Defect Regulation Induced Luminescence Improvement of the Broadband Orange Phosphor Lu2CaMg2Si3O12:Ce3+ for WLED

Abstract

Phosphors for white light emitting diode (WLED) have been attracting the attention of researchers to obtain devices with a high color rendering index (CRI) and low correlated color temperature (CCT). Herein, the broadband orange phosphor Lu₂CaMg₂Si₃O₁₂:Ce³⁺ is prepared, and Lu³⁺ vacancy is created in the lattice to regulate the structure of this phosphor. This orange phosphor can be excited well by blue light and emit orange light ranging from 500 to 750 nm. By decreasing Lu³⁺ content in the lattice, the band gap of the matrix is widened. Besides, the emission of Ce³⁺ in this garnet structure is improved, and the emission of Lu_1.84CaMg₂Si₃O₁₂:Ce³⁺ reached the maximum of all the samples. The thermal stability of this orange phosphor is improved, and the emission of the phosphor Lu_1.84CaMg₂Si₃O₁₂:Ce³⁺ maintains 75.5% at 423 K compared to that at 298 K. WLED device is fabricated via coating the mixtures of Lu_1.84CaMg₂Si₃O₁₂:Ce³⁺ and the cyan phosphor Ca₃Sc₂Si₃O₁₂:Ce³⁺ onto the blue chip. This WLED device shows a high CRI of 87.9 and a low CCT of 4167 K, verifying the great potential of this orange phosphor in WLED.