ACKNOWLEDGEMENT 

A report is never the sole of product of the person whose name has appeared on the cover. Even the best effort may not prove successful without the Proper guidance. For a good report one needs proper time, energy, efforts, patience and acknowledge. But without any guidance it remains unsuccessful. I have done this project to the best of my abilities with all shortcomings in me and I hope that it will serve its purpose. 

 I owe a deep sense of gratitude to Mr. JASPAL JINDAL(HOD of ECE) for allowing me to undergo this project and for his valuable guidance, keen interest and constant supervision by which I have completed this project with my best considerations. 

We feel good pleasure to express my sincere thanks to Ms. PREETI BANSAL, Mrs. NEERAJ and Mr. SATYAM project Coordinator. It has been my high privilege to work under their guidance, which helped me immensely towards completing my project. In the end, I would like to thank all the faculty for their support, which helped me in completing this project.

       

CONTENTS  

ABSTRACT INTRODUCTION HISTORY FEATURES ORGANIC ELECTRONIC DEVICES PLASTIC SOLAR CELLS MANUFACTURING PLASTIC ELECTRONICS ORGANIC LED Working principle Material technologies Structure Advantages and Disadvantages ORGANIC THIN FILM TRANSISTORS TOWARDS WOVEN LOGIC FROM OE THE FUTURE ROLE OF PRINTING PRESENT, FUTURE DEVELOPMENTS APPLICATIONS AND FEATURES OF OE CONCLUSION

 

         

ABSTRACT 

 

Bhawani Shankar Anangpuria Charitable Trust was established in July 1992 under the able stewardship of its founder Chairman Shri O.P. Gupta. The trust was founded with a wide perspective of committed contribution to social improvement through comprehensive ultra modern education and state-of-art medical and health services.

The trust has established four Par excellence educational institutions in the field of Technology, Management, Pharmacy&Education along with a fully equipped modern medical hospital and research centre. The aim of developing a number of institutions in a centralised campus was to give myriad choice to the students to enable them to select a course of his/her choice in his/her studies. All this could be achieved through sincere and concentrated efforts of promoters ,and dedicated staff and has become synonymous with excellence and perfection within a very short period of its inception. It will not be an exaggeration to say that these pace setting institutions are going to be 'the beacon light' for other institutions of the country.

The dynamism and resilience of Sh. O.P. Gupta, the Chairman, Sh. Vinay Gupta, the Vice Chairman of the trust & value based personality of Dr. D.C Dayal, Director of B. S. Anangpuria institutions has helped the institutions to tread the path of academic excellence coupled with value orientation.

  

 

INTRODUCTION 

Organic electronics, plastic electronics or polymer electronics, is a branch of electronics that deals with conductive polymers, plastics, or small molecules. It is called 'organic' electronics because the polymers and small molecules are carbon-based, like the molecules of living things. This is as opposed to traditional electronics (or metal electronics) which relies on inorganic conductors such as copper or silicon.

Polymer electronics are laminar electronics, that also includes transparent electronic package and paper based electronics.

In addition to organic Charge transfer complexes, technically, electrically conductive polymers are mainly derivatives of polyacetylene black (the "simplest melanin"). Examples include PA (more specifically iodine-doped trans-polyacetylene); polyaniline: PANI, when doped with a protonic acid; and poly (dioctyl-bithiophene): PDOT. 

   

    

HISTORY 

Alan J. Heeger, Alan G. MacDiarmid, and Hideki Shirakawa are credited for the discovery and development of highly-conductive polymers (at least of the rigid-backbone "polyacetylene" class) and were jointly awarded the Nobel Prize in Chemistry in 2000 for the 1977 discovery and development of oxidized, iodine-doped polyacetylene.

Interestingly, this prize passed over the much earlier discovery of highly-conductive organic Charge transfer complexes, some of which are even superconductive. Similarly, the first demonstration of high-conductivity in the linear backbone polymers was a series of papers by Weiss et al. in 1963. These workers reported a conductivity of 1 S/cm in a similarly iodine-"doped" and oxidized polypyrroleblack.

Conduction mechanisms in such materials involve resonance stabilization and delocalization of pi electrons along entire polymer backbones, as well as mobility gaps, tunnelling, and phonon-assisted hopping.

Technology for plastic electronics on thin and flexible plastic substrates was developed at Cambridge University’s Cavendish Laboratory in the 1990s. In 2000, Plastic Logic was spun out of Cavendish Laboratory to develop a broad range of products using the plastic electronics technology.

      

FEATURES 

 

Conductive polymers are lighter, more flexible, and less expensive than inorganic conductors. This makes them a desirable alternative in many applications. It also creates the possibility of new applications that would be impossible using copper or silicon.

Organic electronics not only includes organic semiconductors, but also dielectrics, conductors and light emitters.

New applications include smart windows and electronic paper. Conductive polymers are expected to play an important role in the emerging science of molecular computers.

In general organic conductive polymers have a higher resistance and therefore conduct electricity poorly and inefficiently, as compared to inorganic conductors. Researchers currently are exploring ways of "doping" organic semiconductors, like melanin, with relatively small amounts of conductive metals to boost conductivity. However, for many applications, inorganic conductors will remain the only viable option.

Organic electronics can be printed.      

ORGANIC ELECTRONIC DEVICES

Organics-based flexible displayA 1972 paper in the journal Science proposed a model for electronic conduction in the melanin. Historically, melanin is another name for the various oxidized polyacetylene, polyaniline, and Polypyrrole "blacks" and their mixed copolymers, all commonly-used in present day organic electronic devices. E.g., some fungal melanins are pure polyacetylene. This model drew upon the theories of Neville Mott and others on conduction in disordered materials. Subsequently, in 1974, the same workers at the Physics Department of The

University of Texas M. D. Anderson Cancer Center reported an organic electronic device, a voltage-controlled switch.

Their material also incidentally demonstrated "negative differential resistance", now a hall-mark of such materials. A contemporary news article in the journal Nature noted this materials "strikingly high conductivity'. These researchers further patented batteries, etc. using organic semi conductive materials. Their original "gadget" is now in the Smithsonian's collection of early electronic devices.

This work, like that the decade-earlier report of high-conductivity in a polypyrrole, was "too early" and went unrecognized outside of pigment cell research until recently. At the time, few except cancer research institutes were interested in the electronic properties of such polymers, which are applicable to the treatment of melanoma. 

PLASTIC SOLAR CELLS  Organic solar cells could cut the cost of solar power by making use of inexpensive organic polymers rather than the expensive crystalline silicon used in most solar cells. What's more, the polymers can be processed using low-cost equipment such as ink-jet printers or coating equipment employed to make photographic film, which reduces both capital and manufacturing costs 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:

1. 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.

2. Transport and installation of lightweight flexible solar cells also saves cost as compared to cells on glass.

Inexpensive polymeric substrates like polyethylene terephtalate(PET) or polycarbonate (PC) would be a way out towards 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.

One beauty of printed electronics is that the different electrical and electronic components can be printed on top of each other, saving space and increasing reliability and sometimes they are all transparent. One ink must not damage another and low temperature annealing is vital if low-cost flexible materials such as paper and plastic film are to be used. 

 

MANUFACTURING PLASTIC ELECTRONICS 

The "heart" of modern electronics are microchips - circuits and wiring "diagrams" are designed and micro-miniaturized to the point that thousands or even millions of circuits are contained in a one-inch square chip which is "burned" (or etched) onto ultra-thin inorganic materials like refined silicon using very high temperatures.

Plastic electronics, on the other hand, follow a different manufacturing process. The process starts with the manufacture of large sheets of PET (polyethylene terephthalate) plastic - the flexible but tough material used in the production of plastic bottles. Circuits are then printed on these sheets using ink-jet printers or using techniques much like those used to print magazines and newspapers - resulting in a process that is cheap, easy to do and faster to produce.

