Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Better solar cells, better LED light and vast optical possibilities

Electron microscope picture of wurtzite GaA/AIGaAs core-shell nanowires.(Dr. Dheeraj Dasa and Prof. Helge Weman, NTNU).
Electron microscope picture of wurtzite GaA/AIGaAs core-shell nanowires.
(Dr. Dheeraj Dasa and Prof. Helge Weman, NTNU).

Abstract:
Changes at the atom level in nanowires offer vast possibilities for improvement of solar cells and LED light. NTNU-researchers have discovered that by tuning a small strain on single nanowires they can become more effective in LEDs and solar cells.



CrayoNano AS introduces a hybrid material with unique properties. This is obtained by growing semiconductor nanowires on graphene.

Better solar cells, better LED light and vast optical possibilities

Gloshaugen, Norway | Posted on April 12th, 2014

NTNU researchers Dheeraj Dasa and Helge Weman have, in cooperation with IBM, discovered that gallium arsenide can be tuned with a small strain to function efficiently as a single light-emitting diode or a photodetector. This is facilitated by the special hexagonal crystal structure, referred to as wurtzite, which the NTNU researchers have succeeded in growing in the MBE lab at NTNU. The results were published in Nature Communications this week.

The last few years have seen significant breakthroughs in nanowire and graphene research at NTNU. In 2010, Professors Helge Weman, Bjørn-Ove Fimland and Ton van Helvoort and their academic group went public with their first groundbreaking discoveries within the field.

The researchers, who specialise on growing nanowires, had succeeded in controlling a change in the crystal structure during nanowire growth. By altering the crystal structure in a substance, i.e. changing the positions of the atoms, the substance can gain entirely new properties. The NTNU researchers discovered how to alter the crystal structure in nanowires made of gallium arsenide and other semiconductors.

With that, the foundation was laid for more efficient solar cells and LEDs.

- Our discovery was that we could manipulate the structure, atom by atom. We were able to manipulate the atoms and alter the crystal structure during the growth of the nanowires. This opened up for vast new possibilities. We were among the first in the world who were able to create a new gallium arsenide material with a different crystal structure, says Helge Weman at the Department of Electronics and Telecommunications.

This process exists in nature as well. For example, diamond and graphite - the latter is used as the "lead" in pencils - are composed by the same carbon atoms. But their crystal structures are different.

And now, researchers can also change the structure of nanowires at the atom level.

Graphene, the super-material

The next big news came in 2012. At that point, the researchers had managed to make semiconductor nanowires grow on the super-material graphene. Graphene is the thinnest and strongest material ever made. This discovery was described as a revolution in solar cell and LED component development.

Over time, graphene can replace silicon as a component in electronic circuits. Today, silicon is used for producing both electronics and solar cells. Graphene conducts electricity 100 times faster than silicon, and is only one atom thick, while a silicon wafer is normally millions of times thicker. Graphene will also likely be cheaper than silicon in just a few years.

The research group has received a lot of international attention for the graphene method. Helge Weman and his NTNU co-founders Bjørn-Ove Fimland and Dong-Chul Kim have established the company CrayoNano AS, working with a patented invention that grows semiconductor nanowires on graphene. The method is called molecular beam epitaxy (MBE), and the hybrid material has good electric and optical properties.

- We are showing how to use graphene to make much more effective and flexible electronic products, initially solar cells and white light-emitting diodes (LED). The future holds much more advanced applications, says Weman.

Highly effective solar cells

- Our goal is to create solar cells that are more effective than when they are made with thin film technology, Weman emphasises.

Thin film technology is a term from the solar cell technology. This technology develops super-thin solar cell panels, where the active layer converting sunlight to electricity has a thickness of no more than three micrometres, i.e. three thousands of a millimetre. The low weight allows easy transportation, installation and maintenance of the solar cells, and they can in practice be rolled out like roofing felt on most buildings.

Now, the combination of nanowires and graphene facilitates much broader and more flexible solar cells.

In thin films like gallium arsenide, the atoms are placed cubically in a fixed, predefined structure. When the researchers manipulate the atom structure inside the nanowire, they can grow both cubic and hexagonal crystal structures. The different structures have completely different properties, for example when it comes to optical properties.

New discoveries, new possibilities

The last couple of years the research group has, among other things, studied the unique hexagonal crystal structure in the GaAs nanowires.

- In cooperation with IBM, we have now discovered that if we stretch these nanowires, they function quite well as light-emitting diodes. Also, if we press the nanowires, they work quite well as photodetectors. This is facilitated by the hexagonal crystal structure, called wurtzite. It makes it easier for us to change the structure to optimise the optical effect for different applications.

- It also gives us a much better understanding, allowing us to design the nanowires with a built-in compressive stress, for example to make them more effective in a solar cell. This can for instance be used to develop different pressure sensors, or to harvest electric energy when the nanowires are bent, Weman explains.

