Higher chromatic rendition with Cr3+-doped yellow Y3Al5O12:Ce3+ for double-layer remote phosphor white-light-emitting diodes

Abstract

Remote phosphor designs of white-light-emitting diodes (WLEDs) have been recognized for their high thermal stability and excellent luminous efficiency but not for the chromatic rendering. The study presents an approach for the remote phosphor structure to overcome the low-color-rendering issue by enriching its red-light spectral intensity through co-doping Cr³⁺ and Ce³⁺ ions into the yellow  Y₃Al₅O₁₂ (YAG) phosphor compound. This ion co-doping process probably enhances emission spectra in the far-red range because of the energy transfer of the integrated ions: Ce³⁺ Cr³⁺. Additionally, the luminescence and color properties of the phosphor layer significantly depend on the doped concentration of the Cr³⁺ ion. Here, with 0.008% Cr³⁺ in the phosphor composite, either internal or external quantum performances of the dual-layer WLED light are enhanced, which achieved the number of 58.9% and 46.7%, respectively. The color rendering index (CRI) would also be higher if Cr³⁺ is added, about 77.9, compared to the CRI of 63.2 when using the original  YAG:Ce³⁺ phosphor layer.