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"Nanoscale sandwich" technique could mean thinner, cheaper solar cells

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June 25, 2012

Using what they call the 'nanoscale sandwich' technique, researchers have created ultra-th...

Using what they call the 'nanoscale sandwich' technique, researchers have created ultra-thin solar cells that are just as efficient as conventional thicker ones (Photo via Shutterstock)

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We certainly hear a lot about solar cells that are able to convert larger and larger percentages of the sun’s energy into electricity. That’s all very well and good, but if those more-efficient solar cells are too expensive, they will still ultimately prove impractical for everyday use. Researchers from North Carolina State University, however, have found a way of creating “ultra-thin” solar cells that should create just as much electricity as their thicker siblings, but at a lower cost.

The new cells are made using what is called a “nanoscale sandwich” design. The process starts with a pattern being laid down on a transparent dielectric substrate, using regular lithography techniques. That pattern forms the substrate into tiny structures measuring between 200 and 300 nanometers in height – when viewed in cross-section, they resemble the crenelations along the top of a medieval castle.

A diagram of the 'nanoscale sandwich' structure

Next, a very thin layer of the active material is deposited onto the altered substrate. This “active layer” is what actually converts the solar energy into electricity. Finally, on top of that layer, another layer of the dielectric material is deposited. This results in a dielectric/active material/dielectric sandwich.

The crenelated shape of this sandwich allows the two dielectric layers to serve as highly-efficient optical antennas, focusing the solar energy onto the layer of active material – this means that less of that material can be used, without a loss in performance.

“We created a solar cell with an active layer of amorphous silicon that is only 70 nanometers (nm) thick,” said Dr. Linyou Cao, co-author of a paper on the research. “This is a significant improvement, because typical thin-film solar cells currently on the market that also use amorphous silicon have active layers between 300 and 500 nm thick.”

He added that the same technique could be used to create solar cells incorporating other active materials, such as cadmium telluride, copper indium gallium selenide, and organic materials.

His paper was recently published in the journal Nano Letters.

Source: North Carolina State University

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
5 Comments

Too expensive? Where have these people been? I buy PV for $1/wt retail. It costs more to install and gird tie than the panels cost. I buy lams for $.50/wt and make frames, build them into my roof cutting cost by 75% more vs hiring others, paying retail for the services.

Fact is shopped righ,t PV is cheaper than retail nuke, coal, NG is in most places.

sunelec.com is just one source.

What solar/RE, the world needs is the full costs of nuke, coal and oil put in their price instead of in our taxes, health, oil wars, etc costs and cutting out laws, regs that give FFuels a monopoly like here in Fla.

jerryd
26th June, 2012 @ 10:26 am PDT

For years Gizmag has regularly posted articles about new solar cell improvements, often promising lower costs (like this one), lighter weight, improved efficiency.

But "old tech" solar cells are what's available in the stores.

Jerryd's comment about State and Federal government subsidies hiding the real costs of Fossil Fuel and Nuclear power is a fact that is obvious to every thinking person - he's absolutely right.

But what I can't help but wonder is what "negative" subsidies and disincentives are applied by the Carbon Club to keep all these wonderful tech improvements from showing up in the stores.

Changes in computer tech show up on retail shelves two or three times a year with major advances. Yet solar technology despite major discoveries and new techniques somehow short-out.

Richard Chesher
26th June, 2012 @ 01:24 pm PDT

It's all about the cost of retooling their manufacturing facilities and how long it would take recoup the investment. They have a problem realizing that if what they manufactured was lower in cost that they could sell more of them and still make a good profit even at a lower unit cost to the public or other manufacturers.

Billy Brooks
26th June, 2012 @ 11:54 pm PDT

Im always surprised by the near obsession with large scale solar systems. I dont see that the total efficiency increases by being larger - probably less if there is more mass distribution inefficiencies. There are plenty of solar products that can benefit individual life without a massive investment.

SolarLightCap.com is one example.

Just use what you need people - and help sustain the planet.

SimonSolar2C
27th June, 2012 @ 05:33 am PDT

A few years ago when the 'sliver cell' technology was announced I spoke to the then GM of the company involved about pricing. He told me that they expected pricing to be the same as every other panel, minus $1

As per most short-sighted businesses, they were wanting to maximise rate of return. I pointed out that if they took advanced orders for their cells at a substantially cheaper retail cost than the dominant players whilst the manufacturing facility was being built, they'd block out the incumbent competition and launch a whole new customer base at the same time.

'Too difficult' was the essence of the reply

So whilst this idea (and others like it) have the 'potential' to deliver a more cost effective panel, the sad reality is that short termism of ROI will see it priced the same or higher than existing PVs

Strategic Futurist
27th June, 2012 @ 10:47 pm PDT
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