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

FEI Celebrates Shipment of 1,000th Helios DualBeam System: FEIís Helios Family has lead the DualBeam technology race and is widely used across the semiconductor, materials science, life sciences and oil & gas industries August 31st, 2016

Colors from darkness: Researchers develop alternative approach to quantum computing August 31st, 2016

Diamonds and quantum information processing on the nano scale August 31st, 2016

Device to control 'color' of electrons in graphene provides path to future electronics August 31st, 2016

Govt.-Legislation/Regulation/Funding/Policy

Device to control 'color' of electrons in graphene provides path to future electronics August 31st, 2016

Graphene key to growing 2-dimensional semiconductor with extraordinary properties August 30th, 2016

New approach to determining how atoms are arranged in materials August 25th, 2016

Johns Hopkins scientists track metabolic pathways to find drug combination for pancreatic cancer August 25th, 2016

Possible Futures

Colors from darkness: Researchers develop alternative approach to quantum computing August 31st, 2016

Device to control 'color' of electrons in graphene provides path to future electronics August 31st, 2016

Graphene key to growing 2-dimensional semiconductor with extraordinary properties August 30th, 2016

Nanocatalysis for organic chemistry: This research article by Dr. Qien Xu et al. is published in Current Organic Chemistry, Volume 20, Issue 19, 2016 August 30th, 2016

Materials/Metamaterials

Device to control 'color' of electrons in graphene provides path to future electronics August 31st, 2016

Graphene key to growing 2-dimensional semiconductor with extraordinary properties August 30th, 2016

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Graphene under pressure August 26th, 2016

Announcements

FEI Celebrates Shipment of 1,000th Helios DualBeam System: FEIís Helios Family has lead the DualBeam technology race and is widely used across the semiconductor, materials science, life sciences and oil & gas industries August 31st, 2016

Colors from darkness: Researchers develop alternative approach to quantum computing August 31st, 2016

Diamonds and quantum information processing on the nano scale August 31st, 2016

Device to control 'color' of electrons in graphene provides path to future electronics August 31st, 2016

Environment

Nanofur for oil spill cleanup: Materials researchers learn from aquatic ferns: Hairy plant leaves are highly oil-absorbing / publication in bioinspiration & biomimetics / video on absorption capacity August 25th, 2016

Researchers watch catalysts at work August 19th, 2016

Down to the wire: ONR researchers and new bacteria August 18th, 2016

SLAC, Stanford gadget grabs more solar energy to disinfect water faster: Plopped into water, a tiny device triggers the formation of chemicals that kill microbes in minutes August 15th, 2016

Energy

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Lehigh engineer discovers a high-speed nano-avalanche: New findings published in the Journal of Electrochemical Society about the process involving transformations in glass that occur under intense electrical and thermal conditions could lead the way to more energy-efficient glas August 24th, 2016

New flexible material can make any window 'smart' August 23rd, 2016

Researchers reduce expensive noble metals for fuel cell reactions August 22nd, 2016

Research partnerships

Device to control 'color' of electrons in graphene provides path to future electronics August 31st, 2016

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

New theory could lead to new generation of energy friendly optoelectronics: Researchers at Queen's University Belfast and ETH Zurich, Switzerland, have created a new theoretical framework which could help physicists and device engineers design better optoelectronics August 23rd, 2016

A new way to display the 3-D structure of molecules: Metal-organic frameworks provide a new platform for solving the structure of hard-to-study samples August 21st, 2016

Solar/Photovoltaic

Let's roll: Material for polymer solar cells may lend itself to large-area processing: 'Sweet spot' for mass-producing polymer solar cells may be far larger than dictated by the conventional wisdom August 12th, 2016

NREL technique leads to improved perovskite solar cells August 11th, 2016

Making a solar energy conversion breakthrough with help from a ferroelectrics pioneer: Philadelphia-based team shows how a ferroelectric insulator can surpass shockley-queisser limit August 9th, 2016

Tiny high-performance solar cells turn power generation sideways August 5th, 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