CNT OLEDs

Many corporations and researchers have been investing a lot of money in the development of OLEDs.   

Researchers in Canada have demonstrated OLEDs based on carbon nanotube anodes that are as efficient as comparable indium tin oxide (ITO) devices. While this part seems to be only JUST equal, there are several advantages that the CNTs provide, such as increased material flexibility and hardiness. This could make them an attractive alternative to transparent conducting oxides for OLEDs.

Amazingly, many researchers say this method of creating OLEDs with CNTs is cheaper than using ITO.  Another current limitation of OLEDs is the transistors that the electric currents run along.  Right now, the current has to run ALONG the transistors, which means that for the OLED to be bright, and visible, the display has to be small.  Many Android smart phones are beginning to employ OLED screens.  This is the extent though.  OLEDs made with ITO are also, fragile, somewhat rigid and one sided.  By applying the appropriate chemical treatment, nanotubes could also replace the metal cathodes found in OLEDs. This would allow the devices to emit light from both sides. Not to mention that the OLEDs would be completely transparent, and as thin as 1 to 8 mm.

Another similar development in CNT OLEDs comes from The University of Southern California Viterbi School of Engineering.   USC is one of many groups around the world trying to perfect the technology in applications such as affordable "head-up" car windshield displays; eyeglasses to watch videos for when you are sitting in an airport or train station and ultra thin, low-power "e-paper" capable of full color motion video.

Chongwu Zhou of USCs Ming Hsieh Department of Electrical Engineering has been working on transparent electronics for the past three years and last year developed a prototype devices in which transparent electronics were built on top of a flexible transparent base.   This was accdomplished using carbon nanotubes.  Earlier attempts at transparent devices used other semiconductor materials with disappointing electronic results, enabling one kind of transistor (n-type); but not p-types; both types are needed for most applications.

The critical improvement in performance, according to the research, came from the ability to produce extremely dense, highly patterned lattices of nanotubes, rather than random tangles and clumps of the material. These new aligned nanotube transistors are easy to fabricate and integrate, as compared to individual nanotube devices. The transfer printing process allows the devices to be fabricated through low temperature processes, which is important for realizing transparent electronics on flexible substrates.

Zhou believes that we may be 2 to 6 years away from mass production of transparent electronics. One barrier is the inertia of old existing technology.

NOTE:  Samsung has released the first nanotube based OLED screen called "BluePhase".