Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Nanoconfinement of Organic Solar Cell Material Enhances Conductivity: Nanometer-scale restructuring doubles electricity output for the same amount of absorbed sunlight

Abstract:
By Karen McNulty Walsh

Sometimes a change in surroundings makes all the difference. That's the approach a group of researchers at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory has used to improve the electricity output of a semiconductor material used in polymer-based solar cells. By confining the light-absorbing/charge-separating material within nanometer-scale pores, instead of using it in continuous thin-film sheets, the scientists enhanced the material's electrical conductivity by more than 500 times - and produced solar cells with twice the electricity output for the same amount of absorbed sunlight.

Nanoconfinement of Organic Solar Cell Material Enhances Conductivity: Nanometer-scale restructuring doubles electricity output for the same amount of absorbed sunlight

Upton, NY | Posted on October 20th, 2011

The advance doesn't improve overall solar-cell efficiency, however, because the nano-confined light-absorbing material doesn't cover as much area as in the thin-film format. But the research suggests that such nanoscale restructuring, described in the cover article of the October 17, 2011, issue of Applied Physics Letters and in the September 13, 2011, issue of ACS Nano, might eventually achieve that goal, and make polymer-based solar cells - potentially manufactured as inexpensively as plastics - more competitive in the marketplace.

"Judged by their physical properties, organic semiconductors should be more efficient at converting sunlight to electricity than they are," said Charles Black, group leader for electronic materials at Brookhaven's Center for Functional Nanomaterials (CFN). "One of the goals of our research is to understand why - and to devise new solar cell architectures to improve them."

The team, including materials scientist Jonathan Allen and other Brookhaven collaborators, focused its attention on a common blend of organic materials used in polymer-based solar devices. The blend is typically used as a thin film sheet between two conducting metal electrodes. Incident sunlight "excites" electrons in the organic semiconductor and produces electron-hole pairs. The blend helps separate these pairs and sends the electron to one electrode and the hole to the other in order to produce electricity.

"While the organic blend is very efficient at splitting electron-hole pairs, it's not so good at transporting them out," Allen said.

To understand why, the scientists partnered with Kevin Yager (CFN) and Ben Ocko (Condensed Matter Physics Department) to examine the material using bright beams of x-rays at Brookhaven's National Synchrotron Light Source (NSLS). By measuring the angles at which x-rays diffracted around molecules composing the organic film, the scientists determined that the molecules packed in such a way to enhance electrical conductivity in the plane of the film, but not perpendicular to it.

"Solar cells need electrons and holes to move in the out-of-plane direction - that is, toward the conductors designed to collect the current," said Allen. "So we decided to try turning the material on its side by confining it to spaces more elongated in the out-of-plane direction."

Back at the CFN, the scientists created a template of tiny holes measuring 60 nanometers in diameter and about 110 nanometers deep. Instead of generating each hole one by one, they used an electrochemical method to self-assemble arrays of billions of pores per square centimeter in a piece of aluminum foil.

"Flowing an electric current in an electrolyte will oxidize the aluminum in a particular way, creating regular arrays of nanometer-scale holes," said Allen. "We can do this over large areas without the need for any specialized tools," he added.

Then the scientists filled the holes with the polymer blend, added metal conductor layers on top and bottom, and measured the current produced while illuminating the device with artificial sunlight.

"The out-of-plane conductivity of the material confined to the holes is 500 times better than when it is formed as a thin film," said Allen.

But the scientists were surprised upon measuring the crystal structure of the nanoconfined material at the NSLS. Instead of seeing crystals aligned in the out-of-plane direction - as if the material had been turned on its side - they saw no alignment to the crystal arrangement whatsoever.

"We didn't expect such a highly conducting material to be randomly oriented, but it is," said Ocko.

The team believes the orientation of crystal stacking in a thin film arrangement actively blocks the out-of-plane movement of electrical current. However, confining the same material within nanopores inhibits such long-range crystal alignment, thus removing the roadblocks to out-of-plane current flow.

Solar cells made from the reconfigured material produce twice as much electricity for the same amount of absorbed sunlight, compared to an unconfined, continuous film. While this is a substantial improvement in the material performance, the overall solar device efficiency remains unimproved because the confining nanostructured template occupies valuable space. And that space is not generating electricity.

The team is exploring ways to minimize that wasted space to better leverage the improved material performance. They also plan to investigate whether the nano-containment approach could provide similar benefits for other organic solar materials.

"We're excited about the research directions these results suggest," said Black. "They play to the strengths of the CFN, making great use of Brookhaven's capabilities to correlate a material's structure to its electrical function - and ultimately to improve its performance."

This work was funded by the Department of Energy's Office of Science and by Brookhaven's Laboratory Directed Research and Development program.

Visit Brookhaven Lab's electronic newsroom for links, news archives, graphics, and more or follow Brookhaven Lab on Twitter.

####

About Brookhaven National Laboratory

The Center for Functional Nanomaterials at Brookhaven National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories. For more information about the DOE NSRCs, please visit nano.energy.gov.

For more information, please click here

Contacts:
Brookhaven National Laboratory
Media & Communications Office
Bldg. 400 - P.O. Box 5000
Upton, NY 11973
Phone: (631)344-8350
Fax: (631)344-3368

Copyright © Brookhaven National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Improved Power Conversion Efficiency in Bulk Heterojunction Organic Solar Cells with Radial Electron Contacts:

Enhanced Charge Collection in Confined Bulk Heterojunction Organic Solar Cells:

Related News Press

News and information

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

Laboratories

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

ORNL demonstrates large-scale technique to produce quantum dots May 21st, 2016

Scientists take a major leap toward a 'perfect' quantum metamaterial: Berkeley Lab, UC Berkeley researchers lead study that uses trapped atoms in an artificial crystal of light May 13th, 2016

Atomic force microscope reveals molecular ghosts: Mapping molecules with atomic precision expands toolbox for designing new catalytic reactions May 11th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Thermal modification of wood and a complex study of its properties by magnetic resonance May 26th, 2016

Discoveries

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

Announcements

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

Energy

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

Technique improves the efficacy of fuel cells: Research demonstrates a new phase transition from metal to ionic conductor May 18th, 2016

Solar/Photovoltaic

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

This 'nanocavity' may improve ultrathin solar panels, video cameras and more May 16th, 2016

New research shows how silver could be the key to gold-standard flexible gadgets: Silver nanowires are an ideal material for current and future flexible touch-screen technologies May 13th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic