Friday, October 31, 2014
Tuesday, October 21, 2014
Distinguished Seminar Series: "Field-Effect Liquid Crystal Displays, LC-Materials & Optical Alignment of LCs" by Martin Schadt 11.14.14/12:00-1:00pm/ CREOL 103
Distinguished Seminar Series: "Field-Effect Liquid Crystal Displays, LC-Materials & Optical Alignment of LCs" by Martin Schadt
Friday, November 14, 2014 12:00 PM to 1:00 PM
CREOL Room 103
CREOL Room 103
Dr. Martin Schadt
MS High-Tech Consulting, CH-4411 Seltisberg, Switzerland
Since the invention of the twisted nematic (TN) field-effect in 1970, the nematic liquid crystal display technology which is based on electric field-effects has made remarkable progress. Field-effects are characterized by polarization sensitive macroscopic molecular liquid crystal configurations with electrically tunable optical appearance.
The unique electro-optical building block concept of field-effect LCDs enables the integration and individual optimization of anisotropic optical thin-films and silicon electronics in LCDs. The remarkable progress made over the past 45 years, renders today virtually all applications of the communication between man and machine possible. They range from reflective LCDs with “zero power” consumption, such as digital watch LCDs, or remotely controlled electronic price tags in Shopping centers, to iPhones and large size, ultra-high resolution 4k television LCDs. Since the beginnings in 1970 this development has been spurred by interdisciplinary R&D between physics, material sciences, synthetic chemistry, semiconductor electronics, and engineering. It includes TN-LCDs (1970), super-twisted nematic (STN)-LCDs (1980s), thin-film transistor (TFT)-addressed TN-LCDs for computer monitors in the early 1990s and beyond, and multi-domain LCD configurations. The latter became possible in the late 1990s either by electric fringe-field electrode geometries, or by photo-alignment/patterning of LC molecules. Further enhanced contrast, large angles of view and shorter response times were the result. Moreover, spin-offs into potential future types of field-effect LCDs, such as polymer stabilized blue phase LCDs and ferroelectric LCDs became possible.
This development is reviewed with examples of the multidisciplinary R&D of the author and collaborators on electro-optical field-effects, liquid crystal materials and polarized optical alignment and alignment patterning of monomeric and polymeric liquid crystal molecules in LCDs and optical thin-films based on liquid crystal polymers.
Dr. Martin Schadt was born on 16th August 1938 in Liestal, Switzerland. After having gained practical experience as electrician Martin Schadt majored in experimental physics at the University of Basel, Switzerland, where he received his PhD in 1967. He was granted a two year post-doctoral fellowship at the National Research Council, Ottawa, Canada, where he continued his research on the electronic and optical properties of organic semiconductors. In 1969 he and D.F Williams patented the first solid state, organic light emitting display (OLED). Dr. Schadt’s first professional association was with the watch company Omega, where he investigated atomic beam standards. In 1970 he joined the Central Research Laboratories of F. Hoffmann-La Roche Ltd., Basel. Except for two years in biophysics, his research focused on the development of electro-optical field-effects based on liquid crystals and on liquid crystal materials. 1970 Dr. Helfrich and Dr. Schadt invented the twisted nematic (TN)-effect at F. Hoffmann-La Roche. The Roche TN-field-effect patent was granted in 20 countries and was licensed world-wide to the emerging field-effect LCD industry by Roche. The invention initiated a paradigm change towards flat panel field-effect liquid crystal displays (LCDs) enabling today’s LCD industry. The search for correlations between molecular structures, material properties and display performance, which Dr. Schadt started in the early 1970s, enabled the development of new liquid crystals for TN- and subsequent field-effect applications. As a consequence the pharmaceutical company Roche established itself as a major liquid crystal materials supplier for the emerging LCD-industry. Apart from his pioneering work on OLEDs, the TN-effect and liquid crystal materials, Dr. Schadt and collaborators invented the linear photo-polymerization (LPP) technology in 1991 enabling alignment of liquid crystal molecules by light instead of mechanically. This opened up novel LCD configurations and LCD operating modes, as well as numerous anisotropic optical polymer thin-films.
