Ultra-Narrow-Band Blue-Emitting Oxoberyllates AELi2 [Be4 O6 ]:Eu2+ (AE=Sr,Ba) Paving the Way to Efficient RGB pc-LEDs.

Highly efficient phosphor-converted light-emitting diodes (pc-LEDs) are popular in lighting and high-tech electronics applications. The main goals of present LED research are increasing light quality, preserving color point stability and reducing energy consumption. For those purposes excellent phosphors in all spectral regions are required. Here, we report on ultra-narrow band blue emitting oxoberyllates AELi2 [Be4 O6 ]:Eu2+ (AE=Sr,Ba) exhibiting a rigid covalent network isotypic to the nitridoalumosilicate BaLi2 [(Al2 Si2 )N6 ]:Eu2+ . The oxoberyllates' extremely small Stokes shift and unprecedented ultra-narrow band blue emission with fwhm ≈25 nm (≈1200 cm-1 ) at λem =454-456 nm result from its rigid, highly condensed tetrahedra network. AELi2 [Be4 O6 ]:Eu2+ allows for using short-wavelength blue LEDs (λem <440 nm) for efficient excitation of the ultra-narrow band blue phosphor, for application in violet pumped white RGB phosphor LEDs with improved color point stability, excellent color rendering, and high energy efficiency.