Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Forcing mismatched elements together could yield better solar cells

Abstract:
In what could be a step toward higher efficiency solar cells, an international team including University of Michigan professors has invalidated the most commonly used model to explain the behavior of a unique class of materials called highly mismatched alloys.

Forcing mismatched elements together could yield better solar cells

Ann Arbor, MI | Posted on September 10th, 2010

U-M professors from the departments of Materials Science and Engineering, and Physics contributed to this research.

Highly mismatched alloys, which are still in the experimental stages of development, are combinations of elements that won't naturally mix together using conventional crystal growth techniques. Professor Rachel Goldman compares them to some extent to homogenized milk, in which the high-fat cream and low-fat milk that would naturally separate are forced to mix together at high pressure.

New mixing methods such as "molecular beam epitaxy" are allowing researchers to combine disparate elements. The results, Goldman says, are more dramatic than smooth milk.

"Highly mismatched alloys have very unusual properties," said Goldman, a professor in the departments of Materials Science and Engineering, and Physics. "You can add just a sprinkle of one element and drastically change the electrical and optical properties of the alloy."

Solar cells convert energy from the sun into electricity by absorbing light. However, different materials absorb light at different wavelengths. The most efficient solar cells are made of multiple materials that together can capture a greater portion of the electromagnetic radiation in sunlight. The best solar cells today are still missing a material that can make use of a portion of the sun's infrared light.

Goldman's team made samples of gallium arsenide nitride, a highly mismatched alloy that is spiked with nitrogen, which can tap into that underutilized infrared radiation.

The researchers used molecular beam epitaxy to coax the nitrogen to mix with their other elements. Molecular beam epitaxy involves vaporizing pure samples of the mismatched elements and combining them in a vacuum.

Next, the researchers measured the alloy's ability to convert heat into electricity. They wanted to determine whether its 10 parts per million of nitrogen were distributed as individual atoms or as clusters. They found that in some cases, the nitrogen atoms had grouped together, contrary to what the prevailing "band anti-crossing" model predicted.

"We've shown experimentally that the band anti-crossing model is too simple to explain the electronic properties of highly mismatched alloys," Goldman said. "It does not quantitatively explain several of their extraordinary optical and electronic properties. Atomic clusters have a significant impact on the electronic properties of alloy films."

If researchers can learn to control the formation of these clusters, they could build materials that are more efficient at converting light and heat into electricity, Goldman said.

"The availability of higher efficiency thermoelectrics would make it more practical to generate electricity from waste heat such as that produced in power plants and car engines," Goldman said.

This research will be published in the Sept. 15 issue of Physical Review B. The paper is entitled "Nitrogen composition dependence of electron effective mass in gallium arsenide nitride." Authors include Goldman, as well as Cagliyan Kurdak, an associate professor in the Department of Physics, and Ctirad Uher, a professor in the Department of Physics.

This research was conducted in laboratories of the Center for Solar and Thermal Energy Conversion (CSTEC), a Department of Energy Energy Frontiers Research Center at the University of Michigan. The research was funded by the National Science Foundation, the Science Foundation Ireland, and CSTEC.

####

For more information, please click here

Contacts:
Nicole Casal Moore
(734) 647-7087

Copyright © University of Michigan

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 News Press

News and information

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Quantum shift shows itself in coupled light and matter: Rice University scientists corral, quantify subtle movement in condensed matter system April 16th, 2018

When superconductivity disappears in the core of a quantum tube: By replacing the electrons with ultra-cold atoms, a group of physicists has created a perfectly clean material, unveiling new states of matter at the quantum level April 16th, 2018

Possible Futures

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Materials/Metamaterials

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Individual impurity atoms detectable in graphene April 18th, 2018

Psst! A whispering gallery for light boosts solar cells April 14th, 2018

Artificial intelligence accelerates discovery of metallic glass: Machine learning algorithms pinpoint new materials 200 times faster than previously possible April 13th, 2018

Announcements

Remote-control shoots laser at nano-gold to turn on cancer-killing immune cells April 20th, 2018

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Observing biological nanotransporters: Chemistry April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Environment

'Sweet spot' in sweet material for hydrogen storage: Study IDs 'white graphene' architecture with unprecedented hydrogen storage capacity March 12th, 2018

Converting CO2 into Usable Energy: Scientists show that single nickel atoms are an efficient, cost-effective catalyst for converting carbon dioxide into useful chemicals March 1st, 2018

Ultra-efficient removal of carbon monoxide using gold nanoparticles on a molecular support: New method and mechanism for state-of-the-art gas purification February 9th, 2018

New filters could enable manufacturers to perform highly-selective chemical separation January 23rd, 2018

Energy

Psst! A whispering gallery for light boosts solar cells April 14th, 2018

High efficiency solar power conversion allowed by a novel composite material: A composite thin film developed at INRS improves significantly solar cells' power conversion efficiency April 10th, 2018

Light 'relaxes' crystal to boost solar cell efficiency: Rice, Los Alamos discovery advances case for perovskite-based solar cells April 6th, 2018

Double perovskites in environmentally friendly solar cells: Long electron-hole diffusion length in high-quality lead-free double perovskite films April 6th, 2018

Research partnerships

New qubit now works without breaks: A universal design for superconducting qubits has been created April 19th, 2018

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Psst! A whispering gallery for light boosts solar cells April 14th, 2018

Artificial intelligence accelerates discovery of metallic glass: Machine learning algorithms pinpoint new materials 200 times faster than previously possible April 13th, 2018

Solar/Photovoltaic

Salt boosts creation of 2-D materials: Rice University scientists show how salt lowers reaction temperatures to make novel materials April 18th, 2018

Psst! A whispering gallery for light boosts solar cells April 14th, 2018

High efficiency solar power conversion allowed by a novel composite material: A composite thin film developed at INRS improves significantly solar cells' power conversion efficiency April 10th, 2018

Light 'relaxes' crystal to boost solar cell efficiency: Rice, Los Alamos discovery advances case for perovskite-based solar cells April 6th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project