Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Particle Works creates range of high performance quantum dots February 23rd, 2017

GLOBALFOUNDRIES Announces Availability of 45nm RF SOI to Advance 5G Mobile Communications: Optimized RF features deliver high-performance solutions for mmWave beam forming applications in 5G smartphones and base stations February 22nd, 2017

EmTech Asia breaks new barriers with potential applications of space exploration with NASA and MIT February 22nd, 2017

JPK selects compact tensile stage from Deben for their NanoWizard® AFM platform to broaden capabilities for materials characterisation February 22nd, 2017

Display technology/LEDs/SS Lighting/OLEDs

Research opens door to smaller, cheaper, more agile communications tech February 16th, 2017

Dual-function nanorod LEDs could make multifunctional displays February 11th, 2017

1,000 times more efficient nano-LED opens door to faster microchips February 5th, 2017

Leti Presents First Results in LED Pixelization & Record Resolution for Micro-Displays at Photonics West February 3rd, 2017

Nanomedicine

Nominations Invited for $250,000 Kabiller Prize in Nanoscience: Major international prize recognizes a visionary nanotechnology researcher February 20th, 2017

Good vibrations help reveal molecular details: Rice University scientists combine disciplines to pinpoint small structures in unlabeled molecules February 15th, 2017

In-cell molecular sieve from protein crystal February 14th, 2017

Cedars-Sinai, UCLA Scientists Use New ‘Blood Biopsies’ With Experimental Device to Speed Cancer Diagnosis and Predict Disease Spread: Leading-Edge Research Is Part of National Cancer Moonshot Initiative February 13th, 2017

Sensors

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Liquid metal nano printing set to revolutionize electronics: Creating integrated circuits just atoms thick February 18th, 2017

Research opens door to smaller, cheaper, more agile communications tech February 16th, 2017

Metamaterial: Mail armor inspires physicists: KIT researchers reverse hall coefficient -- medieval mail armor inspired development of metamaterial with novel properties February 15th, 2017

Discoveries

Molecular phenomenon discovered by advanced NMR facility: Cutting edge technology has shown a molecule self-assembling into different forms when passing between solution state to solid state, and back again - a curious phenomenon in science - says research by the University of Wa February 22nd, 2017

Tiny nanoclusters could solve big problems for lithium-ion batteries February 21st, 2017

Oxford Instruments announces Dr Brad Ramshaw of Cornell University, as winner of the 2017 Lee Osheroff Richardson Science Prize February 20th, 2017

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

Announcements

Particle Works creates range of high performance quantum dots February 23rd, 2017

GLOBALFOUNDRIES Announces Availability of 45nm RF SOI to Advance 5G Mobile Communications: Optimized RF features deliver high-performance solutions for mmWave beam forming applications in 5G smartphones and base stations February 22nd, 2017

EmTech Asia breaks new barriers with potential applications of space exploration with NASA and MIT February 22nd, 2017

JPK selects compact tensile stage from Deben for their NanoWizard® AFM platform to broaden capabilities for materials characterisation February 22nd, 2017

Energy

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

In-cell molecular sieve from protein crystal February 14th, 2017

NREL research pinpoints promise of polycrystalline perovskites February 8th, 2017

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

Tiny nanoclusters could solve big problems for lithium-ion batteries February 21st, 2017

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

Researchers optimize the assembly of micro-/meso-/macroporous carbon for Li-S batteries February 13th, 2017

Solar/Photovoltaic

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

Material can turn sunlight, heat and movement into electricity -- all at once: Extracting energy from multiple sources could help power wearable technology February 9th, 2017

NREL research pinpoints promise of polycrystalline perovskites February 8th, 2017

Quantum nanoscience

The speed limit for intra-chip communications in microprocessors of the future January 23rd, 2017

First experimental proof of a 70 year old physics theory: First observation of magnetic phase transition in 2-D materials, as predicted by the Nobel winner Onsager in 1943 January 6th, 2017

Quantum simulation technique yields topological soliton state in SSH model January 3rd, 2017

Diamonds are technologists' best friends: Researchers from the Lomonosov Moscow State University have grown needle- and thread-like diamonds and studied their useful properties December 30th, 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