Because of this new ability to manipulate the nanowires' crystal structure, it is possible to create highly effective solar cells that produce a higher electric power. Also, the fact that CrayoNano now can grow nanowires on super-light, strong and flexible graphene, allows production of very flexible and lightweight solar cells.

The CrayoNano group will now also start growing gallium nitride nanowires for use in white light-emitting diodes.

- One of our objectives is to create gallium nitride nanowires in a newly installed MBE machine at NTNU to create light-emitting diodes with better optical properties - and grow them on graphene to make them flexible, lightweight and strong.

####

About The Norwegian University of Science and Technology (NTNU)
The Norwegian University of Science and Technology (NTNU) in Trondheim represents academic eminence in technology and the natural sciences as well as in other academic disciplines ranging from the social sciences, the arts, medicine, architecture to fine arts. Cross-disciplinary cooperation results in ideas no one else has thought of, and creative solutions that change our daily lives.

For more information, please click here

Contacts:
Helge Weman
NTNU
+ 47 91897658

Copyright © AlphaGalileo

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

Protein Building Blocks for Nanosystems: Scientists develop method for producing bio-based materials with new properties April 17th, 2015

Oxford Instruments commissions high field outsert magnet system for the National High Magnetic Field Laboratory 32 Tesla magnet program April 17th, 2015

QD Vision Expands Product Line with Two-Millimeter Color LCD Display Optic: Color IQ™ Optic Enables Full-Color Gamut for Ultra-Thin Displays and All-in-One Computers April 16th, 2015

The National Science Foundation names engineering researcher Andrea Alú its Alan T. Waterman awardee for 2015: Alú is a pioneer in the field of metamaterials who has developed "cloaking" technology to make objects invisible to sensors April 16th, 2015

Graphenea embarks on a new era April 16th, 2015

Display technology/LEDs/SS Lighting/OLEDs

QD Vision Expands Product Line with Two-Millimeter Color LCD Display Optic: Color IQ™ Optic Enables Full-Color Gamut for Ultra-Thin Displays and All-in-One Computers April 16th, 2015

Light in a spin: Researchers demonstrate angular accelerating light April 15th, 2015

Graphene

Graphenea embarks on a new era April 16th, 2015

The Casiraghi Group, located at the University of Manchester's NanoScience and Spectroscopy Laboratory, use Raman in the study of graphene April 14th, 2015

Nanoelectronics

Nanotubes with two walls have singular qualities: Rice University lab calculates unique electronic qualities of double-walled carbon nanotubes April 16th, 2015

Solution-grown nanowires make the best lasers April 14th, 2015

Water makes wires even more nano: Rice University lab extends meniscus-mask process to make sub-10 nanometer paths April 6th, 2015

Demonstration of 50GHz Ge Waveguide Electro-Absorption Modulator April 2nd, 2015

Discoveries

Protein Building Blocks for Nanosystems: Scientists develop method for producing bio-based materials with new properties April 17th, 2015

Major advance in artificial photosynthesis poses win/win for the environment: Berkeley Lab researchers perform solar-powered green chemistry with captured CO2 April 16th, 2015

Newly-Developed Nanocatalysts Increase Performance of Fuel Cells April 16th, 2015

Lanthanide-Organic Framework Nanothermometers Prepared by Spray-Drying April 16th, 2015

Announcements

Protein Building Blocks for Nanosystems: Scientists develop method for producing bio-based materials with new properties April 17th, 2015

Oxford Instruments commissions high field outsert magnet system for the National High Magnetic Field Laboratory 32 Tesla magnet program April 17th, 2015

Newly-Developed Nanocatalysts Increase Performance of Fuel Cells April 16th, 2015

Lanthanide-Organic Framework Nanothermometers Prepared by Spray-Drying April 16th, 2015

Energy

Major advance in artificial photosynthesis poses win/win for the environment: Berkeley Lab researchers perform solar-powered green chemistry with captured CO2 April 16th, 2015

Newly-Developed Nanocatalysts Increase Performance of Fuel Cells April 16th, 2015

Graphenea embarks on a new era April 16th, 2015

Cobalt film a clean-fuel find: Rice University discovery is efficient, robust at drawing hydrogen and oxygen from water April 15th, 2015

Solar/Photovoltaic

The microscopic topography of ink on paper: Researchers have analyzed the varying thickness of printed toner in unprecedented 3-D detail, yielding insights that could lead to higher quality, less expensive and more environmentally-friendly glossy and non-glossy papers April 14th, 2015

Graphene pushes the speed limit of light-to-electricity conversion: Researchers from ICFO, MIT and UC Riverside have been able to develop a graphene-based photodetector capable of converting absorbed light into an electrical voltage at ultrafast timescales April 14th, 2015

Iranian Scientists Use Ultrasound Waves to Produce Fullerene April 9th, 2015

Wrapping carbon nanotubes in polymers enhances their performance: Scientists at Japan's Kyushu University say polymer-wrapped carbon nanotubes hold much promise in biotechnology and energy applications March 30th, 2015

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







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE