Researchers develops transparent transistors via nanowires

Researchers from all over the world have always envisioned a day when windscreens will have transparent maps; eyeglasses will come integrated with TVs and many similar applications. For all these the main requirement is the development of a bendable and a fully transparent display. OLEDs or Organic Light-emitting diodes show us the way to design these hi-tech transparent displays. These diodes are currently found in cameras and mobile phones. Researchers already succeeded in making these diodes transparent but for a fully transparent display the transistors that control these diodes should also be made transparent.

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Taking this into mind researchers at the Purdue University and Northwestern University have developed flexible and transparent transistors using zinc-oxide and indium-oxide nanowires. These transistors also perform better than silicon transistors and can also easily be fabricated on flexible plastic.

According to the Purdue electrical- and computer-engineering professor, David Janes:

The transistors could lead to brighter see-through OLED displays

The findings also reveal that when conformist nontransparent transistor circuitry is placed around the OLED, it acquire place on the display or else it could be emitting light but Janes asserts that one can even put transparent transistors beneath or on the crest of the pixel to augment the light-emitting area.

To build these transistors, Janes and his colleagues initially deposited an indium-zinc-oxide gate electrode on glass or plastic and then nanowire solution was applied on the surface when they found aptly aligned nanowires they deposited source and drain electrodes made from indium tin oxide on each side of the nanowire. It is also noteworthy that both indium zinc oxide and indium tin oxide are transparent materials.

These nanowire transistors possess high electron mobility to determine transistor speed and current that it can carry, whereas, mobility is only few hundred times better for transistors developed by amorphous silicon that is commonly used in electronics for displays, and this is the reason behind that why, transistors could be made smaller and faster.

Janes also stated that more-compact transistors look for larger pixel area and nanowire transistors are very easy to make on plastic as compared to silicon transistors because they do not require high-temperature processing.

By using thin films of zinc oxide or indium oxide or by using carbon nanotubes the group of researchers has just made transparent transistors but both technologies face distinctive issues. However, carbon-nanotube transistors have much better electron mobilities and are stronger than the new nanowire transistors but they aren't fully transparent due to tiny metal contacts to connect the nanotubes to the electrodes that they require whereas, thin-film transistors are easier to fabricate on diverse surfaces but they have very low mobilities.

According to John Wager, an electrical-engineering and computer-science professor and who is also working in the area of transparent electronics at Oregon State University said, for the new transistors ‘the performance in terms of the mobility, flexibility, and transparency is very impressive,’ and now, the biggest query that arises is, ‘Can all of this be translated into real-world manufacturability?’

Presently, there is no method to control where nanowires get deposit on a surface or how they line up therefore an experiment is conducted which reveals that when you throw down couple of thousand nanotubes with expectation that they will allign in the direction you want, arbitrarily depositing nanowires on a surface doesn’t work, if you desire to manufacture transistors for large displays.

Janes further asserted:

You have to have some way of putting the desired number of nanowires in the location you want and at this point, all three technologies to make transparent transistors--nanowires, thin films, and carbon nanotubes--have a fair shot at replacing silicon transistor technology for future transparent, flexible displays.

According to John Rogers, a professor of materials science and engineering at the University of Illinois at Urbana Champaign , ‘it will be a good horse race to see which approach wins’ but the complete commercial success of one of the three technologies will rely on how they measure up on numerous unlike factors like transparency, electrical performance, flexibility and the ease and cost of manufacturing them.

But it is worth mentioning that this new development in the field of transistors, will surely prove an important innovation in the field of bright, flexible, and completely see-through displays.

Via: Technologyreview