sign in sign up
<<
Home , Layer (electronics), Organic electronics

Organic for a Better Tomorrow: Innovation, Accessibility, Sustainability

A White Paper from the Chemical Sciences and Society Summit (CS3)

San Francisco, California, United States

September 2012

Table of Contents

About the Chemical Sciences and Society Summit (CS3) ...... 2 Foreword: Letter from the 2012 CS3 Chairs ...... 3 Executive Summary ...... 4 Introduction ...... 7 Today …………………………………………………………………………………10 Organic Electronics: The Vision for Tomorrow ...... 14 Research Pathway to the Future ...... 20 Conclusion ...... 26 References ...... 27 2012 CS3 Participants ...... 31

Organic Electronics for a Better Tomorrow / 1

ABOUT THE CHEMICAL SCIENCES AND SOCIETY SUMMIT (CS3)

The annual Chemical Sciences and societal needs. This white paper presents Society Summit (CS3) brings together an international view on how the use of some of the best minds in chemical organic materials in electronic devices research from around the world and can contribute positively to creating a challenge them to propose innovative more innovative, accessible, and to society’s most pressing sustainable electronic world. needs in health, food, energy, and the The CS3 initiative is a environment. This unique gathering collaboration between the Chinese boasts an innovative format, aiming to Chemical Society (CCS), German set the course of international science, Chemical Society (GDCh), Chemical and rotates each year among Society of Japan (CSJ), Royal Society of participating nations. Chemistry (RSC), and American Organic Electronics for a Better Chemical Society (ACS). The annual Tomorrow: Innovation, Accessibility, symposia are supported by the National Sustainability summarizes the outcomes Natural Science Foundation of China of the fourth annual 2012 CS3, which (NSFC), German Research Foundation focused on organic electronics. Thirty (DFG), Japan Society for the Promotion top chemists and other scientists from of Science (JSPS), UK Engineering and China, Germany, Japan, the United Physical Sciences Research Council States, and the United Kingdom (EPSRC), and U.S. National Science assembled in San Francisco to identify Foundation (NSF). major scientific and technological This white paper was prepared research challenges that must be by science writer Leslie A. Pray, PhD, in addressed to advance the field of organic consultation with the American electronics in a way that best meets Chemical Society, and reviewed by 2012 CS3 participants.

Organic Electronics for a Better Tomorrow / 2

FOREWORD: LETTER FROM THE organic electronics and to offer research 2012 CS3 DELEGATION CHAIRS recommendations for advancing the field in a way that will maximize its potential We live in an electronic world. positive impact on society. Economic, health, and national security Our hope is that our research rely on and are positively impacted by recommendations will be recognized and electronic technology. However, the considered by science policy-makers resources and methodologies used to worldwide – not just in the field of manufacture electronic devices raise chemistry, but also in the broad range of urgent questions about the negative other scientific and engineering environmental impacts of the disciplines that impact organic manufacture, use, and disposal of electronics research and development. electronic devices. The use of organic While chemists play a vitally important materials to build electronic devices may role in synthesizing and transforming the offer a more eco-friendly -- and organic “building block” materials that affordable -- approach to growing our make organic electronics possible, our electronic world. Moreover, and some vision for the future will not be realized would say more importantly, organic without the cooperation of physicists and small , , and other other scientists and engineers from materials afford electronic structures across academia and industry. unique properties impossible to obtain with silicon alone, creating untold potential for novel functionality. However, the field of organic Xi Zhang electronics is in its infancy with respect Chair, China Delegation to devices on the market. Realizing the vision of organic electronics as a more Peter Bäuerle innovative, accessible, and sustainable Chair, Germany Delegation approach to growing our electronic world will require overcoming key Takuzo Aida research challenges. Chair, Japan Delegation Chemists, physicists, and other scientists and engineers engaged in Peter Skabara organic electronics research representing Chair, United Kingdom Delegation China, Germany, Japan, the United Kingdom and the United States gathered Cherie Kagan in San Francisco in September of 2012 Chair, United States Delegation to discuss their visions for the future of

Organic Electronics for a Better Tomorrow / 3

EXECUTIVE SUMMARY

Chemists, physicists, and other scientists Potential applications of organic and engineers are synthesizing and electronics span a broad range of fields, manipulating a wealth of new organic including medicine and biomedical materials in ways that will change the research, environmental health, way society interacts with technology. information and communications, and These new materials create novel national security. properties impossible to replicate with Because of the lower cost and silicon, expanding the world of higher throughput manufacture of electronics in ways unimaginable until organic-based electronic devices, now. Organic Electronics for a Better compared to today’s silicon-based Tomorrow: Innovation, Accessibility, devices, organic electronics also promise Sustainability examines where organic to expand the use of electronic electronics are today, where chemical technology in resource-limited areas of scientists envision the field is heading, the world where supplies are limited or and the scientific and engineering the necessary infrastructure is lacking. challenges that must be met in order to Already, organic solar cells are being realize that vision. installed on rooftops in African villages Already, consumers are using that lack access to standard on-grid organic electronic devices, such as smart , providing rural populations phones built with organic light emitting with a safer and cheaper alternative to (OLED) displays, often without kerosene. even being aware of the organic nature Not only do organic materials of the electronic technology in hand. The promise more innovative and accessible Samsung Galaxy line of OLED-based electronic technologies, they also smartphones occupies a major share of promise more sustainable electronic the global smartphone market. technologies. The potential for greater Potential future applications are sustainability extends across the entire enormous and untold. Organic materials life cycle of electronics, beginning with are being studied and developed for their the use of materials that are synthesized, potential to build devices with a rather than mined from the earth, and flexibility, stretchability and softness ending with potentially biodegradable or (“soft electronics”) not afforded by recyclable devices. It is not just the silicon or any other inorganic materials – devices themselves that promise to be that is, electronic devices that bend, more eco-friendly than silicon-based twist, and conform to any surface. electronics, but also their manufacture. Imagine a smartphone that folds like a Today, the major focus of map. Devices made with organic research and development in organic materials also have the potential to electronic is on three main types of interface with biological systems in existing applications: displays and ways not possible with inorganic lighting, , and solar cells. The materials. Imagine an artificial skin with vision for the future is to move beyond a tactile sensitivity approximating real these already existing applications and skin that can be used to treat burns or explore new realms of electronic use. add functionality to prosthetic limbs. The intention is not that organic

