Thermally stable and highly efficient red-emitting Eu³⁺-doped Cs₃GdGe₃O₉ phosphors for WLEDs: non-concentration quenching and negative thermal expansion.

ABSTRACT: Red phosphor materials play a key role in improving the lighting and backlit display quality of phosphor-converted white light-emitting diodes (pc-WLEDs). However, the development of a red phosphor with simultaneous high efficiency, excellent thermal stability and high colour purity is still a challenge. In this work, unique non-concentration quenching in solid-solution Cs₃Gd_1?-?xGe₃O₉:xEu³⁺ (CGGO:xEu³⁺) (x?=?0.1-1.0) phosphors is successfully developed to achieve a highly efficient red-emitting Cs₃EuGe₃O₉ (CEGO) phosphor. Under the optimal 464?nm blue light excitation, CEGO shows a strong red emission at 611?nm with a high colour purity of 95.07% and a high internal quantum efficiency of 94%. Impressively, this red-emitting CEGO phosphor exhibits a better thermal stability at higher temperatures (175-250?°C, >90%) than typical red K₂SiF₆:Mn⁴⁺ and Y₂O₃:Eu³⁺ phosphors, and has a remarkable volumetric negative thermal expansion (coefficient of thermal expansion, ??=?-5.06?×?10^-5/°C, 25-250?°C). By employing this red CEGO phosphor, a fabricated pc-WLED emits warm white light with colour coordinates (0.364, 0.383), a high colour rendering index (CRI?=?89.7), and a low colour coordinate temperature (CCT?=?4508?K). These results indicate that this highly efficient red-emitting phosphor has great potential as a red component for pc-WLEDs, opening a new perspective for developing new phosphor materials.

SUBMITTER: Dang P 

PROVIDER: S-EPMC7851390 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature