Thermally stable novel double perovskite orange-red emitting Sr2InTaO6:Sm3+ phosphors with high CRI for WLEDs

Novel double perovskite Sr2InTaO6:Sm3+ phosphors were synthesized by the high-temperature solid-state reaction. The phase purity, luminescent properties, and thermal stability were systematically investigated in this work. When monitoring the emission peak at 649 nm, Sr2InTaO6:Sm3+ phosphors present an absorption band due to the O2−→Sm3+ charge transfer. Under 407 nm excitation, Sr2InTaO6:5 mol%Sm3+ phosphor presents four emission peaks at 565, 603, 649, and 717 nm corresponding to the electron transition from 6G5/2 level to 6H5/2, 6H7/2, 6H9/2 and 6H11/2 levels, respectively. The best doping concentration of Sr2InTaO6:xSm3+ is optimized as x = 5 mol%. The chromaticity coordinates of Sr2InTaO6:xSm3+ show high color stability and are located in the orange-red region. The residual luminescence intensity at 480 K reaches 86.64%, proving it has excellent thermal stability. Internal quantum efficiency (IQE) is measured as 67.1%. The prepared WLED (white light emitting diode) has a low correlation color temperature (CCT = 4853 K) and an excellent color rendering index (CRI, Ra = 93) with CIE (Commission International de L′ Eclairage) coordinates (0.346, 0.349). Therefore, Sr2InTaO6:Sm3+ phosphors have excellent luminescent properties and promising application prospects.