High-performance OTFT technology – the way forward for flexible displays and flexible sensors

Mike Banach, Technical Director

May 23, 2016

Flexible electronics have captured the imagination of product designers for decades, but the transition from the drawing pad to reality has often left customers underwhelmed. Until now product makers and system integrators have been forced to compromise between performance and flexibility leaving the most attractive designs abandoned at the concept phase.

At FlexEnable we keep it simple. We believe the only way you can make truly flexible devices is to start with truly flexible materials, so we use plastics instead of ceramics to make our electronics. By keeping plastic electronics at the heart of what we do, we can enable a much broader range of product concepts. 

Plastic electronic materials explained

At the molecular level plastic electronic materials are long chains of carbon atoms. This is why making devices from electrically active plastic materials is often referred to as organic electronics. The most fundamental electrical device is the transistor and FlexEnable has a world- leading team of experts developing the highest performance, flexible organic thin-film transistors, or OTFT for short.

An exciting feature of OTFTs, which separates them from silicon devices, is that there is an unlimited scope for changing the chemical structure of the plastics used in the devices to improve performance. Over the last thirty years scientists have created thousands of new materials leading to an overall trend of increasingly effective OTFT devices. These materials, when placed in the hands of our experts at FlexEnable, have been used to make OTFT devices that have finally removed the need to compromise between performance and flexibility when creating electronic products. 

OTFT vs amorphous silicon

Organic transisitor array
Organic transistor array on plastic

The most widespread thin-film transistor for glass products on the market today is amorphous silicon. This technology has been tremendously successful over the past 30 years, ushering in the era of flat panel electronics. To this day amorphous silicon devices are used in the majority of displays in everything from televisions to phones. The devices can even be found in digital x-ray imagers that have replaced the film based systems in all modern hospitals. The success of amorphous silicon has made it the benchmark for electrical performance. Yet, that technology has not transitioned past the flat, rectangular, and somewhat fragile products that come with manufacturing on glass with ceramic-based active materials.

High-performance OTFT technology

FlexEnable has now shown that OTFT can meet and often surpass the electrical performance of amorphous silicon in all the critical areas.

First is speed or in transistor speak: mobility. OTFTs are now at least three times faster than amorphous silicon which means OTFTs can be used to make higher pixel density displays and sensors. The higher mobility also means OTFTs are well-positioned to address markets where highly dynamic brightness ranges are required to improve image quality.

Second is lifetime or stability. OTFTs are a great deal more stable to electrical stress than amorphous silicon which means it can easily match the lifetime of displays currently on the market.

Third is uniformity.  This is very important for large area devices and has been the pitfall for many emerging transistor technologies. The current generation of OTFTs at FlexEnable is as good as amorphous silicon, which is well known for having excellent uniformity.

The final important attribute is low leakage. This is especially important for sensor devices where the ability to store, charge and read an image back accurately defines the sensitivity of the product. Impressively, FlexEnable’s OTFT devices compare favourably with amorphous silicon with 100-1000 times better leakage currents.

Wristworn OLCD device
Conformable organic LCD (OLCD) that uses FlexEnable’s OTFT technology

The recent breakthroughs seen in OTFTs at FlexEnable have now pushed the technology beyond the amorphous silicon benchmark for electrical performance. Since OTFT has been developed from truly flexible plastic materials right from the start, it will always have an advantage in terms of enabling more exciting product designs.

Large area flexible fingerprint sensor
Flexible large area fingerprint sensor that uses FlexEnable’s OTFT technology

FlexEnable has carefully tailored the manufacturing process for its OTFT to make it compatible with existing flat panel production facilities which makes it cost effective solution for a mass production today. Just in time to save the next set of exciting product designs from ending up in the wastebasket.

If you want to find out more about our OTFT technology or use it in your product, get in touch at info@flexenable.com.

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