High recorded color rendering index in single Ce,(Pr,Mn):YAG transparent ceramics for high-power white LEDs/LDs

Abstract

Transparent ceramics (TCs) are incredibly promising color converters for high-power white LEDs/LDs. However, the preparation process of multiple structured TCs with a high color rendering index (CRI) is a complicated technical challenge, and the inability of single-structured TCs to achieve a high CRI significantly limits their real applications. In this study, high quality single-structured Ce,(Pr,Mn):YAG TCs with “wide peak” and “narrow peak” red light emissions were designed and fabricated via a solid-state reaction and a vacuum sintering method. Compared with the emission spectra of Ce:YAG TC, the synchronous doping of Pr³⁺ and Mn²⁺ ions into Ce:YAG TC resulted in inhomogeneous broadening of the full width at half maximum (FWHM) from 91.7 nm to 102.2 nm. Impressively, the CRI of a single Ce,(Pr,Mn):YAG TC-based high-power white LED was as high as 84.8, and the correlated-color temperatures (CCTs) of the white LEDs/LDs were 5450 K and 3550 K, respectively. Furthermore, when the addition amounts of Pr³⁺ and Mn²⁺ were 0.2 at% and 0.8 at%, respectively, the as-prepared Ce,(Pr,Mn):YAG TC displayed a high quantum efficiency (IQE = 48.14%) and excellent color stability (only 5% fluctuation). Therefore, this study not only demonstrates how to overcome the spectrum deficiencies of single-structured TCs that restrain intrinsic CRI improvement, but also provides a reference for the pursuit of high luminescence properties. This work significantly reinforces the understanding of the CRI problems of TC-based high-power lighting, which is crucial for the real application of white LEDs/LDs.