Connect with us

Hi, what are you looking for?



Record Breaking Solar Cell Efficiency From A “Perfect Crystal”

Gallium is already on its way to becoming the workhorse of the solar tech field, and now it looks like the soft metal is is on track to become a thoroughbred. A team of US scientists has hit upon an improved method for growing indium gallium nitride (InGaN) crystals that could lead to record-breaking solar cell efficiency. So far the method has resulted in a film of InGaN that has “almost ideal characteristics.”

To ice the cake, an analysis of the film revealed the precise reason why the results of the new InGaN growing method were so good, which could lead to further improvements in LED technology as well as solar cells.

A Perfect InGaN Crystal

Nitride refers to a compound of nitrogen, in this case in conjunction with indium, a soft silvery-white, zinc-like metal, as well as gallium.

record breaking solar cell efficiency from new InGaN crystals

InGaN LED light by Christian Pelant.

If InGaN already rings a bell, you might be thinking of the world record-setting concentrating solar cell module developed by the company Amonix. That module is based on a record setting solar cell developed by Solar Junction, that incorporates  a layer of antimony-doped InGaN.

Gallium in particular is an effective material for LEDs as well as solar cells due to its band gap characteristics, most familiarly in CIGS thin film solar cells (CIGS is the semiconductor copper-indium-gallium-(di)selenide). The potential has barely been scratched, though.

Arizona State University and the Georgia Institute of Technology collaborated on the new method, which addressed the problem at its core. The obstacle has been irregularities in the atomic structure of the crystal, as explained by ASU team leader Fernando Ponce:

Being able to ease the strain and increase the uniformity in the composition of InGaN is very desirable, but difficult to achieve. Growth of these layers is similar to trying to smoothly fit together two honeycombs with different cell sizes, where size difference disrupts a periodic arrangement of the cells.

The new method is called metal modulated epitaxy. It is a variation of the epitaxial deposition method first developed at Bell Labs in the 1960’s, which involves applying a thin layer of material to a substrate that takes on the crystal structure of the lower layer.

The result was a more film that resembles a perfect crystal, both in its uniformity of structure and in the desirable trait of luminosity.

As for why the improvement occurred, the analysis credited “strain relaxation at the first atomic layer of crystal growth.”

We Built This Next-Generation Solar Cell

Solar cell efficiency is not the only factor leading to a drop in the cost of solar power, since the “soft costs” of installing a solar system still account for a considerable chunk of change.

However, solar cell efficiency is still a key factor, and if the new findings translate from the lab to commercial development, let’s throw ourselves a taxpayer appreciation party.

The latest development has roots in a 2008 paper published by Georgia Tech team leader Alan Doolittle with other collaborators, titled “Metal modulation epitaxy growth for extremely high hole concentrations above 1019cm−3 in GaN.” It described how the metal modulated epitaxy method yielded an enhanced doping efficiency of up to 10 percent, which compares favorably to the 1 percent efficiency under the conventional method.

That research was funded by grants from the Office of Naval Research, the Air Force Office of Scientific Research, and the Defense Advanced Research Projects Agency as well as the National Science Foundation.

Follow me on Twitter and Google+

I don't like paywalls. You don't like paywalls. Who likes paywalls? Here at CleanTechnica, we implemented a limited paywall for a while, but it always felt wrong — and it was always tough to decide what we should put behind there. In theory, your most exclusive and best content goes behind a paywall. But then fewer people read it! We just don't like paywalls, and so we've decided to ditch ours. Unfortunately, the media business is still a tough, cut-throat business with tiny margins. It's a never-ending Olympic challenge to stay above water or even perhaps — gasp — grow. So ...
If you like what we do and want to support us, please chip in a bit monthly via PayPal or Patreon to help our team do what we do! Thank you!
Sign up for daily news updates from CleanTechnica on email. Or follow us on Google News!

Have a tip for CleanTechnica, want to advertise, or want to suggest a guest for our CleanTech Talk podcast? Contact us here.

Written By

Tina specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.


You May Also Like

Climate Change

AUSTIN, Texas — More of the world’s coastal glaciers are melting faster than ever, but exactly what’s triggering the large-scale retreat has been difficult...

Clean Transport

Unlike many press releases we see about solar car races, a recent one from Arizona State University gives us a lot more detail on...

Clean Power

Curiosity and Keen Observation Provide Insights for Next Generation of Thin-Film Solar Cells

Climate Change

A relatively tiny number of Permian oil and gas sites are responsible for a wildly disproportionate amount of methane pollution, a new study from...

Copyright © 2023 CleanTechnica. The content produced by this site is for entertainment purposes only. Opinions and comments published on this site may not be sanctioned by and do not necessarily represent the views of CleanTechnica, its owners, sponsors, affiliates, or subsidiaries.