Full-Visible-Spectrum White LEDs Enabled by a Blue-Light-Excitable Cyan Phosphor

Area of Science:

• Materials Science
• Solid-State Lighting
• Luminescence

Background:

• White light-emitting diodes (WLEDs) require efficient phosphors for full-spectrum emission.
• A critical challenge is the
• cyan gap
• in the 480-520 nm region, hindering ultrahigh color rendering (Ra > 95).
• Existing phosphors struggle to provide sufficient cyan emission to bridge this gap.

Purpose of the Study:

• To synthesize and characterize a novel cyan-emitting phosphor capable of closing the
• cyan gap
• for advanced WLEDs.
• To evaluate the photoluminescence properties, quantum efficiency, and thermal stability of the new phosphor.
• To fabricate and assess a WLED device utilizing the developed phosphor.

Main Methods:

• Synthesis of the garnet phosphor Ca₂LuAlGa₂Si₂O₁₂:Ce³⁺ (CLAGSO:Ce³⁺).
• Photoluminescence spectroscopy under 430 nm excitation to analyze emission spectra and bandwidth.
• Measurement of internal quantum efficiency and thermal quenching performance.
• Fabrication and characterization of a WLED device using the optimal CLAGSO:Ce³⁺ phosphor.

Main Results:

• The optimal CLAGSO:5%Ce³⁺ phosphor exhibited broadband cyan emission (peak at 496 nm, 102 nm bandwidth).
• Achieved a high internal quantum efficiency of 85.6% and good thermal stability (69.1% at 423 K).
• A WLED device demonstrated an ultrahigh color rendering index (Ra = 96.6) and luminous efficacy (74.09 lm W^-1).

Conclusions:

• The developed CLAGSO:Ce³⁺ phosphor effectively bridges the
• cyan gap
• between blue LED chips and commercial yellow phosphors.
• This advancement enables the creation of human-centric, full-visible-spectrum warm WLEDs with superior color quality.
• Highlights the significance of blue-excited broadband cyan emitters for high-performance solid-state lighting applications.