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.
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 (strontium, lithium, aluminum and oxygen); it can be made using industrial methods; and it produces LEDs that render colors more vividly and accurately.
The new phosphor, Sr2LiAlO4 or simply 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.
The Latest on: Predicting new materials
- Global SaaS Mortgage Software market detailed in new research report on November 12, 2018 at 3:08 pm
Industry key factors, such as sellers and buyers help to predict the success of businesses.It focuses ... investments have been calculated by considering manufacturing base, raw materials as well as t... […]
- Current Research and Future Scope of Materials Science and Nanotechnology on November 12, 2018 at 11:21 am
... transits gradually into a more systems-based approach to materials innovation and toward materials design through which researchers are able to predict new materials they desire rather than having ... […]
- Seed grant allows for new research internship opportunities in applied physics on November 12, 2018 at 11:13 am
The project seeks to understand, predict, and control plasma processes and interactions in low-temperature plasma (LTP) environments. This knowledge can be used to develop new technologies for aerospa... […]
- 3 Smokin’ Hot Stocks Hitting New 52-Week Highs on November 12, 2018 at 9:30 am
Real estate returns Leading things off is Morguard North American REIT(TSX:MRG.UN), whose shares hit a new 52-week high of $17.49 late last week. Year to date, the residential REIT is up 15% versus a ... […]
- Product Expansion to Aid Applied Materials (AMAT) Q4 Earnings on November 12, 2018 at 6:09 am
New display technologies such as OLED are opening new market opportunities for Applied Materials ... making surprise prediction difficult. We see a likely earnings beat for each of the following ... […]
- Apple Will Launch Three iPhones In 2019 With Brand New Antennas on November 12, 2018 at 5:32 am
“We predict that  new iPhone models ... as the material behaves uniformly across all frequencies. The new material will also improve performance for the new smartphones in other areas ... […]
- Kuo: 2019 iPhones to Adopt New MPI Antenna Technology, Combined With Existing LCP Components on November 12, 2018 at 5:14 am
As we enter the era of 5G, Kuo estimates that both MPI and LCP "will coexist" during the transition to the new wireless communications standard. While the market is reportedly confident that the comin... […]
- Charleston's port, rest of maritime industry, braces for new fuel rule on November 11, 2018 at 4:05 pm
For example, fewer than 1-out-of-10 U.S. consumers would pay 10 percent more for a mobile phone to help shipping lines meet the new regulations. Philip Verleger, an analyst with Denver-based PKVerlege... […]
- Polyurethane (PU) Dispersions Market Global Analysis and Prediction by Leading Manufacturers, its Application and Types on November 11, 2018 at 11:46 am
The report right off the bat presented the Polyurethane (PU) Dispersions Market fundamentals: definitions, orders, applications and market review; item determinations; fabricating forms; cost structur... […]
- New materials could allow autonomous vehicles see through rain and fog on November 11, 2018 at 3:46 am
To see through hazardous conditions, sensors within the cars need technology that can predict obstacles ... Engineering and Materials Science at USC Viterbi, wants to develop new electronic ... […]
via Google News and Bing News