Smallest pixels ever created could light up color-changing buildings

Smallest pixels ever created could light up color-changing buildings
eNPoMs formed from gold nanoparticles (Au NPs) encapsulated in a conductive polymer shell. Credit: NanoPhotonics Cambridge/Hyeon-Ho Jeong, Jialong Peng

The smallest pixels yet created—a million times smaller than those in smartphones, made by trapping particles of light under tiny rocks of gold—could be used for new types of large-scale flexible displays, big enough to cover entire buildings.

The colour pixels, developed by a team of scientists led by the University of Cambridge, are compatible with roll-to-roll fabrication on flexible plastic films, dramatically reducing their production cost. The results are reported in the journal Science Advances.

It has been a long-held dream to mimic the colour-changing skin of octopus or squid, allowing people or objects to disappear into the natural background, but making large-area flexible display screens is still prohibitively expensive because they are constructed from highly precise multiple layers.

At the centre of the pixels developed by the Cambridge scientists is a tiny particle of gold a few billionths of a metre across. The grain sits on top of a reflective surface, trapping light in the gap in between. Surrounding each grain is a thin sticky coating which changes chemically when electrically switched, causing the to change colour across the spectrum.

The team of scientists, from different disciplines including physics, chemistry and manufacturing, made the pixels by coating vats of golden grains with an active polymer called polyaniline and then spraying them onto flexible mirror-coated plastic, to dramatically drive down production cost.

The pixels are the smallest yet created, a million times smaller than typical smartphone pixels. They can be seen in bright sunlight and because they do not need constant power to keep their set colour, have an energy performance that make large areas feasible and sustainable. "We started by washing them over aluminized food packets, but then found aerosol spraying is faster," said co-lead author Hyeon-Ho Jeong from Cambridge's Cavendish Laboratory.

"These are not the normal tools of nanotechnology, but this sort of radical approach is needed to make sustainable technologies feasible," said Professor Jeremy J Baumberg of the NanoPhotonics Centre at Cambridge's Cavendish Laboratory, who led the research. "The strange physics of light on the nanoscale allows it to be switched, even if less than a tenth of the film is coated with our active pixels. That's because the apparent size of each pixel for light is many times larger than their physical area when using these resonant gold architectures."

The pixels could enable a host of new application possibilities such as building-sized display screens, architecture which can switch off solar heat load, active camouflage clothing and coatings, as well as tiny indicators for coming internet-of-things devices.

The team are currently working at improving the colour range and are looking for partners to develop the technology further.


Explore further

First graphene-based flexible display produced

More information: "Scalable electrochromic nanopixels using plasmonics" Science Advances (2019). DOI: 10.1126/sciadv.aaw2205 , https://advances.sciencemag.org/content/5/5/eaaw2205
Journal information: Science Advances

Citation: Smallest pixels ever created could light up color-changing buildings (2019, May 10) retrieved 15 September 2019 from https://phys.org/news/2019-05-smallest-pixels-color-changing.html
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May 10, 2019
Urban areas already glow, so there might as well be bright nights all the time too.

May 10, 2019
Before everyone gets to enthusiastic
coating surfaces and buildings with smaller and smaller nano particles
inevitably means more and more of these nano particles blowing in the wind
where these particles getting in the food chain
being breathed in
where at a point of overreaching what the human body can withstand
these nano particles are already creating rubbish of their own
which individually cannot be seen
but our molecular cells can see them because they can pass though our pores and lungs
When the Chinese start making these then is the time to start worrying

May 11, 2019
Before everyone gets to enthusiastic
coating surfaces and buildings with smaller and smaller nano particles
inevitably means more and more of these nano particles blowing in the wind
where these particles getting in the food chain
being breathed in
where at a point of overreaching what the human body can withstand
these nano particles are already creating rubbish of their own
which individually cannot be seen
but our molecular cells can see them because they can pass though our pores and lungs
When the Chinese start making these then is the time to start worrying

Well then. Hopefully it's monoatomic..

May 11, 2019
More cluttering up the sky with excess light. Do these greedy m---------- know what they are doing to the biological cycles of humans? 95% of people in 20 years will live in major cities, we do not need more nighttime light pollution. Noise to the extent that it can be, is controlled. So should light be.

May 11, 2019
More cluttering up the sky with excess light. Do these greedy m---------- know what they are doing to the biological cycles of humans? 95% of people in 20 years will live in major cities, we do not need more nighttime light pollution. Noise to the extent that it can be, is controlled. So should light be.

I guess blackout curtains and or sleep masks would be too advanced for most people to purchase?

May 12, 2019
More cluttering up the sky with excess light. Do these greedy m---------- know what they are doing to the biological cycles of humans? 95% of people in 20 years will live in major cities, we do not need more nighttime light pollution. Noise to the extent that it can be, is controlled. So should light be.

I guess blackout curtains and or sleep masks would be too advanced for most people to purchase?


People rarely spend 8 hours in bed nowadays, so even being out at night, you shouldn't be exposed to light levels like daytime.

May 12, 2019
On buildings? Not so much. But I'd very much love to have wallpaper on which I could play selected background scenes (or merely other wallpaper textures if this doesn't use constant power)...or just have a wall-filling screen for movies instead of my current projector rig.

May 12, 2019
Beware, you have been warned

If these are monoatomic elements like helium….
In other words, natural elements the human body has evolved to live with
but
if these are plastics, solvents, metals that our molecular cells cannot handle
Go right ahead
Fill this environment with this nano toxic rubbish that only our molecular cells can see
so when you fall ill with your body infested with theses nano particles
just do not complain when the surgeons tell you there is no way of removing this toxic rubbish
because
It is too small to see!

May 12, 2019
The technology described in this article does not generate light. It is an electro-chromic technology, not a photo-generation technology. As described, it operates in ambient light. If you wanted to see the colors, you have to provide the light yourself. From the paper:

"The key feature is that the nanoparticles strongly confine light within their individual gaps to the underlying mirror and thus produce extremely localized cavity resonances (Fig. 1), making them independent and insensitive to the angle and polarization of the incident light."

May 12, 2019
The technology described in this article does not generate light. It is an electro-chromic technology, not a photo-generation technology. As described, it operates in ambient light. If you wanted to see the colors, you have to provide the light yourself. From the paper:

"The key feature is that the nanoparticles strongly confine light within their individual gaps to the underlying mirror and thus produce extremely localized cavity resonances (Fig. 1), making them independent and insensitive to the angle and polarization of the incident light."

So... it's a movie screen...

May 13, 2019
More cluttering up the sky with excess light. Do these greedy m---------- know what they are doing to the biological cycles of humans? 95% of people in 20 years will live in major cities, we do not need more nighttime light pollution. Noise to the extent that it can be, is controlled. So should light be.

Living in one those super bright cities, where during the summer I can only see 2 maybe 3 stars, the planets, the moon and clouds up in the sky at night, I can say its odd and uninspiring. It does make me consider moving to a better place, a place with stars at night in the sky.

I wonder what these inhabitants here would say of they woke up one morning and their city had removed all the trees, or all the lakes nearby.

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