center for organic materials and electronic devices dresden

Transcription

1 F R A U N H O F E R I N S T I T U T e F o R P h o t o n i c M i c r o S y s t e m s I P M S center for organic materials and electronic devices dresden

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3 Dr. Christian May Head of Business Unit Prof. Dr. Karl Leo Director Dear Reader, Organic semiconductors are the technological basis for a multitude of innovative products, such as organic light emitting diodes, solar cells, and many other applications. However, the establishment of a powerful European industry for these products can only succeed if industry and research institutions not only work together on technology and design, but also co-operate on on-site manufacturing. The Fraunhofer-Gesellschaft has recognized this and established the Center for Organic Materials and Electronic Devices Dresden (COMEDD) the leading center for research, development and pilot production of organic devices in Europe. Over the past years Dresden has evolved into a strong cluster of companies and institutes working on organic materials and systems. In order to transfer these developments into production, further improvements in the production process and the establishment as well as the testing of initial pilot-production lines are necessary. That is why COMEDD was founded at the Fraunhofer Institute for Photonic Microsystems IPMS. COMEDD combines research and development activities for the production, integration and technology of organic devices. The mission of COMEDD is research geared specifically toward customer applications, the development and pilot production of unique device concepts, as well as production methods for vacuum deposited organic materials. The goal of the Center is, specifically, the creation of a production-oriented and pan-european leading research and development center for organic semiconductors, focusing on organic light-emitting diodes and vacuum technology. These activities are supported by the Fraunhofer-Gesellschaft, the Free-State of Saxony, the Federal Government of Germany, as well as by the EU, with additional investments of 25 million Euros for its infrastructure. We invite you as our potential partner and customer to join our mission and succeed with us using our unique infrastructure and competencies. 01

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5 technological basics Organic light emitting diodes consist of stacks of organic layers (several 100 nm thick) sandwiched between a cathode and an anode. Typically, the substrate is glass, coated with a transparent conductive oxide layer, which is the anode, followed by the organic stack, which consists of hole transport (conductive) and electron transport (emissive) layers, followed by the inorganic cathode. Organic solar cells exhibit a very similar stack layer architecture to OLEDs. The emitter material in the organic stack is replaced by an absorber material. In organic semiconductor technology, we differentiate between two separate material groups: organic oligomers, with low molecular weight called small molecules, and long polymer chains on the other hand. The deposition of small molecule layers is carried out by vacuum thermal evaporation. The polymer layers are deposited using wet processes like spin coating or ink-jet printing. Small molecule OLEDs attain the highest efficiency by using phosphorescent emitters in combination with doped transport layers. Based upon these advanced concepts, green OLEDs are actually the most highly efficient solid-state light source available. It is also important to note that the lifespan of OLEDs has increased dramatically over the past few years. Several hundred thousand hours at 1000 cd / m² have been attained for selected colors. Key advantages of organic luminescence are the chemical variability of organic light-emitting diodes, which allows for virtually any color, including white, as well as the thin film system, which allows for large-area and low-cost deposition, and the possibility to employ thin and even flexible substrates to create a unique class of lighting and display applications. A white OLED is usually required for an illumination light source or backlight. One approach is to employ a multi-layer structure with simultaneous emission of light from two or more separate emitting layers in different emission colors. This results in white light. Due to extensive work, the energy efficiency of white OLED devices will reach the quality level required for a broad market acceptance of white OLED lighting. Light Emission Transport layer Emitting layer Transport layer 02 I 03

