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Titanium-dioxide (TiO2) nanoparticles show great promise as fillers to tune the refractive index of anti-reflective coatings on signs and optical encapsulants (protective coverings or coatings) for light-emitting diodes (LEDs), solar cells and other optical devices.
Industry has shunned TiO2 nanoparticles because they have been difficult and expensive to make, and current methods produce particles that are too large. Current TiO2 production methods also 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 (in water).
Sandia became interested in TiO2 for optical encapsulants because of its work on LED materials for solid-state lighting. Researchers Dale Huber (in Sandia’s Nanosystems Synthesis/Analysis Dept.) and Todd Monson (in Sandia’s Nanoscale Sciences Dept.) have come up with an inexpensive way to synthesize the TiO2 nanoparticles and are seeking partners to demonstrate the process at industrial scale.
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 Sandia technique uses readily available, low-cost materials and results in nanoparticles that are ~5 nm in diameter, roughly uniform in size, and don’t clump.
“That’s the advantage of nanoparticles—not just nanoparticles, but small nanoparticles,” Monson said. “We wanted something that was low cost and scalable, and made particles that were very small,” he said. Monson and Principal Investigator Huber patented the process as “High-yield synthesis of brookite TiO2 nanoparticles.”
Their process yields particles approximately 100 times smaller than visible-light wavelengths, so there’s little light scattering—helping to extract more light, in the case of an LED, or capture more light, in the case of a solar cell.
Read the Sandia news release.