Nanotechnology Now

Our NanoNews Digest Sponsors


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

Texas A&M Chemist Says Trapped Electrons To Blame For Lack Of Battery Efficiency: Forget mousetraps — today’s scientists will get the cheese if they manage to build a better battery June 28th, 2016

Building a smart cardiac patch: 'Bionic' cardiac patch could one day monitor and respond to cardiac problems June 28th, 2016

New, better way to build circuits for world's first useful quantum computers June 28th, 2016

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Display technology/LEDs/SS Lighting/OLEDs

GraphExeter illuminates bright new future for flexible lighting devices June 23rd, 2016

New nanomaterial offers promise in bendable, wearable electronic devices: Electroplated polymer makes transparent, highly conductive, ultrathin film June 13th, 2016

Graphene-based transparent electrodes for highly efficient flexible OLEDS: A Korean research team developed an ideal electrode structure composed of graphene and layers of titanium dioxide and conducting polymers, resulting in highly flexible and efficient OLEDs June 5th, 2016

Nanotubes are beacons in cancer-imaging technique: Rice University researchers use spectral triangulation to pinpoint location of tumors May 21st, 2016

Nanomedicine

Building a smart cardiac patch: 'Bionic' cardiac patch could one day monitor and respond to cardiac problems June 28th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Nanotechnology and math deliver two-in-one punch for cancer therapy resistance June 24th, 2016

Self-assembling icosahedral protein designed: Self-assembling icosahedral protein designed June 22nd, 2016

Sensors

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

Artificial synapse rivals biological ones in energy consumption June 21st, 2016

A new form of hybrid photodetectors with quantum dots and graphene June 19th, 2016

Drum beats from a one atom thick graphite membrane June 15th, 2016

Discoveries

Texas A&M Chemist Says Trapped Electrons To Blame For Lack Of Battery Efficiency: Forget mousetraps — today’s scientists will get the cheese if they manage to build a better battery June 28th, 2016

Building a smart cardiac patch: 'Bionic' cardiac patch could one day monitor and respond to cardiac problems June 28th, 2016

New, better way to build circuits for world's first useful quantum computers June 28th, 2016

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Announcements

Texas A&M Chemist Says Trapped Electrons To Blame For Lack Of Battery Efficiency: Forget mousetraps — today’s scientists will get the cheese if they manage to build a better battery June 28th, 2016

Building a smart cardiac patch: 'Bionic' cardiac patch could one day monitor and respond to cardiac problems June 28th, 2016

New, better way to build circuits for world's first useful quantum computers June 28th, 2016

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Energy

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

Researchers discover new chemical sensing technique: Technique allows sharper detail -- and more information -- with near infrared light June 24th, 2016

FEI and University of Liverpool Announce QEMSCAN Research Initiative: University of Liverpool will utilize FEI’s QEMSCAN technology to gain a better insight into oil and gas reserves & potentially change the approach to evaluating them June 22nd, 2016

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

Texas A&M Chemist Says Trapped Electrons To Blame For Lack Of Battery Efficiency: Forget mousetraps — today’s scientists will get the cheese if they manage to build a better battery June 28th, 2016

Yale researchers’ technology turns wasted heat into power June 27th, 2016

Stanford researchers find new ways to make clean hydrogen and rechargable zinc batteries June 18th, 2016

Efficient hydrogen production made easy: Sticking electrons to a semiconductor with hydrazine creates an electrocatalyst June 17th, 2016

Solar/Photovoltaic

Nanoscientists develop the 'ultimate discovery tool': Rapid discovery power is similar to what gene chips offer biology June 25th, 2016

New generation of high-efficiency solar thermal absorbers developed June 20th, 2016

Novel capping strategy improves stability of perovskite nanocrystals: Study addresses instability issues with organometal-halide perovskites, a promising class of materials for solar cells, LEDs, and other applications June 13th, 2016

Perovskite solar cells surpass 20 percent efficiency: EPFL researchers are pushing the limits of perovskite solar cell performance by exploring the best way to grow these crystals June 13th, 2016

Quantum nanoscience

CWRU physicists deploy magnetic vortex to control electron spin: Potential technology for quantum computing, keener sensors June 21st, 2016

Neutrons reveal unexpected magnetism in rare-earth alloy June 16th, 2016

Spintronics: Resetting the future of heat assisted magnetic recording June 15th, 2016

NIST's super quantum simulator 'entangles' hundreds of ions June 11th, 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