Broadband emission Gd₃Sc₂Al₃O₁₂:Ce³⁺ transparent ceramics with a high color rendering index for high-power white LEDs/LDs

Area of Science:

• Materials Science
• Solid-State Lighting
• Ceramics Engineering

Background:

• High color rendering index (CRI) is crucial for white light-emitting diodes (LEDs) and laser diodes (LDs).
• Single-structure Ce3+ doped garnet transparent ceramics (TCs) with broad full width at half maximum (FWHM) are essential for achieving high CRI.
• Existing materials may have limitations in FWHM or CRI for high-power applications.

Purpose of the Study:

• To fabricate a pure phase Gadolinium Scandium Aluminum Garnet doped with Cerium (GSAG:Ce) transparent ceramic (TC) with a broad FWHM and high CRI.
• To investigate the optical properties and thermal stability of the fabricated GSAG:Ce TC.
• To demonstrate the application of GSAG:Ce TCs in high-power white LEDs and laser diodes (LDs).

Main Methods:

• Ion substitution engineering strategy was employed.
• Vacuum sintering technique was utilized for fabrication.
• Optical properties (FWHM, transmittance, emission shift, IQE) and thermal stability were characterized.
• Remote excitation white LEDs and LDs were constructed using the fabricated TCs.

Main Results:

• A pure phase GSAG:Ce TC with a broad FWHM of 132.4 nm and a high CRI of 80.7 was fabricated for the first time.
• Optimized in-line transmittance reached 58.4% @ 800 nm.
• A significant red shift in emission from 546 nm to 582 nm was observed, with a high internal quantum efficiency (IQE) of 46.91%.
• Degraded thermal stability was noted compared to Ce:YAG TC due to a narrowed band gap.
• Tunable color hue from yellow to white was achieved in white LEDs.
• White LDs achieved a CRI of 69.5 and a correlated color temperature (CCT) of 7766 K.

Conclusions:

• The study successfully developed a novel GSAG:Ce TC with excellent properties for high-power white lighting.
• This material offers a new pathway for developing high-CRI transparent ceramics for advanced LED and LD applications.
• The findings provide valuable insights for future material design and optimization in solid-state lighting.