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Ankita Katdare
Ankita Katdare • Apr 29, 2015

Make Displays Transparent Or Opaque In A Matter Of Milliseconds

What might seem to have come straight out of a sci-fi movie, the new research work done by the South Korean Pusan National University team may leave you spellbound. Imagine sitting in your office and having a window that can be made transparent or opaque on your whim and fancy. That looks possible with the transparent light shutters developed by these researchers. It has been a dream of scientists to develop transparent displays. However, using organic light-emitting diodes to create them has been proven to be difficult. One proposed solution for this is light shutters which use liquid crystals that can be switched between transparent and opaque states by scattering or absorbing the incident light. But then, this method has its own set of disadvantages. Scattering can't provide black colour and Absorbing can't completely block the background. Moreover, they suffer from lack of energy efficiency and have very low response time on switching power on or off.

In the Pusan University research team's work, they found a solution to all these problems by employing scattering and absorption of light simultaneously. For this they had to fabricate polymer-networked liquid crystals (for scattering) cells doped with dichroic dyes (for absorbing). The light shutters has electrodes located parallely above and below the vertically aligned liquid crystals. On passing an electric field through these electrodes, the axes of dye molecules are aligned with coming light. This negates the light coming from backside, thus rendering the display opaque and the viewer can still see the screen's images.

ADV-Yoon-smart windows-resized
A dye-doped PNLC cell in the transparent and opaque states,
placed on a printed sheet of paper.​

The system is power efficient as power is only needed when ones wants to switch from transparent window view to opaque monitor view. Moreover, the response time is < 1 millisecond as the display's on-off switch is an electric field.

The team is now working on increase and decrease of the device's transmittance at the transparent and opaque states. They also hope to make the device more energy efficient by developing a bi-stable light shutter that consumes power only when states are being switched, instead of using it all the while at maintaining the state.

How about having a transparent display on the windshield of your car that displays the desired information while you driving? We are already hoping that our sci-fi fantasies might just come true in the years to come. When it comes to transparent displays, we remember work done by MIT researchers and undisputed king of advancements in display technology - Samsung who revealed its work in Transparent LCD Display back in 2011.

What are your thoughts about the new research work? Share with us in comments below.

Source: Science Daily

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