Organic Electronics for a Better Tomorrow / 3

electronics, or any specific type of the formation of many materials being a organic electronics, will replace silicon- major problem. Until wide-scale based electronics. Indeed, organic industry-level production is achieved, molecules and materials are often used future visions for organic electronics in combination with silicon materials. will remain just that – visions. Rather, the vision for the future is one of CS3 participants identified four an expanded electronic landscape – one major scientific and technology research filled with new materials that make challenges that must be addressed in electronics more functional, accessible, order to achieve high yield and and sustainable. uniformity. The 2012 CS3 participants articulated three visions for the future of 1. Improve controlled self- organic electronics: assembly. Chemists need to gain better control over the self- 1. Organic electronic devices will assembly of organic electronic do things that silicon-based molecules into ordered patterns electronics cannot do, to ensure that the structures being expanding the functionality and assembled are reproducible. accessibility of electronics. Improved controlled self- 2. Organic electronic devices will assembly requires a better be more energy-efficient and understanding of the electronic otherwise “eco-friendly” than properties of organic materials, today’s electronics, contributing especially when those materials to a more sustainable electronic are in contact with other world. materials (i.e., their interfacial 3. Organic electronic devices will behavior). Only with that be manufactured using more knowledge will researchers be resource-friendly and energy- able to predict how organic efficient processes than today’s electronic materials actually methods, further contributing to perform when integrated into a more sustainable electronic devices, and only with those world. predictions will engineers be able to develop industry-scale Arguably the greatest overarching synthetic processes. challenge to realizing these visions is creating electronic structures at industry- 2. Develop better analytical tools. level scale with high yield and Better analytical tools are needed uniformity. This is true regardless of to detect and measure what is type of material or application. While happening with respect to the electronics industry has already structure and chemical achieved enormous success with some composition when organic organic electronic structures, such as materials are assembled and those being used to build OLED-based integrated into electronic smartphones, most organic electronic structures and devices, ideally at structures are being synthesized on only every step along the way. These very small scales, with reproducibility in

Organic Electronics for a Better Tomorrow / 5

tools need to be non-destructive, non-invasive, and high-speed. While chemical scientists have been critical drivers of organic electronics and 3. Improve three-dimensional (3D) will continue to serve an essential role in processing technology. Many expanding the landscape of organic organic electronic structures can electronics, other areas of scientific and be assembled on flexible engineering research are equally substrates using existing printing essential. Chemists, physicists, material technologies. However, scientists and other scientists and fabrication of 3D organic engineers must combine their expertise electronic structures with the and work together to realize the full same precision achievable with potential of organic electronics. two dimensional (2D) printing Multidisciplinary research and training technology remains a major programs that bring together scientists challenge to reliable high- and engineers from different fields of throughput manufacturing of knowledge, as well as from different organic electronic devices. sectors of activity (i.e., academia, industry, government), will facilitate the 4. Increase multi-functionality of collaborative effort needed to meet these organic electronic devices. As scientific and technological challenges chemists gain better control over the synthesis of organic materials, they and their engineering collaborators will be able to build increasingly sophisticated optoelectronic1 and other devices with multiple functions. However, in order to fully realize the multifunctional capacity of organic chemistry, chemists need to broaden their research focus beyond “charge- carrier” transport (i.e., and holes, respectively) and gain a better understanding of optical, magnetic, thermal and other properties.

1 An optoelectronic device is an electronic device that produces or interacts with light. Organic optoelectronic devices already in the marketplace include organic light- emitting () and organic solar cells.

Organic Electronics for a Better Tomorrow / 6

INTRODUCTION

We live in an increasingly electronic replicate with silicon. These materials world, with occupying a hold tremendous promise to expand our central part of our lives. In 2012, there electronic landscape in ways that will were an estimated 30-40 processors per radically change the way society person, on average, with some interacts with technology. Organic individuals surrounded by as many as Electronics for a Better Tomorrow: 1000 processors on a daily basis. While Innovation, Accessibility, Sustainability silicon electronics has solved many of examines where organic electronics are the challenges associated with our today, where chemical scientists increased use of electronics, there are envision the field is heading, and the limits to what silicon can do. Chemists scientific and engineering challenges are synthesizing a wealth of new organic that must be met in order to realize that materials for use in electronic devices vision. that create novel properties impossible to

Figure 1. From silicon to carbon. Silicon (S) and carbon (C) may be in the same family on the periodic table, but the properties they confer on electronic structures are anything but similar. Source: Jin Zhang.

Organic Electronics for a Better Tomorrow / 7

Our Electronic World

While Moore’s prediction that the number of transistors per chip would double every 18 months has more or less borne true, many scientists and engineers speculate that such growth is not indefinite and that a limit will be reached. While the miniaturization of silicon-based electronic structures has created an electronic world full of affordable, high- performing devices, still there are things that silicon-based electronics cannot do and will never be able to do. Organic materials, whether used in combination with silicon or not, hold the potential to expand our electronic world in ways unimaginable when Moore made his prediction some forty years ago.

Organic Materials for Electronics: A electronic materials in Primer particular are one of the most active areas of organic electronic research, so Chemical scientists work with several much so that polymer-based organic different types of organic materials in electronic devices (and device their research on electronics. These prototypes) have significantly improved materials include small molecules2 and in performance over the past decade. For polymers; fullerenes, nanotubes, example, power conversion efficiencies graphene, and other carbon-based (PCEs) of organic (OPVs) molecular structures; ensembles of have increased from 5 percent in 2005 to molecules and molecular structures; and > 10 percent in 2012. This increased hybrid materials. They use these performance is being driven by newly materials to build electronic structures developed polymers with improved solar and then integrate those structures into light absorption properties and superior electronic devices. Many of these mobilities. For organic devices are early-stage prototypes, with devices, charge-carrier mobilities3 have major scientific and engineering increased from less than 0.01 centimeter challenges still to be surmounted before squared per Volt-second (cm2/Vs) in the prototypes can become real-world 2000 to greater than 1.0-3.0 cm2/Vs in products. But others are already 2010. Some high-performance polymers commercial realities, some being used exhibit as great as 5.0-10.0 cm2/Vs on a widespread basis. For example, mobility. Increasing charge-carrier both small molecules and polymers are mobility and thereby improving device being used in the manufacture of OLED performance even further poses one of displays (e.g., TV and cell phone the greatest challenges to the field of displays), solar cells, and transistors. polymer electronics. An additional concern is that most reported charge-

2 “Small ” is used in this White Paper in reference to organic molecules 3 “Charge-carrier” mobilities that are smaller than polymers, that is, characterize how quickly charged both monomers and oligomers. particles move through a .

Organic Electronics for a Better Tomorrow / 8

carrier mobility values are for isolated and other flexible devices. But they are and optimized systems and that mobility also being investigated for their charge decreases when such systems are storage potential, conducting ink integrated into actual devices. capacity (e.g., graphene-based inks are Carbon-based materials hold being investigated for their use in tremendous promise for the field of security packaging such that tampering organic electronics because carbon breaks the printed circuit, sounding an comes in so many different forms, with a alarm), and other applications. Multi- wealth of chemistries associated with walled carbon nanotubes are being those different forms. Fullerenes were produced on a large scale (e.g., the first carbon nanostructures produced, Hyosung, Inc., South Korea, produces in 1990. Carbon nanotubes were more than one ton daily) and being used produced shortly thereafter and then, in as electrically conductive parts in 2004, graphene was isolated. Carbon- ATM machines and other devices. But based materials are being researched and single-walled developed mostly to create bendable, or production has yet to be scaled up to an rollable, electronic displays, solar cells, industrial level.

Figure 2. Improved electronic performance in devices made with organic polymer materials, 2000-present. Top: Continued research on polymer materials has led to a steady increase in charge-carrier mobilities in organic field effect transistors (OFETs) (top) and increased photoconversion efficiencies (PCEs) for organic solar cells (bottom). Source: Lixiang Wang.

Organic Electronics for a Better Tomorrow / 9

Single Molecule Organic Electronics: Illusion or Insight?

The field of single molecule organic electronics has made great strides since the world’s first single-molecule organic electric device, the molecular rectifier, was envisioned in the mid-1970s. Researchers have learned how to alter structures of single molecules in ways that change conductance and other electronic properties. However, they still face daunting challenges to integrating those structures into macroscopic circuitries and into actual usable devices. The field is still occupied largely by academic researchers, with some scientists speculating that the notion of single-molecule electronics is but an illusion. Or at least the notion of a single-molecule is but an illusion. There are other potential applications. Because single molecule devices involve constricting all electrical current to flow through a single molecule such that anything perturbing the molecule is sensed by the device, single molecule devices could make for fantastically sensitive sensors. At the very least, while no single molecule electronic device has yet become a commercial reality, research in the field has yielded a wealth of new knowledge about the chemistry of organic electronics. By shrinking electronic systems down to a single molecule, chemical scientists are learning about charge movement through molecules, molecule-electrode interfacial activity, and other phenomena that help to understand how organic molecules function as electronic device components.

ORGANIC ELECTRONICS TODAY

Organic electronics is not a new field. and therefore they Electronic devices made with organic do not require backlights. They require materials already have multiple less power and are more energy-efficient applications and have been widely than backlight-dependent display commercialized, mostly in display (e.g., technology. smart phone displays), photovoltaic, and OLEDs are already widely transistor technologies. commercialized in many Samsung and other smartphone models. The Samsung Organic Display Technology Galaxy line of OLED-based smartphones occupies a significant Organic light-emitting diodes (OLEDs) portion of the global smartphone market. are built from one or more layers of Additionally, Samsung and LG organic and hybrid material (either small Electronics have both announced molecules or polymers) sandwiched forthcoming launches of large-screen between two electrodes (e.g., indium tin OLED TVs. The new TVs are expected oxide), all on a plastic or other substrate. to not only be more spectacular than Unlike other display technologies, which today’s TV technology, with respect to require a backlight in order for the crisper and sharper contrasts, but display to show, OLEDs generate their also lighter, thinner, and more energy- own light via efficient.

Organic Electronics for a Better Tomorrow / 10

Figure 3. Building better OLED displays. Left: Samsung has announced the near-future release of a foldable smartphone built with a flexible plastic OLED display; the phone can be folded to an eighth of its size. Source: Josh Miller/CNET. Right: Both Samsung and LG Electronics have announced near-future releases of 55-inch, 4-mm thick OLED display TVs. Source: LG Electronics.

Organic Photovoltaics (OPVs) occur at these various interfaces, engineers will be able to build interfacial Organic photovoltaics (OPVs), or structures that drive energy conversion organic solar cells, are generally viewed even more efficiently than today’s as one of most exciting near-future devices do. While current OPV applications of organic electronics, not technology boasts conversion necessarily as a replacement for silicon- efficiencies that exceed 10 percent, based PVs, rather because of unique reaching even 12 percent, some ways that OPVs can be used due to their researchers predict organic solar cells flexibility, large-area coverage, and low will reach 15-20 percent efficiency. cost. However, a key challenge to expanding production is Transistor Technology industry-scale reproducibility. The harvesting of solar energy Transistors are considered a fundamental relies on chemical and physical “building block” of modern electronic interactions at the interfaces between devices, either amplifying signals or materials that harvest the light and operating as on-off switches. There are materials that transport electrical current. many different types of transistors. Most These interfaces can be either organic- organic transistors are organic field- organic or organic-inorganic. As effect transistors (OFETs). OFETs have chemical scientists gain a better several unique properties not shared by understanding of the processes that silicon transistors, most notably their

Organic Electronics for a Better Tomorrow / 11

flexibility. Because OFETs can be using simple and relatively inexpensive manufactured at or near room techniques, such as processing. temperature, they enable the By 2020, with the synthesis of even manufacture of integrated circuits on more advanced materials, mobilities plastic or other flexible substrates that could increase to as much as 100 would otherwise not withstand the high- cm2/Vs. As with small-molecule OFETs, temperature conditions of silicon-based polymer OFETs have also increased in device manufacture. OFETs are also performance, with typical mobilities highly sensitive to specific biological increasing from about 0.01 cm2/Vs in and chemical agents, making them 2000 to greater than 1.0-3.0 cm2/Vs in excellent candidates for biomedical 2010. sensors and other devices that interface Despite this progress, several with biological systems. challenges remain before OFETs will With the synthesis of new become a widespread commercial organic materials, chemists have reality. For example, only recently have improved charge-carrier mobilities for scientists demonstrated the fabrication of small-molecule OFETs from < 1 cm2/Vs thermally stable flexible OFETs. High in 2000 to 8-11 cm2/Vs today. Initially, thermal stability is prerequisite to the improved mobilities were obtained integrating OFETs into biomedical only under very clean conditions in devices; otherwise they won’t survive ultrahigh vacuum chambers. However, high-heat sterilization. recent results suggest that high- performance OFETS can be fabricated

From Chemist to Consumer: OLED Displays

The touch-screen display on the Galaxy S series of smartphones manufactured by Samsung Electronics is testament to the tremendous progress already achieved in the field of organic electronics. Most other smartphones, as well as computers, tablets, high definition sets and other similar devices, use liquid crystal display (LCD) technology, an organic-inorganic hybrid electronic technology that requires a backlight to produce the image displayed on the screen. But the Galaxy S uses a technology that doesn’t require a backlight: organic light-emitting diode (OLED) display technology. OLEDs emit their own colored light to produce images. Because they do not need backlights, OLED displays are thinner and lighter than LCD displays. They have other potential advantages as well, including flexibility, with efforts underway to develop and commercialize foldable OLED display smartphones and other devices. Other similar devices are emerging in the marketplace. For example, the PlayStation (PS) Vita, a handheld game console, boasts a 5-inch touchscreen OLED display. These and other future OLED devices exemplify how fundamental research in organic chemistry, including the of new organic materials and the characterization of those materials, can evolve into mass production of a novel technology. To advance the technology even further, chemists, physicists, and other scientists are collaborating to develop yet more advanced organic materials with even better electronic and other properties. Researchers predict that OLED lighting technology, including large-area (white) lighting, will become a commercial reality within the next five years.

Organic Electronics for a Better Tomorrow / 12

Organic Chemists Outsmart Counterfeiters

Organic thin-film transistors (OTFTs) create a wealth of innovative opportunities for electronic applications. For example, scientists are fabricating OTFTs on banknote surfaces as an anti-counterfeiting feature. Not only are OTFTs thinner than even the thinnest silicon-based transistors (less than 250 nanometers [nm], compared to 20 micrometers [µm]), making it possible to embed them into the banknote paper, they also operate at a low enough voltage (about 3 volts [V]) that they do not cause any damage to the paper. Most importantly, because they are made with organic materials, the OTFTs are flexible enough that they can withstand repeated crumpling, creasing, and sharp folding. OTFTs on banknotes exemplify how research on organic materials, in this case with German and Japanese chemists collaborating on the use of very thin polymer substrates as the starting material for fabrication of the OTFTs, can eventually lead to development of a novel device otherwise impossible to build with silicon-based electronic structures. Flexible organic thin-film transistors are also being studied and developed for their potential applications in a wide range of other types of bendable devices, such as rollable solar cells.

Figure 4. OTFTs make for good anti-counterfeiting features in banknotes. Left: Polymer substrate with functional OTFTs wrapped around a cylinder with a radius of 300 µm. Source: Sekitani et al. 2010. Right: Banknote with OTFTs embedded as a counterfeiting feature. Source: Zschieschang et al. 2011.

Organic Electronics for a Better Tomorrow / 13

ORGANIC ELECTRONICS: THE electronics cannot do, expanding the VISION FOR TOMORROW functionality and accessibility of electronics. As chemists continue to synthesize and functionalize new and improved organic Organic materials give electronic materials for use in electronic structures devices unique properties impossible to and devices, the field of organic achieve with silicon-based electronic electronics will likely expand in ways structures, enabling a broad range of not even imaginable today. Some innovative “out-of-the-box” applications have already been realized, applications. These properties include like the OLED smartphones and the low- sensing, biocompatibility, and flexibility. cost solar cells being installed on Because of the unique structural rooftops in rural off-grid communities in and functional variation of organic South Sudan. Some, like the ultra-thin materials, arguably one of the greatest OLED TVs and foldable smartphones, areas for innovation in the field of are expected to be launched in the near organic electronics is in sensing -- that future. Others, like electronic skin that is, the use of electronic devices to sense mimics human skin with its tactile chemical or biological substances in the sensitivity, will take longer. Still others environment, in or on the human body, cannot be foreseen. The potential future in food and water, or elsewhere. For applications are many and varied, example, chemical scientists envision spanning across multiple fields: diagnostic sensors that detect changes in medicine and biomedical research, biomarker levels (e.g., changes in energy and the environment, national glucose levels in people with diabetes); security, communications and environmental sensors that detect toxins entertainment, home and office in food or water; and national security furnishings, clothing and personal sensors that detect trinitrotoluene (TNT) accessories, and more. or other explosives. Biosensors are Not only will the field of organic among the most exciting near-future electronics yield innovative applications applications of organic electronics. As not even imaginable today, it also has just one example, chemical scientists the potential to make electronics envision biosensors that not only detect production, use, and disposal more glucose levels in people with diabetes, environmentally sustainable. Chemists but also actually dispense the and their colleagues are seeking ways to appropriate dose of insulin at the right make organic electronics – both the time. devices themselves and the manufacture Not only are organic electronic of those devices – more resource- structures more chemically compatible conservative and energy-efficient than with biological systems than silicon- today’s silicon-based electronic world. based devices are, they also enable a CS3 participants identified three flexibility, stretchability and mechanical overarching visions for the future of “softness” not possible with silicon. organic electronic materials: Together, these properties create the potential for innovative bio-electronic Vision #1: Organic electronic devices sensors that can conform to the curvature will do things that silicon-based and moving parts of the human body.

Organic Electronics for a Better Tomorrow / 14

Flexible organic thin-film transistors makes them mechanically compliant not (OTFTs) are being used to develop just with biological systems, but also electronic skins with tactile sensitivity with a wide range of other types of and other sensing capabilities. The hope curved surfaces and movable parts. is that this technology will be used to Scientists envision flexible displays, build artificial skin for burn patients, solar cells, sensors, and batteries with prosthetics with tactile capabilities, and applications in automobiles, clothes and other touch-sensitive devices impossible other fabrics, and machinery. As just one to build with silicon-based electronic example, the Smart Forvision Concept structures. In the very distant future, Car has been proposed as a futuristic car some scientists wonder whether such that would boast, among many other “robotic skin” might even be capable of weight and energy-saving features, a detecting emotional states. transparent roof for The flexible (“soft”) nature of fueling the car’s climate control system carbon-based and other organic materials and OLED lighting.

Figure 5. Flexible organic . Circuits fabricated on a flexible and transparent organic substrate. Flexibility is an important advantage of organic materials. Source: Sun et al. 2011.

Organic Electronics for a Better Tomorrow / 15

Figure 6. Using organic materials to create artificial skin. Scientists are using organic field-effect transistor (OFET) architecture to build electronic material that mimics human skin. The electronic skin is a stretchable two-dimensional (2D) array of tactile sensors that collect environmental signals and translate those signals into information. Source: Sokolov et al. 2012.

Vision #2: Organic electronic devices Northern Europe where long spells of will be more energy-efficient and sunlight are but a dream. otherwise “eco-friendly” than today’s As with organic solar cells, electronics, contributing to a more chemical scientists and engineers hope sustainable electronic world. to improve the energy efficiency of organic transistors as well, in the case of As chemical scientists and engineers OFETs by lowering their operating continue to improve the synthesis and voltages. Lowering OFET operating characterization of organic materials for voltages is more than an energy use in electronics, their hope is that the efficiency goal. It will also allow use of such materials will lead to more chemists to take advantage of the energy-efficient electronic displays and biocompatibility of OFETs; high-voltage lights, solar cells, transistors, and other FETs generate fatal levels of heat. electronic devices. For example, while In addition to increasing energy organic solar cells are already very efficiency, as chemists continue to study energy efficient, with an energy and improve their understanding of the “payback” time of less than six months, electronic behavior of organic materials, their energy efficiency needs to continue engineers will be able to build devices to improve in order to succeed as a that last longer and that are recyclable or widespread technology in places like perhaps even biodegradable.

Organic Electronics for a Better Tomorrow / 16

Off-the-Grid Organic Electronics: Making Electronics More Accessible

While we live in an increasingly electronic world, access to that world is limited. An estimated 1.3 billion people have no access to electricity, with many people relying on kerosene, batteries, or diesel-fueled generators. Because of their cheaper manufacturing costs, organic electronics promise not only to change the way people use technology, but also to expand the use of technology to populations without access to on-grid electricity. For example, in 2011, Eight19, a Cambridge, UK-based company dedicated to the development and manufacture of organic solar cells, launched a program called Indigo to provide off-the-grid solar-powered energy to rural markets. The pay-as-you-go program eliminates the high initial purchase cost of solar power systems (customers pay for the system with scratch cards on a week-by-week basis until they own the product outright), costs less than kerosene (after the customer has paid for the product, usage is free), and is environmentally safer than kerosene (kerosene emits poisonous fumes). The technology being used in the Indigo program -- indeed all organic solar cell technologies -- would not be possible without ongoing work by organic chemists to synthesize and functionalize new materials.

Vision #3: Organic electronic devices which involves removing materials and will be manufactured using more disposing of those excess materials. In resource-friendly and energy-efficient addition to using fewer materials, processes than today’s methods, further chemists are seeking ways to use safer contributing to a more sustainable materials. For example, many polymers electronic world. require carcinogenic , including some solvents not even allowed in the The use of organic materials to build EU printing industry because of their electronic devices holds the promise that toxicity. Chemists are hoping to design future electronic manufacturing methods polymers that are soluble in non-toxic will rely on fewer, safer, and more solvents and that rely on more benign abundant raw materials. The vision is for methodologies in general. Finally, the resource-efficient synthetic resource-friendly vision is for reliance methodologies, whereby both the on more abundant starting materials, devices themselves and the thereby conserving precious and manufacturing of those devices use less endangered resources. For example, material than today’s silicon-based graphene is being investigated as a electronic methodologies require. For replacement for (ITO), example, materials can be saved by as indium is considered a limited relying on less wasteful processes, such resource. as printing, whereby materials are added In addition to becoming more to structures or devices by layer as resource-friendly, organic electronic they are built, in contrast to spin- manufacturing methods will also become

Organic Electronics for a Better Tomorrow / 17

more energy-efficient as materials and intensive, with the scale of production process engineers continue to learn and being too small to invest in the improve methodologies for synthesizing infrastructure necessary for recovering organic materials and assembling lost heat. As the manufacture of carbon- electronic structures. The vision is for based electronics expands in scale and manufacturing processes with fewer the volume of material being processed steps and with methods for recovering increases, the hope is that process and lost heat. Currently, both carbon materials engineers will develop ways to nanotube and graphene synthesis build the infrastructure needed to methodologies are highly energy- reclaim heat.

Figure 7. Accessible electronics. Pay-as-you-go organic solar cell technology is being distributed throughout rural areas of southern Africa and elsewhere, providing a low-cost and safe alternative to kerosene. Source: Eight19.

Organic Electronics for a Better Tomorrow / 18

Sustainable Electronics

What is “sustainable electronics”? And how can organic electronics help to make electronics more sustainable? The meaning of sustainability is open to interpretation. The 2012 CS3 participants considered several different definitions of sustainable electronics. Environmental sustainability. For most people, mention of “sustainable electronics” brings to mind images and concerns about energy efficiency, resource use, and waste disposal or recycling – that is, building an electronic world that enables sustainable management of natural resources. For example, how can electronic devices be built that operate more energy efficiently than today’s silicon-based devices? Creating more sustainable electronic products is not just about building a more “eco-friendly” solar cell or other device, but also using more “eco-friendly” manufacturing methods to do so. In fact, sustainability cuts across the entire life cycle of an electronic product, from raw resources to disposal. Chemists and other scientists and engineers are using organic materials to steer electronics into the future in a more environmentally sustainable way than is possible in today’s electronic world, for example by using carbon-based materials instead of precious earth-mined resources and by relying on safer and less energy- intensive manufacturing methods than silicon-based electronic processing methods. Social sustainability. More broadly, “sustainable electronics” also implies building an electronic world that enables a more sustainable society – that is, as described in the United Nations 2012 report Realizing the Future We Want for All, one that ensures “inter-generational justice and a future world fit for children … in which children will be able to grow up healthy, well-nourished, resilient, well-educated, culturally sensitive and protected from violence and neglect …” Organic electronics is helping to steer electronics into the future in a way that ensures such justice and in a way not possible with today’s silicon-based electronics. Specifically, organic electronics is making electronics in general more accessible to people worldwide. Chemists are using organic materials to develop “off-the-grid” solar cells, low-cost water sensors, and other devices for use in areas where people otherwise do not have the resources or infrastructure to light their homes or monitor water quality. Even in resource-rich areas where electronics are already pervasive, organic materials hold the potential to expand the use of electronic products in ways that will benefit society. One of the potential advantages of organic electronics is its more cost-effective large-scale manufacture, compared to silicon electronics, which creates opportunities for high-throughput production of item-level sensors and other devices that could be used to monitor and protect our environment, including our food supply, in ways not possible until now. For example, chemists envision item-level food spoilage sensors that would significantly reduce the amount of wasted food. Technology sustainability. Finally, “sustainable electronics” implies that electronics itself is long lasting – not just the actual devices, but also organic electronic technology in general. Chemical, materials, and other scientists and engineers have only just begun to tap the vast potential for innovative functionality made possible through the use of organic materials in electronic devices. The way that organic electronic structures interact with biological systems opens up a vast world of possibility with respect to medical, sensing, and other human interface applications. The versatile nature of organic electronics, combined with the promise the field holds forth for environmental and social sustainability, point the way to a very long-lived set of technologies.

Organic Electronics for a Better Tomorrow / 19

RESEARCH PATHWAY TO THE be able to predict how organic FUTURE electronic materials actually perform when integrated into Realizing the visions articulated in the devices, and only with those previous section will require overcoming predictions will engineers be able several major scientific and engineering to develop industry-scale research challenges. Arguably the synthetic processes. greatest overarching challenge to the field of organic electronics is to create (2) Develop better analytical electronic structures at industry-level tools. Better analytical tools are scale with high yield and purity. This is needed to detect and measure true regardless of the type of material what is happening with respect to used or application. Until industry-level structure and chemical production of well-controlled structures composition when organic is achieved, the visions for organic materials are assembled and electronics will remain just that – integrated into electronic visions. Only by addressing these structures and devices, ideally at challenges will the field of organic every step along the way. These electronics expand the functionality, tools need to be non-destructive, accessibility and sustainability of our non-invasive, and high-speed. electronic world: Additionally, highly sensitive analytical methods are necessary (1) Improve controlled self- to detect degradation products of assembly. Chemists need to gain organic materials under operating better control over the self- conditions in order to better assembly of organic electronic understand the break-down molecules into ordered patterns mechanism of such materials and to ensure that the structures being eventually increase their lifetime assembled are reproducible. in electronic devices. Today, a lack of reproducibility in the formation of many (3) Improve three-dimensional materials precludes industry- (3D) processing technology. scale processing. To overcome Many organic electronic this, chemists need to gain better structures can be assembled on control of the self-assembly of flexible substrates using existing organic electronic molecules into printing technologies. However, ordered patterns. Improved fabrication of 3D organic controlled self-assembly requires electronic structures with the a better understanding of the same precision achievable with electronic properties of organic two dimensional (2D) printing materials, especially when those technology remains a major materials are in contact with challenge to reliable high- other materials (i.e., their throughput manufacturing of interfacial behavior). Only with organic electronic devices. that knowledge will researchers

Organic Electronics for a Better Tomorrow / 20

(4) Increase multi-functionality fully realize the multifunctional of organic electronic devices. As capacity of organic chemistry, chemists gain better control over chemists need to broaden their the synthesis of organic research focus beyond “charge- materials, they and their carrier” transport (i.e., electrons engineering collaborators will be and holes, respectively) and gain able to build increasingly a better understanding of optical, sophisticated optoelectronic and magnetic, thermal and other other devices with multiple properties. functions. However, in order to

Organic Electronics: The Role of Chemistry

Chemistry research plays a critical role in the development and commercialization of organic electronics. After all, it is chemists who synthesize and functionalize the organic materials being used in the OLED smartphones, organic solar cells, and other devices either already on the market or in the development pipeline. Without those materials, these devices would not exist. Not only do chemists provide the raw starting materials, but they also play a key role in improving the performance of those materials over time. For example, charge-carrier mobilities of polymer-based OFETs have increased dramatically over past 10 years, from 0.01 cm2/Vs in 2000 to greater than 1.0-3.0 cm2/Vs in 2010, largely because scientists know a great deal more about the chemistry of the polymers than they did in the past. Still, there is a great deal more to learn. Many high-performance polymers being developed for use in organic electronics show non-textbook behavior, making it difficult to predict and control how polymeric structures will actually pack and perform once integrated into electronic systems. The reasoning behind this chemical behavior, and the possible uses of these polymers are still unknown. Continued research will help chemists to gain a better understanding of how these materials behave when they are integrated into electronic systems and hopefully point the way to even better- performing polymer-based OFETs.

