Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Microwave oven cooks up solar cell material: Nanocrystal semiconductor for photovoltaics, medical sensors, heat reuse

A small, prototype solar cell that uses CZTS, a photovoltaic semiconductor that University of Utah metallurgists produced in an old microwave oven that once heated student lunches.

Credit: Lee J. Siegel, University of Utah.
A small, prototype solar cell that uses CZTS, a photovoltaic semiconductor that University of Utah metallurgists produced in an old microwave oven that once heated student lunches.

Credit: Lee J. Siegel, University of Utah.

Abstract:
University of Utah metallurgists used an old microwave oven to produce a nanocrystal semiconductor rapidly using cheap, abundant and less toxic metals than other semiconductors. They hope it will be used for more efficient photovoltaic solar cells and LED lights, biological sensors and systems to convert waste heat to electricity.

Microwave oven cooks up solar cell material: Nanocrystal semiconductor for photovoltaics, medical sensors, heat reuse

Salt Lake City, UT | Posted on May 6th, 2013

Using microwaves "is a fast way to make these particles that have a broad range of applications," says Michael Free, a professor of metallurgical engineering. "We hope in the next five years there will be some commercial products from this, and we are continuing to pursue applications and improvements. It's a good market, but we don't know exactly where the market will go."

Free and the study's lead author, Prashant Sarswat, a research associate in metallurgical engineering, are publishing their study of the microwaved photovoltaic semiconductor - known as CZTS for copper, zinc, tin and sulfur - in the June 1 issue of the Journal of Crystal Growth.

In the study, they determined the optimum time required to produce the most uniform crystals of the CZTS semiconductor - 18 minutes in the microwave oven - and confirmed the material indeed was CZTS by using a variety of tests, such as X-ray crystallography, electron microscopy, atomic force microscopy and ultraviolet spectroscopy. They also built a small photovoltaic solar cell to confirm that the material works and demonstrate that smaller nanocrystals display "quantum confinement," a property that makes them versatile for different uses.

"It's not an easy material to make," Sarswat says. "There are a lot of unwanted compounds that can form if it is not made properly."

Sarswat says that compared with photovoltaic semiconductors that use highly toxic cadmium and arsenic, ingredients for CZTS photovoltaic material "are more environmentally friendly."

Free adds: "The materials used for this are much lower cost and much more available than alternatives," such as indium and gallium often used in semiconductors.

Making an Old Material More Quickly

Swiss researchers first invented CZTS in 1967 using another method. Other researchers discovered in 1998 that it could serve as a photovoltaic material. But until recently, "people haven't explored this material very much," Sarswat says. CZTS belongs to a family of materials named quaternary chalcogenides.

Without knowing it at first, Free and Sarswat have been in a race to develop the microwave method of making CZTS with a group of researchers at Oregon State University. Sarswat synthesized the material using microwaves in 2011. Free and Sarswat filed an invention disclosure on their method in January 2012, but the other group beat them into print with a study published in August 2012.

The method developed by Sarswat and Free has some unique features, including different "precursor" chemicals (acetate salts instead of chloride salts) used to start the process of making CZTS and a different solvent (oleylamine instead of ethylene glycol.)

Sarswat says many organic compounds are synthesized with microwaves, and Free notes microwaves sometimes are used in metallurgy to extract metal from ore for analysis. They say using microwaves to process materials is fast and often suppresses unwanted chemical "side reactions," resulting in higher yields of the desired materials.

CZTS previously was made using various methods, but many took multiple steps and four to five hours to make a thin film of the material, known technically as a "p-type photovoltaic absorber," which is the active layer in a solar cell to convert sunlight to electricity.

A more recent method known as "colloidal synthesis" - preparing the crystals as a suspension or "colloid" in a liquid by heating the ingredients in a large flask - reduced preparation time to 45 to 90 minutes.

Sarswat decided to try microwave production of CZTS when the University of Utah's Department of Metallurgical Engineering decided to get a new microwave oven for the kitchen where students heat up their lunches and make coffee.

"Our department secretary had a microwave to throw away," so Sarswat says he took it to replace one that had recently burned up during other lab experiments.

"The bottom line is you can use just a simple microwave oven to make the CZTS semiconductor," Free says, adding: "Don't do it at home. You have to be cautious when using these kinds of materials in a microwave."

By controlling how long they microwave the ingredients, the metallurgists could control the size of the resulting nanocrystals and thus their possible uses. Formation of CZTS began after 8 minutes in the microwave, but the researchers found they came out most uniform in size after 18 minutes.

Uses for a Microwaved Semiconductor

To make CZTS, salts of the metals are dissolved in a solvent and then heated in a microwave, forming an "ink" containing suspended CZTS nanocrystals. The "ink" then can be painted onto a surface and combined with other coatings to form a solar cell.

"This [CZTS] is the filling that is the heart of solar cells," says Free. "It is the absorber layer - the active layer - of the solar cell."

He says the easy-to-make CZTS photovoltaic semiconductor can be used in more efficient, multilayer solar cell designs. In addition, CZTS has other potential uses, according to Sarswat and Free:

Theromoelectric conversion of heat to electricity, including waste heat from automobiles and industry, or perhaps heat from the ground to power a military camp.

Biosensors, made by painting the nanocrystal "ink" onto a surface and sensitizing the crystals with an organic molecule that allows them to detect small electrical currents that are created when an enzyme in the body becomes active. These biosensors may play a role in future tests to help diagnose cardiovascular disease, diabetes and kidney disease, Sarswat says.

As circuit components in a wide variety of electronics, include devices to convert heat to electricity.

To use solar energy to break down water to produce hydrogen for fuel cells.

