule. We chose to look at a different type of polymer, with lower ionisation energy. We saw that this material allowed the transfer of two electrons to the dopant molecule. It is actually very simple,” says Christian Müller, Professor of Polymer Science at Chalmers University of Technology.

The discovery could allow further improvements to technologies which today are not competitive enough to make it to market. One problem is that polymers simply do not conduct current well enough, and so making the doping techniques more effective has long been a focus for achieving better polymer-based electronics. Now, this doubling of the conductivity of polymers, while using only the same amount of dopant material, over the same surface area as before, could represent the tipping point needed to allow several emerging technologies to be commercialised.

“With OLED displays, the development has come far enough that they are already on the market. But for other technologies to succeed and make it to market something extra is needed. With organic solar cells, for example, or electronic circuits built of organic material, we need the ability to dope certain components to the same extent as silicon-based electronics. Our approach is a step in the right direction,” says Christian Müller.

The discovery offers fundamental knowledge and could help thousands of researchers to achieve advances in flexible electronics, bioelectronics and thermoelectricity. Christian Müller’s research group themselves are researching several different applied areas, with polymer technology at the centre. Among other things, his group is looking into the development of electrically conducting textiles and organic solar cells.