Organic Electronics for a Better Tomorrow / 21

industrial scale-up of polymer-based Research Challenge #1: Improve electronics will require a more robust Controlled Self-Assembly understanding of polymer self-assembly. For all organic materials, Organic chemistry enables a vast array chemists need to be able to model of complex structures and large-scale structure-property relationships at the molecular assemblies to be built. molecular level so that they can design However, the actual self-assembly4 systems with more controlled self- process is complex and still very poorly assembly, regardless of whether that understood. Some design rules are self-assembly occurs in solution (i.e., in beginning to emerge for small molecule ink) or on a surface. In other words, they self-assembly, but for the most part must develop a more predictive science chemists are still operating on a largely of organic electronics. Otherwise, trial-and-error basis. While it is known synthesis will continue to yield that small changes in microstructure can decidedly non-uniform mixtures of significantly impact self-assembly in the structures that behave in unpredictable solid state, in most cases it is difficult or ways. impossible to predict how. Without The issue of batch variation and controlled self-assembly of organic reproducibility, or lack thereof, raises electronic structures, the manufacture of questions about whether some defects or devices built from those structures will impurities might be tolerable. It appears be hindered and visions for the future of that most are not, with defects occurring organic electronics thwarted. at frequencies of less than one percent For polymer materials in having significant impact on particular, improved control of performance, especially for small morphology is arguably among the molecule aggregate electronic devices. greatest challenges to moving the field Whether defect-tolerant molecular forward. This is true even for P3HT architectures exist and, if so, under what [poly(3-hexylthiophene-2,5-diyl)], the conditions, remain a matter of well-studied of polymeric electronic investigation. materials, especially for OPVs. Even The challenge of reproducibility though the mechanism of P3HT is especially acute for large-scale polymerization is well understood, synthesis of carbon-based materials. recent research has demonstrated how Currently, only gram quantities of semi- certain defects that significantly impact conducting carbon nanostructures can be electronic performance emerge even manufactured. Even then, defects are with the most commonly used synthetic pervasive, with typical batches being protocol. Even for commercial polymer heterogeneous mixtures of forms with materials already available for purchase, varying electronic and other properties. batch variation is significant. Thus, A better understanding of self-assembly, including a better understanding of kinetic versus thermodynamic control 4 In this White Paper, self-assembly is during the self-assembly process, would defined as the spontaneous ordering of help chemical engineers to develop the patterned building blocks at a necessary selective synthesis tools for macroscopic scale. separating semi-conducting carbon

Organic Electronics for a Better Tomorrow / 22

nanostructures from other types of The need for a greater molecular structures. understanding of interfacial behavior, especially interfacial self-assembly, is The Importance of Understanding true of all organic-organic interfaces Interfacial Behavior (e.g., assemblages of multiple layers of organic materials, single molecules in Improved self-assembly requires not contact with a carbon nanotube) and all only a greater understanding of the organic-inorganic interfaces (e.g., single electronic properties of any given organic molecules in contact with an organic material, but also how those electrode). While molecule-electrode properties manifest when the material is interfaces are key to increasing the in contact with another material. energy efficiencies of many devices, any Chemical scientists need to gain a better or all of these different points of contact understanding of interfacial chemistry can impact electronic behavior. and the impact of the interface on device The significance of the interface performance. For example, graphene is not limited to the electronic structures materials have charge-carrier mobilities or devices themselves. Interfacial on the order of 200,000 cm2/Vs in a behavior also impacts manufacturing. vacuum environment. But those Chemists need to gain a better mobilities drop orders of magnitude understanding of the various molecule- when the same materials are assembled interactions that occur during on substrates. The mechanism and solution processing (e.g., inkjet or screen interfacial chemistry responsible for printing). driving this drop in mobility is still unknown.

Organic Electronics for a Better Tomorrow / 23

Figure 8. The complexity of self-assembly calls for a complexity science approach: The self-assembly of well-ordered patterns of organic electronic materials, whether those materials are molecules, polymers, carbon-based or not, is very difficult to predict and control. Until such self-assembly is better understood, such that well-controlled structures can be synthesized repeatedly and reliably, large-scale production of many of the envisioned applications for organic electronics will not be possible. Chemists need to gain a better understanding of self-assembly in order to achieve the prediction and control needed for industry-level production. Some chemists are calling for a systems-level approach to studying the complexity of self-assembly. Source: Würthner and Meerholz 2010.

Research Challenge #2: Develop Better molecular environments of the structures Analytical Tools they are building. Better tools are needed for analyzing the molecular composition, Reliable analytical tools are key to molecular organization, and local building a predictive science of organic electronic and other properties of the electronics. Only when scientists are organic electronic systems they are able to better characterize the electronic building. and other properties of their systems at A stronger fundamental the highest possible resolution will they measurement science would not only be able to predict how molecular help with developing a more predictive structure impacts performance. science of organic electronics, it is also Currently, chemists have limited key to scaling organic electronic capabilities to characterize the local processing up to an industry level. In

Organic Electronics for a Better Tomorrow / 24

order to guarantee quality control, process engineers need to know what is Research Challenge #4: Increase happening at every point in the process. Multi-Functionality of Organic They need non-invasive, non- Electronic Devices destructive, high-speed analytical tools. Organic electronic devices can do more Research Challenge #3: Improve than transport electronic information. Three-Dimensional (3D) Processing They can also transport optical, Technology magnetic, and thermal information. Indeed, many of the organic electronic In order to scale organic electronic devices already on the market are multi- processing up to an industry-level functional. For example, organic light- standard, chemical scientists and emitting diodes (OLEDs) and organic engineers need improved three- solar cells are multi-functional dimensional (3D) fabrication optoelectronic devices, that is, electronic technologies. An important advantage of devices that use or produce light in many organic electronic structures and addition to using or producing electrons. devices is that they can be assembled on As chemists gain better control over the plastic, paper and other flexible synthesis of organic materials, they and substrates using existing low-cost, high- their engineering collaborators will be throughput inkjet printing technologies. able to build increasingly sophisticated Printing also enables large-area optoelectronic and other multi-tasking fabrication of OLEDs, organic solar devices with multiple inputs and cells, OFETs and other organic multiple outputs. For example, electronic devices. Moreover, its researchers envision multi-tasking additive approach makes for more window glazings that function as solar sustainable production (i.e., necessary cells that generate electricity and as resources are added as needed rather OLEDs that generate light. In order to than excess resources being subtracted fully realize the multifunctional capacity and removed as waste). However, of organic electronics, chemists need to defect-free 3D processing of organic broaden their research focus beyond electronic structures remains a major charge transport and gain a better challenge to industry-scale manufacture. understanding of how molecular Engineers need to build on what has structure and interfacial behavior already been done with 2D lithography impacts not just electronic but also so that they can fabricate uniform 3D optical, magnetic, thermal and other structures in a controlled manner on a properties. nano-level, not just micron-level, scale.

Organic Electronics for a Better Tomorrow / 25

CONCLUSION the market and a multitude of device prototypes in development. The field will continue to grow, In 2004, it was predicted that chemists changing the way society interacts with would soon synthesize organic technology, as chemists, physicists, and semiconductors with charge-carrier other scientists and engineers address the mobilities greater than 10 cm2/Vs and research challenges identified by the organic photovoltaic cells with 10 2012 CS3 symposium participants. percent power conversion efficiencies. Multidisciplinary research and training Those predictions have come true. More programs that bring together scientists recently, it was predicted that organic and engineers from different fields of electronics would become a US$30 knowledge, as well as from different billion industry by 2015. While this sectors of activity (i.e., academia, more recent prediction may have been industry, government), will facilitate the overly optimistic, nonetheless the field collaborative effort needed to meet these of organic electronics clearly has made challenges. tremendous strides over the past few decades, with some devices already on

Organic Electronics for a Better Tomorrow / 26

REFERENCES nanocube-augmented carbon nanotube networks. ACS Nano 3(1):37-44.