The microwave method produced crystals ranging from 3 nanometers to 20 nanometers in size, and the optimum sought by researchers was between 7 nanometers and 12 nanometers, depending on the intended use for the crystals. A nanometer is one-billionth of a meter, or roughly one 25-millionth of an inch.

Larger crystals of CZTS make a good photovoltaic material. Sarswat says the study also demonstrated that smaller crystals of CZTS - those smaller than 5 nanometers - have what is called "quantum confinement," a change in a material's optical and electronic properties when the crystals becomes sufficiently small.

Quantum confinement means the nanocrystals can be "tuned" to emit light of specific, making such material potentially useful for a wide variety of uses, including more efficient LEDs or light-emitting diodes for lighting. Materials with quantum confinement are versatile because they have a "tunable bandgap," an adjustable amount of energy required to activate a material to emit light or electricity.

####

For more information, please click here

Contacts:
Lee J. Siegel

801-581-8993

University of Utah
Communications 201 Presidents Circle, Room 308
Salt Lake City, Utah 84112-9017
801-581-6773
fax: 801-585-3350

Copyright © University of Utah

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

The George Washington University Opens Science and Engineering Hall, Largest Building of Its Kind in D.C.: Building Represents Significant Investment in Research Programs and Facilities; Commitment to Solve Global Problems, Improve Lives of Millions March 5th, 2015

Anousheh Ansari Wins the National Space Society's Space Pioneer Award for "Service to the Space Community" March 5th, 2015

Enhanced Graphene Components for Next Generation Racing Yacht March 5th, 2015

Get ready for NanoDays! March 5th, 2015

Display technology/LEDs/SS Lighting/OLEDs

Breakthrough in OLED technology March 2nd, 2015

New nanowire structure absorbs light efficiently: Dual-type nanowire arrays can be used in applications such as LEDs and solar cells February 25th, 2015

QD Vision Named Edison Award Finalist for Innovative Color IQ™ Quantum Dot Technology February 23rd, 2015

JunPus launched high-performance thermal grease for LED February 20th, 2015

Nanomedicine

Patent for the Novel Cancer Therapies – Ceramide Nanoliposomes March 4th, 2015

Arrowhead to Present at 2015 Barclays Global Healthcare Conference March 4th, 2015

Democratizing synthetic biology: New method makes research cheaper, faster, and more accessible March 3rd, 2015

Pens filled with high-tech inks for do-it-yourself sensors March 3rd, 2015

Sensors

Experiment and theory unite at last in debate over microbial nanowires: New model and experiments settle debate over metallic-like conductivity of microbial nanowires in bacterium March 4th, 2015

Pens filled with high-tech inks for do-it-yourself sensors March 3rd, 2015

Penn researchers develop new technique for making molybdenum disulfide: Extra control over monolayer material with advantages over graphene February 19th, 2015

Researchers build atomically thin gas and chemical sensors: Sensors made of molybdenum disulfide are small, thin and have a high level of selectivity when detecting gases and chemicals February 19th, 2015

Discoveries

Enhanced Graphene Components for Next Generation Racing Yacht March 5th, 2015

American Chemical Society Presidential Symposia: nanoscience, international chemistry March 5th, 2015

Magnetic vortices in nanodisks reveal information: Researchers from Dresden and Jülich use microwaves to read out information from smallest storage devices March 4th, 2015

CiQUS researchers obtain high-quality perovskites over large areas by a chemical method March 4th, 2015

Announcements

The George Washington University Opens Science and Engineering Hall, Largest Building of Its Kind in D.C.: Building Represents Significant Investment in Research Programs and Facilities; Commitment to Solve Global Problems, Improve Lives of Millions March 5th, 2015

Anousheh Ansari Wins the National Space Society's Space Pioneer Award for "Service to the Space Community" March 5th, 2015

Enhanced Graphene Components for Next Generation Racing Yacht March 5th, 2015

Get ready for NanoDays! March 5th, 2015

Energy

CiQUS researchers obtain high-quality perovskites over large areas by a chemical method March 4th, 2015

UC research partnership explores how to best harness solar power March 2nd, 2015

Learning by eye: Silicon micro-funnels increase the efficiency of solar cells February 25th, 2015

Magnetic nanoparticles enhance performance of solar cells X-ray study points the way to higher energy yields February 25th, 2015

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

New research could lead to more efficient electrical energy storage March 4th, 2015

Energy-generating cloth could replace batteries in wearable devices March 4th, 2015

Glass coating improves battery performance: To improve lithium-sulfur batteries, researchers added glass cage-like coating and graphene oxide March 2nd, 2015

Scientific breakthrough in rechargeable batteries: Researchers from Singapore and Québec Team Up to Develop Next-Generation Materials to Power Electronic Devices and Electric Vehicles February 28th, 2015

Solar/Photovoltaic

UC research partnership explores how to best harness solar power March 2nd, 2015

New nanowire structure absorbs light efficiently: Dual-type nanowire arrays can be used in applications such as LEDs and solar cells February 25th, 2015

Learning by eye: Silicon micro-funnels increase the efficiency of solar cells February 25th, 2015

Magnetic nanoparticles enhance performance of solar cells X-ray study points the way to higher energy yields February 25th, 2015

Quantum nanoscience

Important step towards quantum computing: Metals at atomic scale March 2nd, 2015

Quantum many-body systems on the way back to equilibrium: Advances in experimental and theoretical physics enable a deeper understanding of the dynamics and properties of quantum many-body systems February 25th, 2015

Quantum research past, present and future for discussion at AAAS February 16th, 2015

Exotic states materialize with supercomputers February 12th, 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