Until 1994 Dr. Schadt headed the Liquid Crystal Research Division of Roche. Based on its photo-alignment technology the Division was turned in 1994 into the spin-off company ROLIC Ltd, an interdisciplinary Research and Development Company which Dr. Schadt built-up and headed as CEO and delegate of the Board of Directors until his retirement from the operating business in October 2002. He is now active as a scientific advisor to research organisations and continues research in collaboration with partner companies as an independent inventor. He is inventor or co-inventor of 166 patent families filed in Europe (EP) and holds more than 119 US patents. He has published 191 papers in leading scientific journals, including chapters in 6 books. Dr. Schadt became a Fellow of the Society Information Display (SID) in 1992 and a Fellow of the European Academy of Sciences in 2011. He is inventor or co-inventor of 166 patent families filed in Europe (EP) and holds more than 119 US patents. He has published 193 scientific papers in leading scientific journals, has given more than 150 lectures and contributed to 6 books. He has received the following Awards: the Roche Research and Development Award (1987), a Special Recognition Award and a Best SID Paper Award (1987), the SID Karl Ferdinand Braun Award (1992). Together with W. Helfrich, he received the Aachener und Münchener Preis für Technik und angewandte Naturwissenschaften (1994) and the Robert-Wichard-Pohl Prize of the German Physical Society (1996). Together with W. Helfrich and James Fergason, he received the IEEE Jun-ichi Nishizawa Medal (2008). In 2009 he received the Eduard Rhein Technoloy Prize. The G.W. Gray Medal of the British Liquid Crystal Society and the Blaise Pascal Medal for Material Sciences of the European Academy of Sciences (2010). The Frederiks Medal, highest recognition award of the Russian Liquid Crystal Society (2011). The Charles Stark Draper Prize of the US National Academy of Sciences (known as the “Engineering Nobel Prize”) together with G. Heilmeier, W. Helfrich and P. Brody (2012). European Inventor Award 2013 for Lifetime Achievement (2013). Fellow of US National Academy of Inventors NAI (2013). Honorary Prof. of Sichuan University, Chengdu (2013). Honorary Prof. of Nanjing University, Nanjing (2013).
For additional information:
Dr. Shin-Tson Wu
Monday, October 6, 2014
TODAY!! Seminar: "Semiconductor Nanomaterials for Information and Energy Technologies" by Dr. Yajie Dong 10.6.14/ 11:00-am-12:00pm/ CREOL 103
Seminar: "Semiconductor Nanomaterials for Information and Energy Technologies" by Dr. Yajie Dong
Monday, October 6, 2014 11:00 AM to 12:00 PM
CREOL Room 103
CREOL Room 103
Low dimensional nanomaterials (1 D nanowires and 0 D quantum dots) represent important nanoscale building blocks with substantial potential for exploring new device concepts and materials for nanoelectronics, optoelectronics and energy technology applications. Three examples will be presented. First, I will discuss my discovery of unique rectified silver/amorphous silicon/crystalline silicon (Ag/a-Si/c-Si) crossbar resistive random access memory (RRAM) effect in c-Si/a-Si core/shell nanowires and provide a comprehensive comparison between nanowire based and planar silicon based Ag/a-Si/c-Si RRAMs. The history of how this accidental nanowire based discovery solved a decades-long sneak current problem in RRAM field and eventually evolved into a game changing mainstream flash memory successor, Crossbar Memory, will be presented. Then I will report the experimental realization of high efficiency single coaxial group III-nitride heterostructured nanowire photovoltaic devices and light emitting devices. Meanwhile, a universal van der Waals epitaxial growth strategy for compound semiconductor nanowire arrays will be discussed. The vision of how the combination of nanowire array growth and heterostructured nanowire devices could possibly change the substrate limited status of III-Nitride research fields will be outlined. Lastly, I will present how quantum dots materials innovation and novel device structure design/processing helped resolve one long standing issue for organic based light emitting devices, the efficiency roll off at high driving current density. As a result, record breaking ultrabright, highly efficient, low roll off inverted red quantum dot light emitting devices (QLEDs) have been achieved (165,000Cd/m2 at <6v attack="" be="" discussed="" driving="" end.="" in="" instability="" issue="" long="" of="" only="" p="" qleds="" remaining="" strategies="" term="" the="" to="" voltage="" will="">
Dean & Director, Professor of Optics
Dr. Yajie Dong is an assistant professor in NanoScience Technology Center of University of Central Florida. He got his BS and MS degrees in Chemistry from Tsinghua University of Beijing, China. In 2010, he received his PhD degree from Prof. Charles Lieber's group at Chemistry and Chemical Biology Department of Harvard University. From 2010 to 2012, he was a postdoctoral associate working with Professors Yet-Ming Chiang and W. Craig Carter in the department of Material Science and Engineering at the Massachusetts Institute of Technology. Before joining NSTC of UCF in August 2014, he worked as a Senior Scientist for QD Vision Inc., a Nanotech Startup based on research of Professors Moungi Bawendi and Vladimir Bulovic’s groups at MIT and located in Lexington, MA. He is broadly interested in materials challenges in nanoelectronics, optoelectronics and energy technologies, particularly in nanoscale nonvolatile resistive switches for information processing and storage, compound semiconductor nanowires or quantum dots based high efficiency energy conversion (LED and PV) devices and new battery materials and architectures for large scale energy storage.
For additional information:Dr. Bahaa Saleh
Dean & Director, Professor of Optics