Featured Research

from universities, journals, and other organizations

Novel nanoparticle production method could lead to better lights, lenses, solar cells

Date:
June 17, 2014
Source:
Sandia National Laboratories
Summary:
Researchers have come up with a way to make titanium-dioxide nanoparticles, which have a variety of uses in everything from solar cells to LEDs. Titanium-dioxide nanoparticles show great promise, but industry has largely shunned them in the past because they’ve been difficult and expensive to make.

Sandia National Laboratories researchers Dale Huber, left, and Todd Monson have come up with an inexpensive way to synthesize titanium-dioxide nanoparticles, which could be used in everything from solar cells to light-emitting diodes.
Credit: Randy Montoya

Sandia National Laboratories has come up with an inexpensive way to synthesize titanium-dioxide nanoparticles and is seeking partners who can demonstrate the process at industrial scale for everything from solar cells to light-emitting diodes (LEDs).

Titanium-dioxide (TiO2) nanoparticles show great promise as fillers to tune the refractive index of anti-reflective coatings on signs and optical encapsulants for LEDs, solar cells and other optical devices. Optical encapsulants are coverings or coatings, usually made of silicone, that protect a device.

Industry has largely shunned TiO2 nanoparticles because they've been difficult and expensive to make, and current methods produce particles that are too large.

Sandia became interested in TiO2 for optical encapsulants because of its work on LED materials for solid-state lighting.

Current production methods for TiO2 often require high-temperature processing or costly surfactants -- molecules that bind to something to make it soluble in another material, like dish soap does with fat.

Those methods produce less-than-ideal nanoparticles that are very expensive, can vary widely in size and show significant particle clumping, called agglomeration.

Sandia's technique, on the other hand, uses readily available, low-cost materials and results in nanoparticles that are small, roughly uniform in size and don't clump.

"We wanted something that was low cost and scalable, and that made particles that were very small," said researcher Todd Monson, who along with principal investigator Dale Huber patented the process in mid-2011 as "High-yield synthesis of brookite TiO2 nanoparticles."

Low-cost technique produces uniform nanoparticles that don't clump

Their method produces nanoparticles roughly 5 nanometers in diameter, approximately 100 times smaller than the wavelength of visible light, so there's little light scattering, Monson said.

"That's the advantage of nanoparticles -- not just nanoparticles, but small nanoparticles," he said.

Scattering decreases the amount of light transmission. Less scattering also can help extract more light, in the case of an LED, or capture more light, in the case of a solar cell.

TiO2 can increase the refractive index of materials, such as silicone in lenses or optical encapsulants. Refractive index is the ability of material to bend light. Eyeglass lenses, for example, have a high refractive index.

Practical nanoparticles must be able to handle different surfactants so they're soluble in a wide range of solvents. Different applications require different solvents for processing.

Technique can be used with different solvents

"If someone wants to use TiO2 nanoparticles in a range of different polymers and applications, it's convenient to have your particles be suspension-stable in a wide range of solvents as well," Monson said. "Some biological applications may require stability in aqueous-based solvents, so it could be very useful to have surfactants available that can make the particles stable in water."

The researchers came up with their synthesis technique by pooling their backgrounds -- Huber's expertise in nanoparticle synthesis and polymer chemistry and Monson's knowledge of materials physics. The work was done under a Laboratory Directed Research and Development project Huber began in 2005.

"The original project goals were to investigate the basic science of nanoparticle dispersions, but when this synthesis was developed near the end of the project, the commercial applications were obvious," Huber said. The researchers subsequently refined the process to make particles easier to manufacture.

Existing synthesis methods for TiO2 particles were too costly and difficult to scale up production. In addition, chemical suppliers ship titanium-dioxide nanoparticles dried and without surfactants, so particles clump together and are impossible to break up. "Then you no longer have the properties you want," Monson said.

The researchers tried various types of alcohol as an inexpensive solvent to see if they could get a common titanium source, titanium isopropoxide, to react with water and alcohol.

The biggest challenge, Monson said, was figuring out how to control the reaction, since adding water to titanium isopropoxide most often results in a fast reaction that produces large chunks of TiO2, rather than nanoparticles. "So the trick was to control the reaction by controlling the addition of water to that reaction," he said.

Textbooks said making nanoparticles couldn't be done, Sandia persisted

Some textbooks dismissed the titanium isopropoxide-water-alcohol method as a way of making TiO2 nanoparticles. Huber and Monson, however, persisted until they discovered how to add water very slowly by putting it into a dilute solution of alcohol. "As we tweaked the synthesis conditions, we were able to synthesize nanoparticles," Monson said.

The next step is to demonstrate synthesis at an industrial scale, which will require a commercial partner. Monson, who presented the work at Sandia's fall Science and Technology Showcase, said Sandia has received inquiries from companies interested in commercializing the technology.

"Here at Sandia we're not set up to produce the particles on a commercial scale," he said. "We want them to pick it up and run with it and start producing these on a wide enough scale to sell to the end user."

Sandia would synthesize a small number of particles, then work with a partner company to form composites and evaluate them to see if they can be used as better encapsulants for LEDs, flexible high-index refraction composites for lenses or solar concentrators. "I think it can meet quite a few needs," Monson said.


Story Source:

The above story is based on materials provided by Sandia National Laboratories. Note: Materials may be edited for content and length.


Cite This Page:

Sandia National Laboratories. "Novel nanoparticle production method could lead to better lights, lenses, solar cells." ScienceDaily. ScienceDaily, 17 June 2014. <www.sciencedaily.com/releases/2014/06/140617111824.htm>.
Sandia National Laboratories. (2014, June 17). Novel nanoparticle production method could lead to better lights, lenses, solar cells. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/2014/06/140617111824.htm
Sandia National Laboratories. "Novel nanoparticle production method could lead to better lights, lenses, solar cells." ScienceDaily. www.sciencedaily.com/releases/2014/06/140617111824.htm (accessed August 1, 2014).

Share This




More Matter & Energy News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
7 Ways to Use Toothpaste: Howdini Hacks

7 Ways to Use Toothpaste: Howdini Hacks

Howdini (July 30, 2014) Fresh breath and clean teeth are great, but have you ever thought, "my toothpaste could be doing more". Well, it can! Lots of things! Howdini has 7 new uses for this household staple. Video provided by Howdini
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins