Bredigite-structure orthosilicate phosphor as a green component for white LED: the structural and optical properties

Area of Science:

• Materials Science
• Solid-State Chemistry
• Luminescence

Background:

• Development of efficient phosphors is critical for advancing white light emitting diode (WLED) technology.
• Europium-activated materials are widely investigated for their luminescent properties.

Purpose of the Study:

• Synthesize and characterize a novel green-emitting phosphor, Ca₁₄-xEuxMg₂[SiO₄]₈ (CMS:Eu²⁺).
• Investigate its potential as a component in WLEDs for high-quality white light generation.

Main Methods:

• Solid-state synthesis of CMS:Eu²⁺ phosphor.
• Photoluminescence spectroscopy to determine emission spectra and excitation wavelengths.
• Analysis of energy transfer mechanisms (dipole-dipole interaction) and critical distance using Dexter's theory.
• Fabrication of WLEDs by incorporating the phosphor with a red phosphor and UV LED.

Main Results:

• CMS:Eu²⁺ exhibits broad green emission with a maximum at ~505 nm under 400 nm excitation, attributed to Eu²⁺ 4f⁶5d → 4f⁷ transition.
• Dipole-dipole interaction is identified as the dominant energy transfer mechanism.
• Calculated critical distances of 12.9 Å and 14.9 Å.
• Achieved white light with a high color rendering index (CRI) of 91 when integrated into WLEDs with a red phosphor and UV LED.

Conclusions:

• CMS:Eu²⁺ is a promising green-emitting phosphor for WLED applications.
• The synthesized phosphor contributes to achieving high-quality white light with excellent color rendering.
• The study provides insights into the luminescence properties and energy transfer mechanisms relevant for phosphor development.