The plastic circuits will be used as the "active-matrix back panes" for large but flexible electronic displays. In an active-matrix display, every dot on the display is managed by a switching element such as thin film transistors (TFT) and the signals on an array of intersecting row and column electrodes. Prior to plastic electronics, these TFTs have been produced using amorphous silicon deposited on a rigid glass substrate at high temperature through a complex series of production procedures.

It is the collection of switching elements and row-column electrodes which are put together on a substrate to form the active-matrix backpane, which is then combined with different front-plane technologies (e.g., Liquid Crystal Diode or LCD screens) to form the display.

For many electronic readers, the best front plane technology is electronic paper which looks like paper and only uses the unit's power when the image shifts or changes (a property called bi-stability). Sony Reader and the iRex Illiad both use electronic paper for their display screens.

Electronic paper, however, loses its thinness and flexibility when combined with a glass-based silicon backpane. The flexible backpane technology of plastic electronics allows the reader device to become flexible, light, thin and robust enough for a wide range of uses where no paper has gone before and to include large data storage capacities.

ORGANIC LED

A 3.8 cm (1.5 in) OLED display

An organic light emitting diode (OLED), also organic electro luminescent device (OELD), is a light-emitting diode (LED) whose emissive electroluminescent layer is composed of a film of organic compounds. This layer of organic semiconductor material is formed between two electrodes, where at least one of the electrodes is transparent.

Such devices can be used in television screens, computer monitors, small, portable system screens such as cell phones and PDAs, watches, advertising, information and indication. OLEDs can also be used in light sources for general space illumination, and large-area light-emitting elements. Due to the younger stage of development, OLEDs typically emit less light per unit area than inorganic solid-state based LEDs which are usually designed for use as point-light sources.

In the context of displays, OLEDs have certain advantages over traditional liquid crystal displays (OLCDs). OLED displays do not require abacklight to function. Thus, they can display deep black levels and can be thinner and lighter than LCD panels. OLED displays also naturally achieve higher contrast ratios than either LCD screens using cold cathode fluorescent lamps (CCFLs) or the more recently developed LED backlights in conditions of low ambient light such as dark rooms.

Working principle

A typical OLED is composed of an emissive layer, a conductive layer, a substrate, and both anode and cathode terminals. The layers are made of organic molecules that conduct electricity. The layers have conductivity levels ranging from insulators to conductors, so OLEDs are considered organic semiconductors.

The first, most basic OLEDs consisted of a single organic layer, for example the first light-emitting polymer device synthesised by Burroughs et al. involved a single layer of poly (p-phenylene vinylene). Multilayer OLEDs can have more than two layers to improve device efficiency. As well as conductive properties, layers may be chosen to aid charge injection at electrodes by providing a more gradual electronic profile, or block a charge from reaching the opposite electrode and being wasted.

Schematic of a 2-layer OLED: 1. Cathode (−), 2. Emissive Layer, 3. Emission of radiation, 4. Conductive Layer, 5. Anode (+)

A voltage is applied across the OLED such that the anode is positive with respect to the cathode. This causes a current of electrons to flow through the device from cathode to anode. Thus, the cathode gives electrons to the emissive layer and the anode withdraws electrons from the conductive layer; in other words, the anode gives electron holes to the conductive layer.

Soon, the emissive layer becomes negatively charged, while the conductive layer becomes rich in positively charged holes. Electrostatic forces bring the electrons and the holes towards each other and they recombine. This happens closer to the emissive layer, because in organic semiconductors holes are more mobile than electrons. The recombination causes a drop in the energy levels of electrons, accompanied by an emission of radiation whose frequency is in the visible region. That is why this layer is called emissive.

Material technologies

Small molecules

Efficient OLEDs using small molecules were first developed at Eastman Kodak by Dr. Ching W. Tang. The production of small-molecule displays often involves vacuum deposition, which makes the production process more expensive than other processing techniques. Since this is typically carried out on glass substrates, these displays are also not flexible, though this limitation is not inherent to small-molecule organic materials. The term OLED traditionally refers to this type of device, though some are using the term SM-OLED.

