FlexiOM™: The best OTFT materials for OLCD

Mike Banach, Technical Director

February 05, 2020

The use of high-performance, high quality organic materials has always been paramount to the development of OTFT-based devices.

Last November we were delighted to announce that FlexEnable has acquired the best-in-class OTFT materials portfolio from Merck. Coupling this portfolio with our world leading flexible OLCD process technology is not only a great strategic fit for our business, but also brings benefits to our customers – we can now supply tested and proven materials to display manufacturers adopting our technology platform which is compatible with existing TFT LCD lines.

Flexible LCDs enabled by FlexiOM™

Close-up of OLCD with 10mm bend radiusUp until now LCDs have exclusively used active matrix backplanes on glass with hard ceramic-based materials as the basis for the fundamental transistor technology. To enable flexible LCDs on plastic FlexEnable has pioneered an alternative manufacturing approach which replaces the hard ceramic materials with soft, flexible organic materials. We have called this technology Organic LCD (OLCD). Over the last several years our display innovations were supported by Merck who developed the semiconductors and dielectrics which helped enable manufacturing on low-cost non-birefringent substrates. These OTFT materials are now available from FlexEnable as ready-optimised formulations for use in existing display factories.

FlexiOM™ performance

An active matrix backplane for OLCD employs at least three FlexiOM™ layers. The first is FE-S500, a near amorphous semiconducting polymer with a low degree of energetic disorder. It is topped with FE-D320 which is a low-k dielectric material that has been engineered to ensure a pristine interface with the semiconductor. The final organic layer is a crosslinkable dielectric material (FE-D048X) which is used to increase the electrical robustness. When processed together they have proven to achieve state-of-the-art device performance including a threshold close to 0V and an on/off ratio greater than 106. The field effect mobility is greater than 1.5 cm2/Vs which is higher than the ubiquitous amorphous silicon TFT technology used in most TFT-LCD glass displays. This shows that from an electrical performance prospective, FlexiOM™ materials are ideal for plastic LCDs.

OTFT backplane

OTFT manufacturing process

The manufacturing process for making OLCD on plastic is similar to making LCD on glass. However, some process steps require special consideration when organic materials are used as active layers. We have shown that the combination of FlexiOM™ materials and FlexEnable’s proprietary process technology make high-performing OTFT devices capable of driving beautiful liquid crystal displays. We’re excited to work with display makers to bring this technology to production.

For further information on our materials and processes, please contact us at info@flexenable.com.

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