While conventional electronics like computers and smartphones are built around silicon integrating billions of transistors and is manufactured using complex, costly and wasteful processes in multi-billion dollar foundries , organic electronics aim to replace this by “organic” semiconductors which are long chains of thousands of repeating molecules (a plastic), made with materials based on carbon. Organic semiconductors can be made to be soluble, and can be turned into an ink. This means it’s possible to print electronic circuits, with the potential to manufacture components as fast as printing newspapers.
Organic electronics is a field of materials science concerning the design, synthesis, characterization, and application of organic molecules or polymers that show desirable electronic properties such as conductivity. Unlike conventional inorganic conductors and semiconductors, organic electronic materials are constructed from organic (carbon-based) molecules or polymers using synthetic strategies developed in the context of organic chemistry and polymer chemistry.
One of the promised benefits of organic electronics is their potential low cost compared to traditional electronics. Attractive properties of polymeric conductors include their electrical conductivity (which can be varied by the concentrations of dopants) and comparatively high mechanical flexibility. Challenges to the implementation of organic electronic materials are their inferior thermal stability, high cost, and diverse fabrication issues.
Conductive organic materials
The biggest advantage of conductive polymers is their processability, mainly by dispersion. Among well-known conducting polymers, polyacetylene and poly(phenylene vinylene) are synthesized almost exclusively by chemical polymerization or from precursor route. Polyheterocycles such as polythiophene or polypyrrole are synthesized by both chemical and electrochemical polymerization.
Organic conductive materials can be grouped into two main classes: polymers and conductive molecular solids and salts. Polycyclic aromatic compounds such as pentacene and rubrene often form semiconducting materials when partially oxidized.
Conductive polymers are often typically intrinsically conductive or at least semiconductors. They sometimes show mechanical properties comparable to those of conventional organic polymers. Both organic synthesis and advanced dispersion techniques can be used to tune the electrical properties of conductive polymers, unlike typical inorganic conductors. Well-studied class of conductive polymers include polyacetylene, polypyrrole, polythiophenes, and polyaniline. Poly(p-phenylene vinylene) and its derivatives are electroluminescent semiconducting polymers. Poly(3-alkythiophenes) have been incorporated into prototypes of solar cells and transistors.
A semiconductor made of synthetic polymer such as an LED or transistor. Such “conjugated polymers” are a plastic material that changes from being an insulator to a semiconductor after being doped. Conductive polymers or, more precisely, intrinsically conducting polymers (ICPs) are organic polymers that conduct electricity. Such compounds may have metallic conductivity or can be semiconductors.
An OLED (organic light-emitting diode) consists of a thin film of organic material that emits light under stimulation by an electric current. A typical OLED consists of an anode, a cathode, OLED organic material and a conductive layer
In the emerging field of organic printable electronics, such as OLEDs and organic photovoltaics (OPVs), there is a significant need for improved organic conducting and semiconducting materials. An emerging class of electrically conductive plastics called “radical polymers” may bring low-cost, transparent solar cells, flexible and lightweight batteries and ultrathin antistatic coatings for consumer electronics and aircraft.
“It’s a polymer glass that conducts charge, which seems like a contradiction because glasses are usually insulators,” said Bryan Boudouris, an assistant professor of chemical engineering at Purdue University. The polymer is easy to manufacture, resembling Plexiglas, an inexpensive transparent plastic found in numerous products. However, unlike Plexiglas it conducts electricity. “We make billions of tons of plastic every year,” Boudouris said. “So imagine if you could produce that same kind of material at that same scale but now it has electronic properties.”
Organic Solar cells
Organic solar cells could cut the cost of solar power compared with conventional solar-cell manufacturing. Silicon thin-film solar cells on flexible substrates allow a significant cost reduction of large-area photovoltaics for several reasons:
- The so-called ‘roll-to-roll’-deposition on flexible sheets is much easier to realize in terms of technological effort than deposition on fragile and heavy glass sheets.
- Transport and installation of lightweight flexible solar cells also saves cost as compared to cells on glass.
Inexpensive polymeric substrates like polyethylene terephthalate (PET) or polycarbonate (PC) have the potential for further cost reduction in photovoltaics. Protomorphous solar cells prove to be a promising concept for efficient and low-cost photovoltaics on cheap and flexible substrates for large-area production as well as small and mobile applications.
Researchers have established the solid-state electrical properties of one such polymer, called PTMA, which is about 10 times more electrically conductive than common semiconducting polymers. The PTMA is in a class of electrically active polymers that could bring inexpensive transparent solar cells; antistatic and antiglare coatings for cellphone displays; antistatic coverings for aircraft to protect against lightning strikes; flexible computer flash drives; and thermoelectric devices, which generate electricity from heat.