Molecules commonly used in OLEDs include organo-metallic chelates (for example Alq3, used in the first organic light-emitting device) and conjugated dendrimers.

Contrary to polymers, small molecules can be evaporated and therefore very complex multi-layer structures can be constructed. This high flexibility in layer design is the main reason for the high efficiencies of the SM-OLEDs.

Polymer light-emitting diodes (PLED), also light-emitting polymers (LEP), involve an electroluminescent conductive polymer, also light emitting polymer (LEP), that emits light when connected to an external voltage source. They are used as a thin film for full-spectrum colour displays and require a relatively small amount of power for the light produced. No vacuum is required, and the emissive materials can be applied on the substrate by a technique derived from commercial inkjetprinting. The substrate used can be flexible, such as PET. Thus flexible PLED displays, also called Flexible OLED (or FOLED), may be produced inexpensively.

Applications of OLEDs in solid state lighting require the achievement of high brightness with good CIE coordinates (for white emission). The use of macromolecular species like polyhedral oligomeric silsesquioxanes (POSS) in conjunction with the use of phosphorescent species such as Ir for printed OLEDs has exhibited brightnesses as high as 10,000 cd/m2.

  Phosphorescent materials

Phosphorescent OLED (PHOLED) uses the principle of electrophosphorescence to convert electrical energy in an OLED into light in a highly efficient manner.

Structure

Bottom or top emission

Bottom emission uses a transparent or semi-transparent bottom electrode to get the light through a transparent substrate. Top emission uses a transparent or semi-transparent top electrode emitting light directly. Top-emitting OLEDs are better suited for active-matrix applications as they can be more easily integrated with a non-transparent transistor backplane.

Transparent OLED

Transparent organic light-emitting device (TOLED) use transparent or semi-transparent contacts on both sides of the device to create displays that can be made to be both top and bottom emitting (transparent). TOLEDs can greatly improve contrast, making it much easier to view displays in bright sunlight. This technology can be used in Head-up displays, smart windows or augmented reality applications.

Stacked OLED

Stacked OLED (SOLED) uses a pixel architecture that stacks the red, green, and blue subpixels on top of one another instead of next to one another, leading to substantial increase in gamut and color depth, and greatly reducing pixel gap. Currently, other display technologies have the RGB (and RGBW) pixels mapped next to each other decreasing potential resolution.

Inverted OLED

In contrast to a conventional OLED, in which the anode is placed on the substrate, an Inverted OLED (IOLED) uses a bottom cathode that can be connected to the drain end of an n-channel TFT especially for the low cost amorphous silicon TFT backplane useful in the manufacturing of AMOLED displays.

Advantages

The different manufacturing process of OLEDs lends itself to several advantages over flat-panel displays made with LCD technology.

Although the method is not currently commercially viable for mass production, OLEDs can be printed onto any suitable substrate using an inkjet printer or even screen printing technologies, they could theoretically have a lower cost than LCDs or plasma displays. However, it is the fabrication of the substrate that is the most complex and expensive process in the production of a TFT LCD, so any savings offered by printing the pixels is easily cancelled out by OLED's requirement to use a more costly P-Si (or LTPS) substrate - a fact that is born out by the significantly higher initial price of AMOLED displays than their TFT LCD competitors. A mitigating factor to this price differential going into the future is the cost of retooling existing lines to produce AMOLED displays over LCD's to take advantage of the economies of scale afforded by mass production.

Use of flexible substrates could open the door to new applications such as roll-up displays and displays embedded in fabrics or clothing.

OLEDs can enable a greater artificial contrast ratio (both dynamic range and static, measured in purely dark conditions) and viewing angle compared to LCDs because OLED pixels directly emit light. OLED pixel colours appear correct and unshifted, even as the viewing angle approaches 90 degrees from normal. LCDs filter the light emitted from a backlight, allowing a small fraction of light through so they cannot show true black, while an inactive OLED element produces no light and consumes no power.

OLEDs can also have a faster response time than standard LCD screens. Whereas LCD displays are capable of a 1ms response time or less offering a frame rate of 1,000Hz or higher, an OLED can theoretically have less than 0.01ms response time enabling 100,000Hz refresh rates.

Disadvantages

  Lifespan

The biggest technical problem for OLEDs is the limited lifetime of the organic materials. In particular, blue OLEDs historically have had a lifetime of around 14,000 hours to half original brightness (five years at 8 hours a day) when used for flat-panel displays, which is lower than the typical lifetime of LCD, LED or PDPtechnology—each currently rated for about 60,000 hours to half brightness, depending on manufacturer and model. However, some manufacturers displays aim to increase the lifespan of OLED displays, pushing their expected life past that of LCD displays by improving light outcoupling, thus achieving the same brightness at a lower drive current.

In 2007, experimental OLEDs were created which can sustain 400 cd/m² of luminance for over 198,000 hours for green OLEDs and 62,000 hours for blue OLEDs.

Color balance issues

Additionally, as the OLED material used to produce blue light degrades significantly more rapidly than the materials that produce other colors; blue light output will decrease relative to the other colors of light. This differential color output change will change the color balance of the display and is much more noticeable than a decrease in overall luminance. This can be partially avoided by adjusting colour balance but this may require advanced control circuits and interaction with the user, which is unacceptable for some uses.

In order to delay the problem, manufacturers’ bias the colour balance towards blue so that the display initially has an artificially blue tint, leading to complaints of artificial-looking, over-saturated colors.

  Water Damage

The intrusion of water into displays can damage or destroy the organic materials. Therefore, improved sealing processes are important for practical manufacturing. Water damage may especially limit the longevity of more flexible displays.

 

Outdoor performance

As an emissive display technology, OLEDs are 100% reliant converting electricity to light whereas most LCD displays contain at least some portion of reflective technology and e-ink leads the way in efficiency with ~33% reflectivity of sunlight, enabling the display to be used without any artificial light source.

OLEDs typically produce only around 200 nits of light leading to poor readability in bright ambient light, such as outdoors, whereas displays that use reflective light are able to increase their brightness in the presence of ambient light to help overcome unwanted surface reflections without using any additional power.

  Power Consumption

While an OLED will consume around 40% of the power of an LCD displaying an image which is primarily black, for the majority of images, it will consume 60-80% of the power of an LCD - however it can use over three times as much power to display an image with a white background such as a document or website. This can lead to disappointing real-world battery life in mobile devices.

  Screen Burn-in

Unlike displays with a common light source, the brightness of each OLED pixel fades depending on the content displayed. Combined with the short lifetime the organic dyes, this leads to screen burn-in, worse than was common in the days of CRT-based displays.

ORGANIC THIN-FILM TRANSISTORS 

Organic thin-film transistor (OTFT) technology involves the use of organic semiconducting compounds in electronic components, notably computer displays. Such displays are bright, the colors are vivid, they provide fast response times, and they are easy to read in most ambient lighting environments.

Several factors have motivated engineers to conduct and continue research in organic semiconductor technology. One of these factors is cost. Organic displays are relatively cheap, but until recently, they have proven slow in terms of carrier mobility (the ease with which an atom shares electron s and hole s with other atoms). Slow carrier mobility translates into sluggish response time, which limits the ability of a display to render motion such as is common in animated computer games and, increasingly, on the Web. Researchers at Lucent Technologies and Pennsylvania State University have, however, recently developed a process for growing organic crystals with carrier mobility rivaling that of traditional TFT materials. Further improvements are expected.

Another factor that motivates research in OTFT technology is application diversity. Organic substrates allow for displays to be fabricated on flexible surfaces, rather than on rigid materials as is necessary in traditional TFT displays. A piece of flexible plastic might be coated with OTFT material and made into a display that can be handled like a paper document. Sets of such displays might be bundled, producing magazines or newspapers whose page contents can be varied periodically, or even animated. This has far-reaching ramifications. For example, comic book characters might move around the pages and speak audible words. More likely, such displays will find use in portable computers and communications systems.

  

TOWARDS WOVEN LOGIC FROM OE

The use of organic polymers for electronic functions is mainly motivated by the low-end applications, where low cost rather than advanced performance is a driving force. Materials and processing methods must allow for cheap production. Printing of electronics using inkjets or classical printing methods has considerable potential to deliver this. Another technology that has been around for millennia is weaving using fibres. Integration of electronic functions within fabrics, with production methods fully compatible with textiles, is therefore of current interest, to enhance performance and extend functions of textiles. Standard polymer field-effect transistors require well defined insulator thickness and high voltage, so they have limited suitability for electronic textiles. Here we report a novel approach through the construction of wire electrochemical transistor (WECT) devices, and show that textile monofilaments with 10–100 μm diameters can be coated with continuous thin films of the conducting polythiophene poly(3,4-ethylenedioxythiophene), and used to create micro-scale WECTs on single fibres. We also demonstrate inverters and multiplexers for digital logic. This opens an avenue for three-dimensional polymer micro-electronics, where large-scale circuits can be designed and integrated directly into the three-dimensional structure of woven fibres.

Advantages and Disadvantages of Organic Solar Photovoltaic Market

 Solar power is the technology of obtaining usable energy from the light of the Sun. Solar energy has been used in many traditional technologies for centuries and has come into widespread use where other power supplies are absent, such as in remote locations and in space.Photovoltaics (PV) is the field of technology and research related to the application of solar cells for energy by converting sunlight directly into electricity. Due to the growing demand for clean sources of energy, the manufacturing of solar cells and photovoltaic arrays has expanded dramatically in recent years. 

An organic photovoltaic cell (OPVC) is photovoltaic cell which uses organic electronic materials for light absorption and charge transport. The single layer device structure of OPV cells is comprised of a transparent electrode/organic photosensitive semiconductor/electrode.  

THE FUTURE ROLE OF PRINTING

One of the few positive side effects of recessions is to change the playing field, making it susceptible to disruptive technological developments. One field that is fertile for a major change is electronics and the source of disruption is the application of printing techniques.

Interest in the potential use of printing and specialist coating technologies to produce electronically functional devices is building. Such processes involve laying down specialist conductive or optically active fluids, rather than graphics inks, to make devices such as LEDs and organic solar cells.

IntertechPira estimates the market for new printed electronics - transistors, RFID tags, photovoltaics (PVs) and OLED displays - accounted for some €1.8 billion in sales in 2009 (as the manufacturing value of many high-cost items) and of course the print portion of this market is still small. Some forecasts suggest it may be worth €240 billion by 2025, with companies such as Nanosolar, First Solar and OTB Solar reporting orders in the billions of dollars for their solar cells, which use printing as part of manufacturing. Philips, GE and Konica Minolta among others are developing commercial lighting systems based on OLED technology that involve printing.

  The global electronics industry is looking toward organic and solution processable semiconductor technology to make thin-film, flexible, low-cost electronic devices. Though inorganic semiconductors such as silicon and gallium arsenide dominate electronics - providing superb computational speed and other benefits - they are rigid and brittle, precluding their use where flexibility is required. Printed and organic semiconductors combine the virtues of plastics and semiconductors, providing new electronic properties with scope for easy shaping and manufacture of plastics. 

 

Printing techniquesPrinting offers simpler and cheaper manufacture than conventional

inorganic semiconductors, making it possible to deposit semiconducting polymers and other materials onto a range of substrates, including paper and board.

Print can be used for either rigid or flexible final products. Gravure, flexo and offset are printed in web (roll-to-roll) methods with screen, offset and inkjet as sheetfed.In terms of digital technology, electrophotography is unsuitable as there are significant electrostatic charges, while inkjet is being used for rapid prototyping and then potentially high-volume applications. While there is work into paper- and board-based printed electronics, difficulties in controlling the moisture content means that plastic substrates are more widely used.

The choice of print technology is governed by the substrate properties, film thickness, ink or fluid properties, the format and the cost. Hybrid manufacturing - mixing the print process - is becoming more commonplace to achieve desired characteristics. Indirect gravure pad printing is used in a similar manner but the

resolution is limited. Occasionally transfer methods, where solid layers from a pre-printed carrier are transferred to the substrate, are used.Beside conventional methods new printing processes are being developed, including micro-contact printing and nano-imprint lithography. Here micrometre- and nanometre-sized layers, respectively, are prepared using techniques similar to stamping with soft and rigid forms.

Quality control

Electronic thin-film devices are prepared in printed electronics by printing several functional layers on top of each other. While the resolution of graphics printing (except in some security applications) is determined by visual appearance, to the human eye features below ~20µm cannot be observed. For electronics higher addressing resolution capability and smaller structures are desirable to prepare higher integration densities and boost the functionality of devices. Registration of layers is also critical. Deviation in the application film thickness and absence of defects and holes is important.

As print processes are increasingly used, quality assurance and testing methods are being developed in tandem to ensure high yields of good product. This is particularly important in web-fed roll-to-roll production, where the final components are punched out of a roll later and any defects can be costly. The broad nature of functional fluids to be printed means their transfer characteristics, printability, wetting, adhesion and dissolving need to be considered, as well as the press performance.

  Inkjet

Inkjet deposition could eventually replace some techniques of electronic component manufacture and assembly with a single complete process. Many developers and specialist manufacturers are using inkjet to produce transistors, printed circuits, PVs and displays. In 2008 Konarka announced the first organic solar cell fabrication by inkjet printing. As developers progress, printers and other industries can license materials and processes for making devices.

First Solar and Nanosolar have successfully commercialised production methods using inkjet roll-to-roll methods during 2009. Nanosolar reports printing up to 1,500mm wide on the cell line, at speeds of 40m per minute.

The companies have multi-billion order books for their solar panels - like many printed electronic projects, just a small portion of this is printing value. As these applications take hold, Pira forecasts significant growth in the use of inkjet in the production of electronics, rising from some €62 million in 2008 to a multi-billion market by 2013.

Printing displays

Flexible electroluminescent displays may cover many tens of square metres and emit a range of colours, or be incorporated into small watch faces and instrument displays. HP's Information Surfaces Lab is trying to make flexible electronic displays that can fold like a newspaper or bend around a building. Possible applications range from computer games to product promotions and HP is also working on what it calls 'Dick Tracy's watch' for the military use that might tell soldiers where an enemy is located, or how to clean a machine gun.

  Researchers at MIT demonstrated print deposition of high resolution, patterned, multi-coloured thin films of luminescent colloidal quantum dot (QD)-polymer composites. They claim this results in robust, bright, full-colour displays offering simple, low-cost fabrication and high reliability.

Printing technologies are being employed to produce RFID tags and labels, circuits and memory, OLED displays, PV solar cells and batteries, and new applications including sensors and drug delivery. These devices have significant market potential for added-value products.

Examples that have reached the market include event tickets with RFID to allow visitor entrance and track attendees, board games and trading cards, novelty greeting cards with moving displays and sound, smart packaging, displays and solar power. 

Printed logic

For printed logic and memory applications the first products are RFID tags, though adoption of the technology is slower than many early forecasts. Conventional RFID technology, using silicon chips, has two disadvantages - extended production time and high cost. PolyIC, a joint venture between Siemens and Kurz, in Bavaria, Germany, was set up in 2003 to produce printed electronics. The company supplies printed RFID chips a few square centimetres in area with a thickness of ~1µm.

 The electrodes and the semiconductor layer are just a few hundred nanometres and the distance between the two conductors is less than 50µm. Antennas are positioned at the edge of the chips to transmit and receive radio signals and convey the energy required to operate the unit.

The process of manufacture involves spin-coating then flexo to print the conductors, then coating the foil with the semiconductor and insulator using a type of screen process. Kovio is a start up from the MIT has developed inkjet technology to print RFID tags using silicon-based inks.

There has been a great deal of debate and discussion on the market for printed semiconductors. Some advocates have been proven to be too optimistic, but most commentators are convinced it will take off. Electronic component manufacturers and developers are exploring printing technology to produce new devices or to improve existing ones and increase the efficiency of manufacture. The global electronics industry is looking toward organic semiconductor technology to make thin-film, flexible, low-cost electronic devices and print will be a key part of the manufacturing processes.