6 1 2 Benefits of OLEDs The advantages of OLED technology are obvious. OLEDs are bright, thin, and efficient, and they can be deposited at low cost on various substrate materials including glass, plastic, or metal foils as well as silicon. The challenge is to produce OLEDs that can compete with existing light sources in efficiency, stability, color quality, and operational lifespan. OLEDs are self-luminous area emitters. Organic light-emitting diodes are based upon a self-luminating display technology that utilizes substances which emit red, green, blue, white, or differently colored light. Unlike LCDs, there are neither backlights nor chemical shutters that have to open and close. Instead, each pixel illuminates like a light bulb. As with inorganic light-emitting diodes (LEDs), OLEDs require a low drive voltage to produce bright visible light. However, unlike point-source LEDs, which are of crystalline origin, layer-based OLEDs are area emitters. Because OLEDs produce their own light, they appear extraordinarily bright, display unusually high contrast, and are easy to see at almost any angle. OLEDs are thin and light weight OLEDs can be made very thin and lightweight because they are self-luminous and do not require additional components such as backlights or diffusers. The advantage of OLEDs, free from the added bulk and weight of backlighting, is particularly important for compact devices. At the same time, it is essential for general lighting applications where form is a critical factor in product design. The thickness of an OLED layer stack is several 100 nm, and the thickness of a panel for lighting applications on a glass substrate can be less than 1 mm. These characteristics make it possible for OLEDs to be used for lighting design in constricted spaces, and they could allow OLED lighting to be placed directly on ceilings rather than to hang from them. 1 The manufacturer s logo is placed in the centre of nearly every car s steering wheel. The German OLED research association CARO which stands for Car OLED presents innovations in OLED device integration technology for automotive applications. 2 Normally, the implementation of touch screen features requires additional touch layers on the top of the devices. The newly developed interactive touchcontrolled OLED requires no additional hardware because the OLED itself is used to read out the touch signal. As an OLED is a cold light source, touch control is a safe operation. 04

7 3 4 Due to the minimum thickness of both the OLED layer and the electrodes, the OLED device can be transparent in its off-state. Transparency can reach 60% within the range of 400 to 800 nm wavelength. The light generation ratio for both directions can be varied from between 50% / 50% to 20% / 80%, depending on the OLED cavity design. Because OLEDs can be transparent, exciting new OLED lamp designs are possible. OLEDs are flexible. Another great benefit of OLED technology is its manufacturing process. The technology requires very few materials and a limited number of process steps, which makes OLEDs potentially inexpensive to manufacture. OLEDs are also manufactured close to room temperature, which makes it possible to apply OLEDs onto almost any substrate, including plastic or metal films. That is why new applications like roll-up displays are possible, and why OLEDs can be integrated onto various application-specific materials, such as processed silicon wafers. This opens up a variety of completely new applications, in which different sensor devices (e.g. photo detectors) are integrated into CMOS circuit technology. In such a case, the light emitter can be placed above the CMOS electronics without using up much-needed chip space. OLEDs are very power efficient. OLEDs have an intrinsic advantage that they only consume power while they are emitting light. For example, a black OLED pixel consumes no power. This is especially important for battery-operated devices such as cell phones. Low power consumption and operating voltage, combined with maximized battery life and minimized heat and electrical interference in electronic devices make OLEDs very economical. 3 Due to their thin, lightweight and potentially flexible architecture, organic solar modules are particularly suitable for mobile applications. 4 Micro-displays, i.e. displays with state-of-theart pixel count but with significantly decreased geometrical size, have found their way into consumer electronics. Micro-displays based on Organic Light Emitting Diodes (OLED) are considered a very promising future technology for multimedia applications such as video and data displays. The breakthrough is expected to happen within the next couple of years. 05

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9 services at a glance W i t h i n t h e a r e a s o f a p p l i c a t i o n OLED Lighting and Signage Organic Micro-Opto-Electro-Mechanical Systems Organic Photovoltaics w e o f f e r Consulting services Feasibility tests Simulations Device and system development Material tests Complete process development Prototypes and demonstrators Characterization & Test Pilot-Fabrication 06 I 07