The polymers have seen commercial use in new types of batteries. However, finding widespread practical applications for the polymers will require increasing the conductivity another 100 to 1,000 times, Boudouris said. Recent research findings were detailed in a paper published online in May in the journal Macromolecules. A review article on the subject appeared in September in the same journal and is featured on the cover.
Polymers are strings of molecules with a central backbone and may contain side chains called “pendant groups” that dangle from the central structure. In radical polymers, it’s these pendant groups that allow charge to be transported, conducting current. To create the radical polymer, the researchers used a procedure called deprotection, which involves replacing a specific hydrogen atom in the pendant group with an oxygen atom, converting it into a so-called radical group. “We just finally studied deprotection in a way others had not to learn how it affects the electronic properties of the radical polymers,” Boudouris said.
Electrons surround an atom’s nucleus in “shells” and these electrons are usually paired. The oxygen atom in PTMA, however, has one unpaired electron in its outer shell, making it amendable to transporting charge. “You have to control the deprotection process very well because it makes the conductivity vary by orders of magnitude,” he said. The researchers have determined that the deprotection step can lead to four distinct chemical functionalities of the radical polymer, two of which are promising for increasing the conductivity of the polymer. “So manipulating the reaction conditions for this deprotection step, and monitoring closely the resultant chemical functionalities, is critical in tuning the electrical properties of radical polymers,” Boudouris said.
Organic field-effect transistor
An Organic field-effect transistor is a field-effect transistor utilizing organic molecules or polymers as the active semiconducting layer. A field-effect transistor (FET) is any semiconductor material that utilizes electric field to control the shape of a channel of one type of charge carrier, thereby changing its conductivity. Two major classes of FET are n-type and p-type semiconductors, classified according to the charge type carried. In the case of organic FETs (OFETs), p-type OFET compounds are generally more stable than n-type due to the susceptibility of the latter to oxidative damage.
As for OLEDs, some OFETs are molecular and some are polymer-based system. Rubrene-based OFETs show high carrier mobility of 20–40 cm2/(V·s). Another popular OFET material is Pentacene. Due to its low solubility in most organic solvents, it’s difficult to fabricate thin film transistors (TFTs) from pentacene itself using conventional spin-cast or, dip coating methods, but this obstacle can be overcome by using the derivative TIPS-pentacene.
Breakthrough in organic electronics
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.
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 the 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.
Making Plastic More Transparent While Also Adding Electrical Conductivity
In an effort to improve large touchscreens, LED light panels and window-mounted infrared solar cells, researchers at the University of Michigan have made plastic conductive while also making it more transparent. They provide a recipe to help other researchers find the best balance between conductivity and transparency by creating a three-layer anti-reflection surface. The conductive metal layer is sandwiched between two “dielectric” materials that allow light to pass through easily. The dielectrics reduce the reflection from both the plastic and metal layer between them.
“We developed a way to make coatings with high transparency and conductivity, low haze, excellent flexibility, easy fabrication and great compatibility with different surfaces,” said Jay Guo, U-M professor of electrical engineering and computer science, who led the work. Previously, Guo’s team had shown that it was possible to add a layer of metal onto a plastic sheet to make it conductive—a very thin layer of silver that, by itself, reduced the transmission of light by roughly 10%.
Light transmission through plastic is a little lower than through glass, but its transparency can be improved with anti-reflection coatings. Guo and his colleague Dong Liu, a visiting professor at U-M from Nanjing University of Science and Technology, realized that they could make an anti-reflection coating that was also conductive. “It was taken for granted that the transmittance of the conductor is lower than that of the substrate, but we show that this is not the case,” said Chengang Ji, first author of the study in Nature Communications, who worked on the project as a Ph.D. student in electrical and computer engineering. Ji received his doctorate from U-M in 2019.
The dielectrics chosen by the team in this case are aluminum oxide and zinc oxide. On the side closest to the light source, the aluminum oxide reflects less light back to the source than the plastic surface would. Then comes the metal layer, composed of silver with a tiny amount of copper in it, just 6.5 nanometers thick, and then zinc oxide helps guide the light into the plastic surface. Some light still gets reflected back where the plastic meets the air on the opposite side, but overall, the light transmission is better than the plastic alone. The transmittance is 88.4%, up from 88.1% for the plastic alone.
With the theory results, the team anticipates that other researchers will be able to design similar sandwich-style flexible, highly transparent conductors, which allow even more light through than the plastic alone. “We tell people how transparent a dielectric-metal-dielectric conductor could be, for a target electrical conductance. We also tell them how to achieve this high transmittance step-by-step,” Liu said.
