Martin Schadt (LCD TN inventor) 80th birthday cake at LCD’s 50th anniversary at SID DisplayWeek 2018

Posted by Charbax – July 12, 2018

Martin Schadt and Wolfgang Helfrich invented the twisted nematic field effect (TN-effect) in the Central Research Laboratories of F. Hoffmann-La Roche Ltd, in Basel, Switzerland. The resulting patent CH532261 was licensed worldwide to electronics and watch industries and thus initiated a paradigm change towards flat panel field effect LCD.

In the early 1970s, Martin Schadt started to investigate correlations between liquid crystal molecular structures, material properties, electro-optical effects and display performance to obtain criteria for novel, effect-specific liquid crystal materials for TN- and subsequent field-effect applications. His interdisciplinary approach involving physics and chemistry became the basis for modern industrial Liquid Crystal LC-materials research and led to the discovery and production of numerous new functional molecules and new electro-optical effects. In 1970, shortly after the invention of the TN-effect, he developed the first commercial room temperature nematic liquid crystal mixture with positive dielectric anisotropy, used in the displays of the first Japanese digital TN-LCD watches. The pharmaceutical company Roche established itself as a major supplier of liquid crystal materials for the emerging LCD-industry.

Apart from his pioneering work on the TN-effect (i.e.e twisted nematic field effect), novel liquid crystal materials, organic semiconductors and biophysics, he invented or co-invented the following effects and technologies:

- first organic light-emitting diode (OLED) (1969 as post-doc at Canada's NRC; US patent 3,621,321),
- Kerr effect in LCs (1972),
- field-induced guest-host color switching (1979),
- dual frequency addressing and materials (1982),
- optical mode interference (OMI)-effect (1987,)
- deformed helix ferroelectric (DHF)- and short pitch bi-stable ferroelectric (SBF)-effect (1989, 1990),
- linearly photo-polymerisation (LPP)-technology (1991).

As principal inventor and head of Roche LC research he promoted the development of LPP-Photo-alignment into manufacturing (1992–2002). As a key technology it enables contact free alignment and photo-patterning of monomeric and polymeric liquid crystals by optical means instead of mechanically. This has opened up novel display configurations as well as a wide range of new optical thin-film elements on single substrates, such as LC-interference color filters, optical retarders, cholesteric optical filters, wide-view films to enhance the field of view of LCDs, novel optical security elements for document and brand protection, stereo-polarizers as well as nano-and micro-corrugated optical polymer thin-film elements enabling polymeric antireflective and directional light scattering coatings.

The molecular design approach of Martin Schadt and his team has led to the discovery, patenting and production of the following commercially important liquid crystal classes: alkyl cyano Schiff'bases and esters (1971), phenyl-pyrimidines (1977), alkenyl liquid crystals which have become key for all state-of-the-art high-information content LCDs (1985–1995), numerous halogenated liquid crystals (1989–1995) as well as the first strongly non-linear optical (NLO)-ferroelectric liquid crystals (1992).

Until 1994 Martin Schadt was the head of the Liquid Crystal Research division of F. Hoffmann-La Roche Ltd. As a spin-off from Hoffmann-La Roche in 1994 he founded the interdisciplinary research and development company ROLIC Ltd. From 1994 until his retirement from the operating business in October 2002 Martin Schadt was CEO of ROLIC Ltd. and delegate of the board of directors. He retired from ROLIC in 2005 and is now active as a scientific advisor to various research groups and governmental agencies.

Martin Schadt has published 167 scientific papers, co-authored four books and holds 116 patents, and previously received the Roche Research and Development Prize and Karl Ferdinand Braun Prize of the American Society for Information Display (SID); highest recognition Award of SID.