  

 

PRESENT, FUTURE DEVELOPMENTS   

Plastic electronics is expected to grow in various applications over the next few years. There are many conferences being held where research papers are being presented and consequently worked upon to implement the plastic electronics in various fields successfully. Once the marketability of plastic electronics has been proved with one successful consumer electronic application, it is inevitable that all the other electronics would very rapidly start developing.   Many companies that were working on small basis in plastic electronics have started to slowly up their production capacity. Leading companies in the field of conventional electronics are currently investing time and money in this technology, realizing the potential for this technology. Many researchers believe that plastic electronics will not only replace silicon and metals in various applications but also play a major role in the invention of new technologies.

 

FUTURE

APPLICATIONS AND FEATURES 

Background Flexible functional materials, such as plastic electronics, have inherent properties that classical silicon semiconductor technologies can never offer. Their flexible form means that they can be used to build displays and panels that can be rolled-up or laminated directly onto surfaces using low cost production facilities. Silicon microchips, on the other hand, are rigid and relatively fragile and so require major investments before production becomes viable. 

Applications   The applications for this technology are limitless - real-time interactive newspapers that can be rolled up like a sheet of paper, surfaces and packaging that respond interactively to consumers, smart clothes with embedded human health and environmental monitors, or ultra low-cost radio frequency identification tags, are just a few examples.

Flexible functional materials will form the basis of the next technology revolution for a new generation of consumer, as well as business products with a lengthy time-to-market. They will evolve a sector estimated by analysts to grow rapidly over the next five years and represent an important economic development opportunity for the region. This is why CPI has led the way in bringing the Plastic Electronics Technology Centre (PETeC) to the North East of England, focusing initially on plastic electronics.    

Features of Plastic Electronics

Plastic electronics offer valuable features that can be commercially exploited to create ambient intelligent environments, enhancing the quality of everyday life and also improving health and well-being.

These features include:

lightweight, flexible, soft and can be shaped emit light and act as semiconductors can be easily structured and integrated into objects

nano/micro surface structures and electronic circuits can be printed directly onto the surface

easier, quicker and cheaper to fabricate require less capital intensive manufacturing facilities very low set-up costs, requiring investment in the order of a few million

pounds, compared to the billions required for a semiconductor facility less stringent constraints on manufacturing environments, compared to

conventional semiconductor plants

These features position plastic electronics as a highly disruptive technology that also offer market opportunities within the next five to ten years. They offer entrepreneurs and companies in the UK major opportunities for innovation and growth.

Consumer Products

Some of today's consumer products are already incorporating plastic electronics. For instance, displays made with arrays of plastic light emitting diodes (LEDs) are currently used in shavers, digital cameras, mobile phones, bright low energy consumption torches and handheld Personal Digital Assistants (PDA) devices. Polymer LEDs also use 50% less energy.

Future applications will include novel products such as real-time electronic newspapers, electronic tags, intelligent interactive packaging, handheld medical diagnostic devices, flexible e-paper for interactive e-books, reports and advertisements, electro-textiles for smart fashion and sportswear and energy in the form of fuel cells, solar cells and batteries.

CONCLUSION

Plastics have become ubiquitous structural materials due to the ease with which they can be processed at low cost into complex shapes. Imagine a world in which metals and semiconductors have similar attributes – that is the world of Plastic Electronics.

This technology has the potential for use in multiple applications including displays, solar energy, solid-state lighting, imaging and sensing, and photonics.

In terms of consumer electronics, this means a wide range of devices can be developed, updated, or revolutionised – from flat screen televisions to e-book readers, from smart windows to printed circuit boards.

Achieving ultimate performance requires a mastery of the chemical and physical structures of materials and interfaces on the molecular-nano-scale. The promise of this technology is founded on the ability to process materials using low temperature coating and printing methods that go beyond those of traditional semiconductor fabrication.