Connect with us

Hi, what are you looking for?


Clean Power

Black Metals Beat A New Path To Solar Cell Efficiency

It looks like black is the new black when it comes to solar cell efficiency. A team of researchers at Lawrence Livermore National Laboratory (LLNL) has come up with a way to increase solar cell efficiency, by creating “black  metals” etched with nanoscale structures that harvest energy from wavelengths all along the solar spectrum. The idea is to take advantage of the plasmonic effect, and if the research develops apace it could enable the prime affordability target of the solar market to expand from high-sunlight locations to just about anywhere.

Along similar lines, we’ve been following “black silicon” research that uses nanoscale etching to increase solar absorption, so let’s take a closer took at both and see what’s going on.

Black Metals For Solar Cell Efficiency

The LLNL solar cell efficiency project, loosely speaking, involves “roughening up” metals at the nanoscale level, which is where the concept crosses paths with its silicon-based cousin. The random, nanoscale irregularities increase the number of reflections, trapping more light.

The result is a black surface that has lower reflectivity and higher absorption than the original material, covering both the visible and infrared sections of the spectrum.

According to writer Kenneth K Ma at LLNL, existing work in gold and silver black metals has come up against a fabrication obstacle, in which it has been difficult to replicate the full solar absorption rate.

The research team worked on that angle and developed a “nanopillar” structure that can be manipulated with more predictability, enabling the team to create metals “as  black as they want.”

black metals increase solar cel efficiency

LLNL has some competition out there, by the way. The research made the cover of Applied Physics Letters back in May, but a team from China also published the results of its work on light harvesting nanopillar structures in the publication’s online edition in April.

Also involved in the nanopillar horserace is UC-Santa Barbara, which has been developing a high efficiency solar cell based on a “forest of gold nanorods.”

Black Metals And The Plasmonic Effect

That leads us into the next question, which is how metals can generate an electrical charge from sunlight. Basically, it’s the same idea as semiconductors such as silicon, in which sunlight causes electrons to shift positions, leaving positively charged “holes.”

In metals, this shift creates free electrons and electromagnetic pulses similar to sound waves, called plasmons.

The nanorod approach provides one way to control and manipulate the plasmonic effect, but there are others. Over at Stanford University, for example, a team is working on a “waffle iron” plasmonic concept that involves creating nanoscale dimples in a layer of the semi-porous metal titania.

Meanwhile, a team at the University of Buffalo is testing out a low-efficiency but low-cost solar cell that incorporates the plasmonic effect into thin film organic solar cells. The idea is to create an affordable solar “paint” that could be applied to building surfaces.

On the meta-level, Duke University has been hot on the trail of an atomic-level explanation of the plasmonic effect, by studying the optical scattering that occurs when gold nanoparticles interact with a thin film of gold.

Follow me on Twitter and Google+.

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.

Former Tesla Battery Expert Leading Lyten Into New Lithium-Sulfur Battery Era — Podcast:

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!
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 Spoutible.


You May Also Like


The center at SLAC aims to bridge the gaps between discovering, manufacturing, and deploying innovative energy storage solutions


A polymer-based electrolyte made for batteries that keep working — and don’t catch fire — when heated to over 140 degrees F.

Cleantech News

Despite their supposed focus on sustainability, there seems to be an awful lot of fossil fuel and ‘big oil’ money creeping into university’s “green”...

Climate Change

Stanford University is the recipient of a $1.1 billion endowment to fund a sustainability and climate school. John and Ann Doerr have provided the...

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.