10 1 2 core competencies R&D of Fabrication Technologies The manufacturing processes currently available for organic semiconductor devices are not suited for mass markets. New manufacturing concepts and procedures are needed in order to produce unique, new devices at marketable costs. COMEDD offers its customers the development and testing of new manufacturing concepts in an industrial-like environment, which includes the characterization of individual process steps and the development of complete production processes. 1 First OLED sample from the Gen2 process line: The new pilot line allows for customized layouts on 370 mm x 470 mm substrates. The facility is equipped to allow for the development of manufacturing technologies for both small substrate sizes as well as for larger dimensions for production evaluation. For the production of substrates for large area OLEDs and solar cells, COMEDD can provide the development of photolithography-free processes based on screen printing and laser ablation. These manufacturing processes make the manufacture of substrates based on innovative transparent conductive oxide materials (TCO) possible. Fraunhofer IPMS has experience in testing customized alternative TCO layers in terms of suitability for organic light emitting diodes and solar cells. The development of this procedure for transparent, non-transparent, rigid as well as flexible substrates is possible. For the deposition of organic and functional layers, COMEDD utilizes the latest point and line sources for thermal evaporation and organic vapor phase deposition (OVPD). Both the evaporation of metals and sputtering for TCO and metals are available for testing innovative electrode materials. It is possible to apply this procedure to glass substrates, metal substrates as well as transparent and flexible plastic substrates. Unique to COMEDD is the option to evaluate each of the various deposition processes without interrupting the vacuum process. This makes it possible to evaluate materials or components parallel to various manufacturing processes, and to determine their impact on product efficiency and lifespan. This includes the identification of process stability based upon statistical process analysis. 2 Funded by the Federal Ministry of Education and Research, the Rollex project (roll-to-roll production of highly efficient light emitting diodes on flexible substrates) began in The goal of the cooperating partners is the development of new technology to produce highly efficient and low priced OLEDs in order to provide a sustainable and affordable alternative to the conventional bulb and fluorescent lamp. 08

11 3 R&D of Integration Technologies and Product Development COMEDD develops close-to-market products for its clients. The development of process technologies includes the qualification of integration processes for pilot serial production and includes the manufacture of prototypes and demonstrators. With COMEDD, Fraunhofer IPMS is in a position to offer complete solutions from one source, ranging from specification to pilot production and including component development, system development and integration. As a result, COMEDD offers extremely short development timelines and a shortened time to market. Because OLEDs are manufactured at close-to-room temperature, it is possible to apply them to almost any substrate material including not only glass but also silicon, metal or plastic films. COMEDD provides the necessary expertise in terms of the impact of critical parameters, especially oxygen penetration, electrode layer roughness or work function as well as modern equipment for the integration of all of these substrate materials. Successful tests on glass, silicon, metal and polymer substrates have already been carried out, including the integration of OLEDs in printed circuit boards. Optical simulation, accounting for thermal conditions and encapsulation effects of the devices, is an important tool for obtaining optimum efficiency, especially on non-transparent substrates. The encapsulation can also include the integration of micro-optical elements. 3D simulation capacity is available for the simulation of such elements. 3 The core components of the fabrication lines are the vacuum deposition tools for depositing active organic semiconducting layers (small molecules). For the fabrication of organic light emitting diodes and solar cells on substrates with a size of 370 x 470 mm², a plant concept was realized, which allows for the use of either vacuum evaporation or the OVPD method, or a combination of both. The timing cycle of 3 minutes makes this pilot fabrication line the system with the highest volume in Europe. Pilot-Fabrication COMEDD offers the transfer of technology and components within an in-house pilot production line. This allows for the speedy implementation of new device concepts into production and evaluation of manufacturing processes within an industry-related environment. Fraunhofer IPMS internal testing equipment and procedures are utilized for the qualification of the devices prior to pilot-fabrication, and specifically for processes in organic devices. An extensive network of partners for specific test procedures (such as temperature shock or environmental testing) is also available. For pilot production, Fraunhofer IPMS has established a two-shift operation with an effective manufacturing production system as well as continuous quality control of all materials, equipment and processes. Fraunhofer IPMS is ISO 9001:2000 certified for the research, development and fabrication of photonic micro-systems including semiconductor and micro-system processes, as well as integrated actuators and sensor technologies. 09

