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| February 19, 2014 |
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Mitsubishi Chemical-UCSB Tie-up's Organic Thin Film Transistors
Set New World Standard for Carrier Mobility with Semiconducting Polymers
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Mitsubishi Chemical Corporation
Mitsubishi Chemical Corporation (MCC; Head office: Chiyoda-ku, Tokyo, President: Hiroaki Ishizuka) and the University of California, Santa Barbara (UCSB; California, USA) formed a comprehensive R&D alliance and established the Mitsubishi Chemical Center for Advanced Materials (MC-CAM) at UCSB in 2001. Since then, in the field of advanced functional materials, MC-CAM has focused on making breakthroughs in novel materials, devices, and process and analysis technologies. UCSB recently announced that the collaborative team at MC-CAM reached the world's highest levels of carrier mobility* for organic thin film transistors (OTFTs) made from semiconducting polymers, and the results were published in Advanced Materials (http://engineering.ucsb.edu/news/753).
Thin film transistors (TFTs) are used mainly in LCDs as switches to turn individual pixels on or off. Silicon (poly-crystalline and amorphous) is widely used for TFT devices today. In general, poly-crystalline silicon TFT has higher carrier mobility but lower uniformity due to its poly-crystalline nature, and is difficult to be produced in larger areas because of the requisite fabrication process. On the other hand, amorphous silicon TFT can be processed at around 400 degrees C, a lower temperature than the poly-crystalline type, and is capable of large-area fabrication due to its high uniformity. But the carrier mobility of amorphous silicon TFT is not high enough for use in next-generation displays such as OLED displays (which requires mobility of 10 cm2/Vs or higher). At the same time, both poly-crystalline and amorphous silicon TFTs need high temperature processes, which makes it difficult to fabricate on polymer surfaces for flexible devices.
Compared to silicon TFT, OTFT can be fabricated into flexible devices, and in general, the materials are suitable for printing processes at much lower temperature. Thus, OTFT is believed to have the potential to be used in large-area, low-cost flexible devices. But conventional semiconducting organic materials have mobilities less than 10 cm2/Vs, which is insufficient for practical use.
MC-CAM researchers recently achieved a carrier mobility of 23.7 cm2/Vs, which is among the world’s highest. It was obtained through the efforts of a collaborative team at MC-CAM using newly developed polymers from the group of Prof. Guillermo Bazan, device fabrication technology from Prof. Alan Heeger's group, and characterizations by Prof. Edward Kramer's and Prof. Thuc-Quyen Nguyen's groups. Their combined efforts mark a huge step toward practical use of OTFTs.
MCC will proceed with further development of this technology at Mitsubishi Chemical Group Science and Technology Research Center, Inc. (Head office: Aoba-ku, Yokohama-shi; President: Tomoyuki Mori) in cooperation with MC-CAM.
*Carrier mobility gauges how easily charged carriers (electrons, holes) can move through semiconductors. Larger numbers will enable faster switching speed in individual pixels, leading to the goal of brighter high-definition displays.
For further information, please contact:
Public Relations and Investor Relations Office
Mitsubishi Chemical Holdings Corporation
Tel: [+81] (0)3-6748-7140
About MC-CAM
MCC and UCSB established the Mitsubishi Chemical Center for Advanced Materials (MC-CAM; Director: Prof. Glenn Fredrickson (CTO-to-be of Mitsubishi Chemical Holdings Corporation as of April 1, 2014)) in 2001 on the UCSB campus. In cooperation with UCSB's College of Engineering and Material Research Laboratory, MC-CAM has focused on making breakthroughs in novel materials, devices, and process and analysis technologies in the field of advanced functional materials. Research on high carrier mobility in semiconducting polymers and related device fabrication processes started in September 2010 as one of MC-CAM's principal research themes. In the MC-CAM program, MCC researchers participate as industry partners, and collaborate closely with UCSB researchers.
URL: http://www.mc-cam.ucsb.edu/
About the MC-CAM OTFT research team
Prof. Alan J. Heeger
His current research interests lie in the area of transport in semiconducting polymers and light emission from semiconducting polymers. He won the 2000 Nobel Prize in chemistry (discovery and development of electrically conducting polymers). His research group developed device fabrication method to enable the high mobility.
Prof. Guillermo C. Bazan
His current research activities are focused on the molecular design and synthesis of innovative, functional materials. His research group developed the novel polymer.
Prof. Edward J. Kramer
His current research activities are focused on polymer interfaces using a variety of depth profiling and microscopic imaging methods.
Prof. Thuc-Quyen Nguyen
Her research focuses on understanding the photophysics and electronic properties of novel organic and metal-organic hybrid materials.
Prof. Kramer's and Prof. Nguyen's groups characterized the surface structure of the newly developed devices.
URL: http://www.mc-cam.ucsb.edu/people/faculty/
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