Long-term stable, low-temperature remote silicate phosphor thick films printed on a glass substrate

Area of Science:

• Materials Science
• Solid-State Lighting
• Phosphor Technology

Background:

• Developing stable, cost-effective phosphors is crucial for white light-emitting diodes (LEDs).
• Current phosphor solutions face limitations in thermal stability and manufacturing complexity.
• Silicate phosphors offer potential due to their inherent stability and low cost.

Purpose of the Study:

• To demonstrate a novel remote-phosphor approach using phosphor-embedded glass thick films.
• To investigate the performance and stability of (Ba,Sr,Ca)₂SiO₄:Eu²⁺ silicate phosphors in a glass matrix.
• To establish a scalable and low-temperature fabrication method for LED phosphors.

Main Methods:

• Fabrication of glass thick films by screen-printing a paste containing (Ba,Sr,Ca)₂SiO₄:Eu²⁺ phosphor and low softening point glass.
• Integration of the phosphor layer onto soda lime silicate glass substrates.
• Characterization of film properties, luminous efficacy, and long-term operational stability.

Main Results:

• Achieved a high luminous efficacy of approximately 32 lm/W at 200 mA using the remote-phosphor approach.
• Demonstrated controllable film thickness and phosphor layer location (top vs. bottom).
• Confirmed long-term luminous efficacy stability exceeding 500 hours of operation.
• Achieved promising densification and adhesion at a low processing temperature of 410 °C.

Conclusions:

• Phosphor-embedded glass thick films offer a viable, cost-effective alternative for white LED applications.
• The developed remote-phosphor structure overcomes limitations of conventional phosphor materials.
• This approach has significant implications for advancing phosphor technology in solid-state lighting.