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Solid-State Light Converters Optimized for High-Power LED Systems

Materials scientists from Far Eastern Federal University (FEFU) worked with an international team of researchers team to optimize the design of composite ceramic materials (Ce3+:YAG-Al2O3), that is, solid-state light converters (phosphors) that can be employed in-ground and aerospace technologies.

The microstructure of a composite ceramic phosphor, and the appearance of an LED device based on it. Image Credit: Far Eastern Federal University.

The LED system was created based on the developed materials to save 20% to 30% more energy than the commercial equivalents. An article related to this study was published in the Materials Characterization journal.

More than 15% of the entire global production of electricity or around $450 billion is spent on lighting per year. As per the photonics development roadmap run in Russia, the development of LED technology with an efficiency of over 150 lm/W will enable the discharge of up to 30% of electricity by 2025.

With the developed ceramic light converters, both high-power (high brightness) and compact energy-efficient white light-emitting diodes (wLEDs) systems can be produced. The new material is sought-after for several photonic applications right from endoscopes and portable projectors to lighting devices for auto and aircraft construction, laser TVs with a diagonal measuring over 100 inches, megastructures, etc.

The consumption of white LEDs is more than half of the total consumption of high brightness LEDs. Some peculiarities of the technology for the production of organic phosphors for modern commercial white LEDs lead to the quick aging of the light-emitting diode that loses brightness and quality of color rendering.

Anastasia Vornovskikh, Junior Researcher, REC for “Advanced Ceramic Materials,” Polytechnic Institute, Far Eastern Federal University

We get around the problem by creating completely inorganic light converters in the form of composite ceramics based on yttrium aluminum garnet, activated by cerium ions Ce3+:YAG, and a thermally stable phase of aluminum oxide Al2O3,” added Vornovskikh.

The new materials are defined by high values of thermal conductivity and thermal strength, bear high pumping power, and produce bright white light without any evident thermal quenching of the photoluminescence intensity.

This makes it viable to minimize the operating temperature of the LED device down to 120 °C to 70 °C, which is over two times in contrast to commercial samples of Ce3+:YAG.

We synthesized materials by vacuum reactive sintering of initial oxide powders of aluminum, yttrium, cerium, and gadolinium. Particular attention we paid to the identification of the quantitative relationship between the main scattering centers that are residual pores and Al2O3 crystallites and the spectroscopic properties of ceramic phosphors.

Denis Kosyanov, Project Manager and Director, REC for “Advanced Ceramic Materials,” Industrial Safety Department, Polytechnic Institute, Far Eastern Federal University

Our light converters meet all the requirements for new generation wLEDs. They have a long lifespan, high luminous efficacy and color rendering index while maintaining the requirements for the environmental friendliness and material dimensions,” added Kosyanov.

Scientists from Far Eastern Federal University (FEFU); Shanghai Institute of Ceramics, the Shanghai Technological Institute, the University of the Chinese Academy of Sciences; Institute of Chemistry of the Far Eastern Branch of the Russian Academy of Sciences; and Institute of Solid State Chemistry and Mechanochemistry of the Siberian Branch of the Russian Academy of Sciences contributed to the study.

This study was funded by the Russian Science Foundation (Project No. 20-73-10242).

Journal Reference:

Kosyanov, D. Yu., et al. (2021) Al2O3–Ce:YAG and Al2O3–Ce:(Y,Gd)AG composite ceramics for high brightness lighting: Effect of microstructure. Materials Characterization. doi.org/10.1016/j.matchar.2021.110883.

Source: https://www.dvfu.ru/en/

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