Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > Computers aid discovery of new, inexpensive material to make LEDs with high color quality

Under UV light, the phosphor emits either green-yellow or blue light depending on the chemical activator mixed in. Photos by David Baillot/UC San Diego Jacobs School of Engineering
Under UV light, the phosphor emits either green-yellow or blue light depending on the chemical activator mixed in. Photos by David Baillot/UC San Diego Jacobs School of Engineering

Abstract:
A team led by engineers at the University of California San Diego has used data mining and computational tools to discover a new phosphor material for white LEDs that is inexpensive and easy to make. Researchers built prototype white LED light bulbs using the new phosphor. The prototypes exhibited better color quality than many commercial LEDs currently on the market.

Computers aid discovery of new, inexpensive material to make LEDs with high color quality

San Diego, CA | Posted on February 20th, 2018

Researchers published the new phosphor on Feb. 19 in the journal Joule.

Phosphors, which are substances that emit light, are one of the key ingredients to make white LEDs. They are crystalline powders that absorb energy from blue or near-UV light and emit light in the visible spectrum. The combination of the different colored light creates white light.

The phosphors used in many commercial white LEDs have several disadvantages, however. Many are made of rare-earth elements, which are expensive, and some are difficult to manufacture. They also produce LEDs with poor color quality.

Researchers at UC San Diego and Chonnam National University in Korea discovered and developed a new phosphor that avoids these issues. It is made mostly of earth-abundant elements; it can be made using industrial methods; and it produces LEDs that render colors more vividly and accurately.

The new phosphor--made of the elements strontium, lithium, aluminum and oxygen (a combination dubbed "SLAO")--was discovered using a systematic, high-throughput computational approach developed in the lab of Shyue Ping Ong, a nanoengineering professor at the UC San Diego Jacobs School of Engineering and lead principal investigator of the study. Ong's team used supercomputers to predict SLAO, which is the first known material made of the elements strontium, lithium, aluminum and oxygen. Calculations also predicted this material would be stable and perform well as an LED phosphor. For example, it was predicted to absorb light in the near-UV and blue region and have high photoluminescence, which is the material's ability to emit light when excited by a higher energy light source.

Researchers in the lab of Joanna McKittrick, a materials science professor at the Jacobs School of Engineering, then figured out the recipe needed to make the new phosphor. They also confirmed the phosphor's predicted light absorption and emission properties in the lab.

A team led by materials science professor Won Bin Im at Chonnam National University in Korea optimized the phosphor recipe for industrial manufacturing and built white LED prototypes with the new phosphor. They evaluated the LEDs using the Color Rendering Index (CRI), a scale that rates from 0 to 100 how accurate colors appear under a light source. Many commercial LEDs have CRI values at around 80. LEDs made with the new phosphor yielded CRI values greater than 90.

The computational quest for a new material

Thanks to the computational approach developed by Ong's team, discovery of the phosphor took just three months--a short time frame compared to the years of trial-and-error experiments it typically takes to discover a new material.

"Calculations are quick, scalable and cheap. Using computers, we can rapidly screen thousands of materials and predict candidates for new materials that have not yet been discovered," Ong said.

Ong, who leads the Materials Virtual Lab and is a faculty member in the Sustainable Power and Energy Center at UC San Diego, uses a combination of high-throughput calculations and machine learning to discover next-generation materials for energy applications, including batteries, fuel cells and LEDs. The calculations were performed using the National Science Foundation's Extreme Science and Engineering Discovery Environment at the San Diego Supercomputer Center.

In this study, Ong's team first compiled a list of the most frequently occurring elements in known phosphor materials. To the researchers' surprise, they found that there are no known materials containing a combination of strontium, lithium, aluminum and oxygen, which are four common phosphor elements. Using a data mining algorithm, they created new phosphor candidates containing these elements and performed a series of first-principles calculations to predict which would perform well as a phosphor. Out of 918 candidates, SLAO emerged as the leading material. It was predicted to be stable and exhibit excellent photoluminescence properties.

"It's not only remarkable that we were able to predict a new phosphor compound, but one that's stable and can actually be synthesized in the lab," said Zhenbin Wang, a nanoengineering Ph.D. candidate in Ong's research group and co-first author of the study.