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13 Lighting and Signage Currently, organic light-emitting diodes (OLEDs) are used to make beautiful and efficient displays for small- screen devices such as cell phones, digital cameras, and MP3 players. However, OLEDs also promise to be one of the key technologies of the future in regard to lighting and signage, as well as for optical sensor applications. Incandescent and fluorescent lamps are light sources produced with sophisticated technology and functionality, which dominate today s general lighting market. Incandescent light bulbs emit 15 lumens per watt. Fluorescent lights output roughly 60 lumens of light per watt, but they have drawbacks: they produce light with limited color rendering quality, lack longevity, and contain environmentally damaging substances such as mercury. In comparison, white OLEDs emit a white light that is brighter, more uniform and potentially more energy efficient than that emitted by fluorescent lights. White OLEDs also exhibit the same true-color qualities of incandescent lighting. Because OLEDs can be made in large sheets, they could replace the fluorescent track lighting currently used in homes and buildings. Over the past decade, LEDs based on semiconductors have reached a maturity, well beyond their originally intended functionality and fields of application (indicator, status, and signal lights, as well as display technology). Lighting based on organic light-emitting diodes is still in the development phase compared to LEDs, but OLEDs are already showing a large potential to become the light source of the future, and will complement LEDs as an important solid-state area light source: An enormous growth market. With flexible or transparent OLEDs, completely new lighting solutions are possible. Flat, white lighting device as an example for emotional lighting. At a size of 200 x 200 mm², it demonstrates the leading position of Fraunhofer IPMS in OLED manufacturing worldwide. Today, a large portion of the electricity produced goes toward lighting of buildings. Employing a highly efficient form of OLED lighting could significantly reduce lighting energy costs. OLEDs as the main source for complete lighting solutions will not simply be a substitute for existing lighting technologies. They will also generate new applications, owing to the unique properties of large area diffuse lighting with adjustable colors. 10 I 11

14 1 2 OLED-On-cmos For the first time, OLEDs make it possible to integrate highly efficient light sources with photo detectors on a CMOS backplane. Fully integrated optoelectronic applications based on silicon can now be realized. Personalized mobile information systems and devices, such as cell phones / smartphones, PDAs, etc. have become an indispensable part of everyday life. The natural limitations of human vision and direct view display technologies make for multitudes of new types of display technology to be developed, which open up innovative product design opportunities. Micro-displays based upon OLED-on-CMOS are especially of interest for camera viewfinders, overhead projectors, rear projection screens, and the emerging market of wearable displays. For instance, one can create a bidirectional micro-display with micro-scale optical emitters and receivers on the same chip in an array type of organization, i.e. a device that displays and captures images at the same time. It presents information to the user and at the same time optically recognizes user interaction. The user perceives his or her environment as normal, but additional information is presented via an advanced type of glass which bear bi-directional micro-displays (Augmented Reality, AR). This visual information can be deliberately and unconsciously adapted to the context of the system s operation, and the user can interact without the need for hands or speech. Simple eye-movement or expression is sufficient. Organic light emitting diode technology is the first viable opportunity to integrate highly efficient light sources onto CMOS substrates. The possibilities for potential applications are endless: Light barriers, flow sensors or fingerprint sensors are only a few examples of how OLEDs can be applied to sensor applications. 1 The Fraunhofer IPMS microdisplay the result of the BMBF funded project ZOOM has attracted worldwide attention. A subsequent project called ISEMO (also funded by BMBF) was started in late The OLED microdisplay here is projecting a controlled pattern onto an object surface, while the embedded camera observes the distortion of the light pattern caused by the object s topography. The resulting image pattern is used to calculate the object s surface shape. It is thus possible to produce miniaturized, integratable deflectometric sensors for the characterization of surfaces (finish and form). 2 Flux sensor with OLED light source integrated on a CMOS-sensor chip. 12