Organic or Plastic Electronics Market
The global organic electronic market size is expected to reach from $46.12 billion in 2019 to $159.11 billion by 2027, growing at a CAGR of 21.0% from 2020 to 2027. Organic electronics are unlike conventional inorganic semiconductors. Organic electronic materials are engineered using organic (carbon-based) polymers or molecules using artificial technology developed in the context of organic & polymer chemistry.
Increase in demand due to adoption of technologies supporting sustainable development, demand for various applications, and need of organic electronic in latest technologies are the factors that drive the organic electronic market growth. Whereas, degradation of efficiency of organic electronics after a period and technical in-compatibility hampers the organic electronic market growth. However, the increase in R&D activities for various applications is expected to create organic electronic market opportunity.
Over the years the development of eco-friendly technologies and their adoption has picked up the rate of its penetration. The use of clean energy such as organic batteries, use of biodegradable materials for technological developments such as OLEDs increases the market demand for organic electronics. As, organic devices are easier to dispose in environment and thus, are also promoted by governments across the world. Further, the organic electronics operates on low energy, thereby, providing energy saving solutions.
The need of organic films in display screens for enhanced performance in terms of color, brightness, contrast and refresh rates rises the market demand. Modern day lighting and display technologies are major applications for organic electronics. Organic semiconductors are also in high demand for smart textiles. In the healthcare sector, organic semiconductors have application in skin cancer treatment, which increase the organic electronic market demand.
Further, the advancement of organic electronics has increased its demand in the consumer electronics vertical. The organic electronics offers the manufacturers and developers with the advantages of being light weight and flexibility in the organic electronic material when compared to inorganic material. Therefore, the organic batteries and organic films for displays can be installed in devices with newer sophisticated designs such as that of foldable smartphones, curved display TVs, among other such electronic devices.
The global plastics in consumer electronics market size is expected to reach USD 7.70 billion by 2028, according to a new report by Grand View Research, Inc. The market is expected to expand at a CAGR of 3.8% from 2021 to 2028. Increasing demand from the smartphone & wearable products industry is anticipated to fuel the demand for plastics in consumer electronics. The smartphone market offers opportunities for usage of a variety of plastic resins, such as Polycarbonate (PC), Acrylonitrile Butadiene Styrene (ABS), and Polymethyl Methacrylate (PMMA), as they are used for manufacturing housings for electronic devices, mounting frames, display frames, and vibration cushions that are lightweight and durable.
Proximity to raw material suppliers and low labor costs are attracting consumer electronics manufacturers in China. The presence of several key consumer electronics manufacturers is anticipated to create significant demand for plastics. Furthermore, increasing demand for appliances in India is anticipated to boost product demand across the electronics industry. In addition, rapid urbanization is expected to propel the demand for mobile phones, laptops, television, and other electronic appliances across India.
As per the organic electronic market analysis, the market is segmented into material, application and region. The material is further categorized into semiconductor, conductive and dielectric & substrate. The application segment is classified into display, lighting, battery, conductive ink and others. Region wise, the market is analyzed across North America, Europe, Asia-Pacific, and LAMEA.
The organic electronics use various materials such as semiconductor material, conductive material and dielectric & substrate material for construction. Further, these are used in various applications such as that of displays, lighting, battery, conductive ink and others, which increases the demand in the organic electronics market.
Organic semiconductors are non-metallic materials that offer semiconducting properties. These semiconductors have several advantages as compared to inorganic semiconductors such as mechanical flexibility, lightweight, and low cost; thereby offering opportunity to develop devices using low cost fabrication techniques. Rise in awareness for sustainable development and as organic semiconductors are biodegradable; thus, are increasingly preferred over their counterparts, thereby, increasing the organic electronic market demand. The dielectric material creates demand and opportunities for various applications in consumer electronics, automotive, digital signage, medical and security.
The advancement of display technology creates demand in the organic electronic industry Organic-LEDs (OLEDs) among the latest and most advanced display technologies. OLED displays are used in mobile phones, laptops, most prominently in televisions and other display panel electronic devices. The OLED display offers various advantages to the users which are enhanced image quality in terms of better contrast, higher brightness, fuller viewing angle, a wider color range, much faster refresh rates, and lower power consumptions. Therefore, increasing advantages have also allowed the displays to be ultra-thin, flexible, foldable and transparent displays.
Organic electronics however, have few disadvantages, one among them is the degradation of organic components over time, which reduces their functional efficiency. For instance, it is observed that OLED TVs after a period tend to reduce quality of display output, in terms of brightness and vibrant colors.
Key players which have a major organic electronic market share include AGC INC., BASF SE, COVESTRO AG, Evonik Industries AG, H.C. Starck Inc., Heliatek GmbH, Merck Group, Novaled GmbH, POLYIC GMBH & CO. KG and Sumitomo Corporation, which are profiled in this report.
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