Decoding Balanced High-Performance in Fe³⁺ NIR Phosphors via Site-Selectivity for Versatile Applications.

Area of Science:

• Materials Science
• Solid-State Physics
• Photonics

Background:

• Near-infrared (NIR) phosphor-converted LEDs are crucial for photonics, but current chromium (Cr³⁺)-activated materials have performance limitations.
• There is a need for advanced NIR luminescent materials that overcome the drawbacks of existing Cr³⁺-based phosphors.

Purpose of the Study:

• To develop a novel, high-performance, chromium-free NIR phosphor.
• To investigate the potential of iron (Fe³⁺) as an activator in a rigid garnet host for NIR emission.
• To elucidate the fundamental mechanisms governing the luminescence properties.

Main Methods:

• Synthesis and characterization of a novel Fe³⁺-activated garnet phosphor, Ca₃Sn₂Ga₂SiO₁₂:Fe³⁺ (CSGS: Fe³⁺).
• Measurement of photoluminescence properties, including emission spectrum, internal quantum efficiency (IQE), and external quantum efficiency (EQE).
• Thermal stability testing and first-principles calculations to analyze electronic structure, mechanical properties, and luminescence mechanisms.

Main Results:

• Successfully synthesized CSGS: Fe³⁺, exhibiting efficient broadband NIR emission centered at 770 nm (600-1100 nm).
• Achieved high IQE (62.38%) and EQE (46.56%) with remarkable thermal stability (62% intensity retained at 423 K).
• First-principles calculations confirmed the material's properties and proposed a crystal-field-induced site-selective luminescence mechanism.

Conclusions:

• CSGS: Fe³⁺ is a promising Cr-free NIR phosphor with balanced performance exceeding most Fe³⁺-based systems.
• The study provides theoretical insights and practical guidance for designing advanced NIR phosphors for applications in solid-state lighting, nondestructive testing, and spectral analysis.