15 organic photovoltaics One of the most urgent challenges facing mankind is replacing fossil energy sources. Environmentally friendly energy sources are needed. Solar power can help to solve this problem, but even its energy has to be converted into electricity. One approach is the use of organic solar cells. Up until now, organic solar cells have been mainly investigated and produced only on a laboratory scale and on very small areas, with insufficient efficiency and stability. However, the existing drawbacks, such as efficiency and lifespan can be solved by using controlled complex material architecture, employing new material and synthesis approaches and concepts on the one hand, and the use of metal, metalized or polymer foils to make solar modules flexible and producible, along with processes suitable for high-volume manufacturing on the other. The resulting modules will be low-cost, lightweight and flexible both in shape and form, as well as in color and design. Due to low-cost materials and close-to-room temperature manufacturing processes, a short energy payback time is to be expected. A novel tandem cell concept will be used to achieve improved efficiency. Further improvements in efficiency are expected due to the development of new light absorbing organic materials which will cover a larger wavelength range. 3 Organic solar cells can provide features which competing technologies do not offer. Solar cells with various colors and shapes as well as transparent modules are possible. 4 Recently, a power conversion efficiency of 6.07% for a tandem solar cell using Heliatek s proprietary tandem cell technology was certified. This cell, with an active area of 2 cm², already possesses many of the essential characteristics of a large solar module. It was developed from the results of the project OPEG, sponsored by BMBF were Heliatek and IPMS working at partners. Later on these cells will be available as flexible modules. 13

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17 resources and equipment Pilot line OLED / OSC on rigid substrates substrates 370 x 470 mm² Laser Ablation 3D Micromac Ultrasonic Pre-Clean system UCM-4 UCM Double-sided single-panel cleaning processor SSEC MODEL 3402 SSEC Automatic screen and stencil printer X4 Prof EKRA Thermal treatment Carbolite Deposition by thermal evaporation Sunicel 400 plus Sunic System Deposition by OVPD Aixtron Encapsulation system Vision Technology Pretest MRB Automation Scriber AI PO LI Microscopes Eclipse L300 Nikon Pilot line OLED on CMOS wafer 150 mm and 200 mm Cleaning / Etching Wet bench Arias, Semitool Clean oven CLO2AH Koyo Thermo Systems Deposition by thermal evaporation Sunicel 200 plus Sunic System Semi-automated wafer bonding system EVG510 and IQ-ALIGNER 200 TN EVG Research line Roll-to-Roll metal strips 300 mm width Deposition by thermal evaporation Rollex 300 Von Ardenne Rewinding and inspection system Spanntec Prototype line / Further systems Material test deposition system BESTEC Vertical inline deposition system VES400/13 Applied Materials Auto drive stencil printer S70 Mechatronic Engineering Modular vacuum sublimation unit DSU-1.0 CreaPhys Climatic chamber Vötsch Measurement / Characterization Microscopes Eclipse L200 Nikon Profilometer Alphastep IQ KLA Tencor Particle scanner Surfscan 6200 KLA Tencor Display test system DMS 401 Autronic Melchers Display test system CAS 140B Instrument Systems Video photometer PR 905 Photo Research IR camera Variotherm Head II Infratest Solar cell test system Aescusoft 14 I 15

18 o r g a n i c e l e c t r o n i c s s a x o n y The state of Saxony and particularly the region of Dresden host Europe s largest cluster for organic semiconductor R&D and manufacturing. More than 15 companies and 8 research institutes with over 750 employees are active in this exciting and quickly growing new technology covering the whole value chain starting at universal fundamental research up to high end technological products. CREAPHYS The Organic Electronics Saxony e.v. offers its members and all interested partners a competence network and supports each member individually. 16

19 e d i t o r i a l n o t e s F r a u n h o f e r I n s t i t u t e f o r P h o t o n i c M i c r o s y s t e m s, Address: Contact: Telephone: Fax: Internet: Maria-Reiche-Straße 2, Dresden Ines Schedwill +49 (0) (0) ines.schedwill@ipms.fraunhofer.de Copyrights Text Proofreading Layout: Print All rights reserved. Reproduction requires the permission of the Director of the Institute. Fraunhofer IPMS Tara Kneitz, Dresden Fraunhofer-Gesellschaft MEDIENHAUS Lißner OHG, Dresden Photos Fraunhofer-Gesellschaft; Photographie Jürgen Lösel; Thomas Ernsting; Quantum Design; Heliatek GmbH (page 13-4) Optrex Europe GmbH (page 4-1)

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