The phosphor's main limitation is its less than ideal quantum efficiency--how efficiently it converts incoming light to light of a different color--of about 32 percent. However, researchers note that it retains more than 88 percent of its emission at typical LED operating temperatures. In commercial LEDs, there's usually a tradeoff with color quality, Ong noted. "But we want the best of both worlds. We have achieved excellent color quality. Now we are working on optimizing the material to improve quantum efficiency," Ong said.

This work was supported by the National Science Foundation, Ceramics Program (grant 1411192). Computational resources were provided by the Triton Shared Computing Cluster at UC San Diego, the

National Energy Research Scientific Computing Centre, and the Extreme Science and Engineering Discovery Environment supported by the National Science Foundation (grant ACI-1053575). This work was also supported by the Basic Science Research Program through the National Research Foundation of Korea, which is funded by the Ministry of Science and ICT (NRF-2017R1A2B3011967).

####

For more information, please click here

Contacts:
Liezel Labios

858-246-1124

Copyright © University of California - San Diego

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 Links

Paper title: "Mining Unexplored Chemistries for Phosphors for High-Color-Quality White-Light-Emitting Diodes." Authors of the study are Zhenbin Wang*, Jungmin Ha*, Joanna McKittrick and Shyue Ping Ong at UC San Diego; and Yoon Hwa Kim* and Won Bin Im at Chonnam National University, Republic of Korea.

Related News Press

News and information

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Display technology/LEDs/SS Lighting/OLEDs

Exotic spiraling electrons discovered by physicists: Rutgers-led research could lead to advances in lighting and solar cells February 18th, 2019

Molecular Lego blocks: Chemical data mining boosts search for new organic semiconductors February 15th, 2019

CEA-Leti Combines Integrated Optics and Holography In Novel Lens-Free, Augmented Reality Technology: Approach Eliminates the Need for Optical Systems and Combiners in AR; Will Be Presented at SPIE Photonics West 2019 February 6th, 2019

Oxford Instruments Supplies ITRI with Plasma Etch Solutions for MicroLED Development January 22nd, 2019

Govt.-Legislation/Regulation/Funding/Policy

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Researchers reverse the flow of time on IBM's quantum computer March 14th, 2019

When semiconductors stick together, materials go quantum: A new study led by Berkeley Lab reveals how aligned layers of atomically thin semiconductors can yield an exotic new quantum material March 12th, 2019

Arrowhead Pharmaceuticals Begins Dosing in Phase 1 Study of ARO-APOC3 for Treatment of Hypertriglyceridemia March 11th, 2019

Possible Futures

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Discoveries

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Announcements

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Exotic “second sound” phenomenon observed in pencil lead: At relatively balmy temperatures, heat behaves like sound when moving through graphite, study reports March 15th, 2019

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

New method to reduce uranium concentration in contaminated water March 18th, 2019

Review of the recent advances of 2D nanomaterials in Lit-ion batteries March 15th, 2019

Converting biomass by applying mechanical force Nanoscientists discover new mechanism to cleave cellulose effectively and in an environmentally friendly way March 15th, 2019

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Quantum sensing method measures minuscule magnetic fields: MIT researchers find a new way to make nanoscale measurements of fields in more than one dimension March 15th, 2019

Researchers reverse the flow of time on IBM's quantum computer March 14th, 2019

Pushing Past Limits: Junkai Jiang receives prestigious Ph.D. Student Fellowship from IEEE Electron Devices Society March 14th, 2019

When semiconductors stick together, materials go quantum: A new study led by Berkeley Lab reveals how aligned layers of atomically thin semiconductors can yield an exotic new quantum material March 12th, 2019

Research partnerships

Lightweight metal foams become bone hard and explosion proof after being nanocoated March 14th, 2019

When semiconductors stick together, materials go quantum: A new study led by Berkeley Lab reveals how aligned layers of atomically thin semiconductors can yield an exotic new quantum material March 12th, 2019

AIM Photonics Attends OFC 2019—the Optical Networking and Communication Conference & Exhibition to Share World-Class Capabilities and Partnership Opportunity Updates February 28th, 2019

CEA-Leti Breakthrough Opens Path to New Vaccine for HIV: Lipidots Platform Strengthens Immune Response to Protein That Is Key to HIV Vaccine; Results Presented in Nature Publishing Group’s npj Vaccines February 27th, 2019

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project