Abidian MR, Ludwig KA, Marzullo TC, Diez-Perez I, Hihath J, Lee Y, et. al. et al. 2009. Interfacing conducting 2009. Rectification and stability of a polymer nanotubes with the central single molecular diode with controlled nervous system: chronic neural orientation. Nature Communications 1: recording using poly(3,4- 635-641. ethylenedioxythiophene) nanotubes. Advanced Materials 21(37):3764-3770. Drain CM, Nifiatis F, Vasenko A, Batteas JD. Porphyrin tessellation by Bachilo SM, Strano MS, Kittrell C, et al. design: mediated self-assembly of 2002. Structure-assigned optical spectra large arrays and tapes. Angewandte of single-walled carbon nanotubes. Chemie International Edition 37:2344- Science 298: 2361-2366. 2347.

Berrouard P, Najari A, Pron A, et al. Gabor NM, Zhong Z, Bosnick K, et al. 2012. Synthesis of 5-Alkyl[3,4- 2009. Extremely efficient multiple c]thienopyrrole-4,6-dione-based -hole pair generation in carbon polymers by direct heteroarylation. nanotube photodiodes. Science Angewandte Chemie International 325:1367-1371. Edition 52:2068-2072. Gather MC, Köhnen A, Falcou A, et al. Briseno AL, Aizenberg J, Han YJ, et al. 2007. Solution-processed full- 2005. Patterned growth of large oriented polymer OLED display fabricated by single crystals direct photolithography. Advanced on self-assembled monolayer templates. Functional Materials 17: 191-200 Journal of the American Chemical Society 127:12164-12165, Gather MC, Meerholz K, Danz N, Leosson K. 2010. Net optical gain in a Cai J, Ruffieux P, Jaafar R, et al. 2010. plasmonic waveguide embedded in a Atomically precise bottom-up fluorescent polymer. Nature Photonics 4: fabrication of graphene nanoribbons. 457-461. Nature 466(7305):470-473. Geim AK, Novoselov KS. 2007. The Chen W, Widawsky JR, Vazquez H, et rise of graphene. Nature Materials - 6:183-191. conjugated molecular junctions covalently bonded to gold electrodes. Haigh SJ, Gholinia A, Jalil R, et al. Journal of the American Chemical 2012. Cross-sectional imaging of Society 133:17160-17163. individual layers and buried interfaces of graphene-based heterostructures and Claussen JC, Franklin AD, ul Haque A, superlattices. Nature Materials 11:764- et al. 2009. Electrochemical biosensor of 767.

Organic Electronics for a Better Tomorrow / 27

Hau, SK, Yip H-L, Acton O, et al. 2008. Kanibolotsky AL, Perepichka IF, Interfacial modification to improve Skabara PJ. 2010. Star-shaped - inverted polymer solar cells. Journal of conjugated oligomers and their Materials Chemistry 18:5113-5119. applications in organic electronics and photonics. Chemical Society Reviews He Z, Zhong C, Hunag X, et al. 2011. 39:2695-2728. Simultaneous enhancement of open- circuit voltage, short-circuit current Kim JB, Allen K, Oh SJ, et al. 2010. density, and fill factor in polymer solar Small-molecule thiophene-C60 dyads as cells. Advanced Materials 23:4636- compatibilizers in inverted polymer solar 4643. cells. Chemistry of Materials 22:5762- 5773. Hodge SA, Bayazit MK, Coleman KS, Shaffer MS. 2012. Unweaving the Kim JB, Kim P, Pegard NC, et al. 2012. rainbow: a review of the relationship Wrinkles and deep folds as photonic between single-walled carbon nanotube structures in photovoltaics. Nature molecular structures and their chemical Photonics 6:327-332. reactivity. Chemical Society Reviews 41(12):4409-4429. Klauk H, Zschieschang U, Pflaum J, Halik M. 2007. Ultralow-power organic Hoeben FJM, Jonkheijm P, Meijer EW, complementary circuits. Nature Schenning APHJ. 2005. About 4455:745-748. supramolecular assemblies of π- conjugated systems. Chemical Reviews Kohn PP, Huettner SS, Komber HH et 105: 1491-1546 al. 2012. On the role of single regiodefects and polydispersity in Ju S-Y, Doll J, Sharma I, regioregular poly(3-hexylthiophene): Papadimitrakopoulos F. 2008. Selection defect distribution, synthesis of defect- of carbon nanotubes with specific free chains, and a simple model for the chiralities using helical assemblies of determination of crystallinity. Journal of flavin mononucleotide. Nature the American Chemical Society Nanotechnology 3:356-362. 134:4790-805.

Kagan CR, Breen, TL, Kosbar, LL. Kuribara K, Wang H, Uchiyama N, et al. 2001. Patterning organic-inorganic thin- 2012. Organic transistors with high film transistors using microcontact thermal stability for medical printed templates. Applied Physics applications. Nature Communications Letters 79:3536-3538. 3:Article Number 723.

Kaltenbrunner M, White MS, Glowacki Levendorf MP, Kim C-J, Brown B, et al. ED, et al. 2012. Ultrathin and 2012. Graphene and boron nitride lateral lightweight organic solar cells with high heterostructures for atomically thin flexibility. Nature Communications circuitry. Nature 488:627-632. 3:Article number 770. Li G, Shrotriya V, Huang J, et al. 2005. High-efficiency solution processable

Organic Electronics for a Better Tomorrow / 28

polymer photovoltaic cells by self- internal quantum efficiency approaching organization of polymer blends. Nature 100 %. Nature Photonics 3:297-302. Materials 4:864-868. Peet J, Kim JY, Coates E, et al. 2007. Li N, Z Chen, W Ren, F Li, H Cheng. Efficiency enhancement in low-bandgap 2012. Flexible graphene-based lithium polymer solar cells by processing with ion batteries with ultrafast charge and alkane dithiols. Nature Materials 6:497- discharge rates. Proceedings of the 500. National Academy of Sciences 109(43):17360-17365. Safont-Sempere MM, Fernández G, Würthner F 2011. Self-sorting Li Y, Sonar P, Singh SP, et al. 2011. phenomena in complex supramolecular Annealing-free high-mobility systems. Chemical Reviews 111: 5784- diketopyrrolopyrrole-quaterthiophene 5814. copolymer for solution-processed organic transistors. Journal of Saudari SR, Frail PR, Kagan CR. the American Chemical Society 133: Ambipolar transport in solution- 2198-2204. deposited transistors enhanced by of device Lv W, Tang D-M, He Y-B, et al. 2009. contacts. Applied Physics Letters Low-temperature exfoliated graphemes: 95:023301-023303. vacuum-promoted exfoliation and electrochemical energy storage. ACS Sekitani T, Noguchi Y, Hata K, et al. Nano 3(11): 3730-3736 2008. A rubberlike stretchable active matrix using elastic conductors. Science McCulloch I, Heeney M, Bailey C, et al. 321(5895):1468-1472. 2006. Liquid-crystalline semiconducting polymers with high charge-carrier Sekitani T, Zschieschang U, Klauk H, mobility. Nature Materials 5:328-333. Someya T. 2010. Flexible organic transistors and circuits with extreme Müller CD, Falcou A, Reckefuss N, et bending stability. Nature Materials al. 2003. Multi-color organic light- 9:1015-1002. emitting displays by solution processing. Nature 421: 829-833. Sirringhaus H, Brown PJ, Friend RH, et al. 1999. Two-dimensional charge Novoselov KS, Falko VI, Colombo PR. transport in self-organized high-mobility 2012. A roadmap for graphene. Nature conjugated polymers. Nature 401:685- 490:192-200. 688.

Novoselov KS, Geim AK, Morozov SV, Sokolov AN, Tee BC, Bettinger CJ, et et al. 2004. effect in al. 2012. Chemical and engineering atomically thin carbon films. Science approaches to enable organic field-effect 306:666-669 transistors for electronic skin applications. Accounts of Chemical Park SH, Roy A, Beaupre S, et al. 2009. Research 45(3):361-71. Bulk heterojunction solar cells with

Organic Electronics for a Better Tomorrow / 29

Sun D, Timmermans MY, Tian Y, et al. 2011. Flexible high-performance carbon Würthner F, Meerholz K. 2010. Systems nanotube integrated circuits. Nature chemistry approach in organic Nanotechnology 6:156-161. photovoltaics. Chemistry: A European Journal. 16(31):9366-9373 Torrisi F, Hasan T, Wu W, et al. 2012. Inkjet-printed graphene electronics. ACS Würthner F., Stolte M. 2011. Nano 6:2992-3006. Naphthalene and diimides for organic transistors, Chemical United Nations [UN] System Task Team Communications 2011, 47, 5109-5115. on the Post-2015 UN Development Agenda. Realizing the Future We Want Xu B, Tao NJ. 2003. Measurement of for All. Report to the Secretary-General. single-molecule resistance by repeated https://docs.google.com/gview?url=http: formation of molecular junctions. //sustainabledevelopment.un.org/content/ Science 301:1221-1223. documents/614Post_2015_UNTTreport. pdf&embedded=true. Yoo JE, Lee KS, Garcia A, et al. 2010. Directly patternable, highly conducting Uwe H, Bunz F, Menning S, Martin N. polymers for broad applications in 2012. Para-connected cyclophenylenes organic electronics. Proceedings of the and hemispherical polyarenes: building National Academy of Sciences blocks for single-walled carbon 107:5712-5717. nanotubes? Angewandte Chemie, International Edition 51:2–10. Yoon M-H, Fachetti A, Marks TJ. 2005.

Wang QH, Hersam MC. 2009. Room- for low-voltage organic thin-film temperature molecular-resolution transistors. Proceedings of the National characterization of self-assembled Academy of Sciences 102:4678-4682. organic monolayers on epitaxial graphene. Nature Chemistry 1: 206-211. Zschieschang U, Yamamoto T, Takimiya K, et al. 2011. Organic Woll A, Mukherjee MP, Levendorf EL, electronics on banknotes. Advanced et al. 2011. Oriented 2D covalent Materials 23(5):654-658. organic framework thin films on single- layer graphene. Science 332:228-231

Organic Electronics for a Better Tomorrow / 30

2012 CS3 Participants

Name Institution Title

China Delegation

Xi Zhang (Chair) Tsinghua University, Professor of Chemistry Beijing He Tian East China University of Professor of Chemistry and Science and Technology, Molecular Engineering Shanghai Lixiang Wang Chinese Academy of Professor, Changchun Sciences, Changchun Institute of Applied Chemistry Jian Pei Peking University, Beijing Professor of Chemistry Jin Zhang Peking University, Beijing Professor of Chemistry Zhigang Shuai (liaison) Tsinghua University, Professor Chemistry Beijing Yunqui Liu Chinese Academy of Sciences, Beijing

Germany Delegation

Peter Bäuerle (chair) Ulm University, Ulm Director, Institute of Organic Chemistry II and Advanced Materials Frank Würthner University Würzburg, Professor, Institute of Würzburg Organic Chemistry Klaus Meerholz University of Cologne, Professor, Institute of Cologne Physical Chemistry Stefan Hecht Humboldt-Universität zu Professor, Laboratory of Berlin, Berlin Organic Chemistry and Functional Materials, Department of Chemistry Andreas Hirsch University Erlangen- Professor/Chair, Organic Nuremberg, Erlangen Chemistry Horst Hahn Karlsruhe Institute of Executive Director Technology, Eggenstein- Leopoldshafen Hans-Georg Weinig German Chemical Society Head Education and (liaison) Science

Organic Electronics for a Better Tomorrow / 31

Markus Behnke German Research Program Director Foundation (DFG)

Japan Delegation

Takuzo Aida (chair) University of Tokyo, Professor, Departments of Tokyo Chemistry and Biotechnology, School of Engineering Yoshiharu Sato Mitsubishi Chemical Senior Researcher, Group Science and Photovoltaics Project Technology Research Center, Inc., Tokyo Mitsuo Sawamoto Graduate School of Professor, Department of Engineering, Kyoto University, Kyoto Takao Someya School of Engineering, Professor, Department of University of Tokyo, Electrical Engineering Tokyo Kazuo Takimiya Graduate School of Professor, Department of Engineering, Hiroshima Applied Chemistry University, Higashi- Hiroshima Masahiro Yamashita Graduate School of Professor, Department of Science, Tohoku Chemistry University, Sendai, Miyagi Nobuyuki Kawashima Chemical Society of Japan, Executive Director and (liaison) Tokyo Secretary General Mitsuhiko Shionoya Japan Society for the Graduate School of Promotion of Science Science, University of (JSPS), Tokyo Tokyo

United Kingdom Delegation

Peter Skabara (chair) University of Strathclyde, Professor of Materials Glasgow, Scotland Chemistry Stephen Yeates University of Manchester, Professor of Polymer Manchester, England Chemistry Karl Coleman Durham University, Reader, Department of Durham, England Chemistry Martin Heaney Imperial College London, Reader of Materials London, England Chemistry, Department of Chemistry

Organic Electronics for a Better Tomorrow / 32

Andrew Monkman Durham University, Director, Photonic Durham, England Materials Centre, Department of Physics Richard Walker (liaison) Royal Society of Science Executive Chemistry, Cambridge, England Clare Bumphrey Engineering and Physical Physical Sciences Portfolio Sciences Research Council, Manager Swindon, England

United States Delegation

Cherie Kagan (chair) University of Professor, Departments of Pennsylvania, Philadelphia, Chemistry, Electrical and Penn. Systems Engineering, and and Engineering Lynn Loo Princeton University, Professor, Department of Princeton, New Jersey Chemical and Biological Engineering Claudia Arias University of California, Acting Associate Berkeley Professor, Department of Electrical Engineering and Computer Sciences Colin Nuckolls Columbia University, New Professor, Department of York, New York Chemistry James Batteas Texas A&M University, Professor, Department of College Station, Texas Chemistry Jiwoong Park Cornell University, Ithaca, Asst. Professor, New York Department of Chemistry and Chemical Biology Dat Tran (liaison) American Chemical International Activities Society, Washington, D.C. Manager, Office of International Activities Francisco Gomez American Chemical Assistant Director, Office Society, Washington, D.C. of International Activities Zeev Rosenzweig National Science Program Director Foundation, Arlington, Virginia Leslie Pray (science writer) Independent Consultant, Los Angeles, California

Organic Electronics for a Better Tomorrow / 33