Design of Mixed-Anionic-Ligands System for a Blue-Light-Excited Orange-Yellow Emission Phosphor Ba1.31Sr3.69 (BO3)3Cl:Eu2+
The essence of improving the quality of white-light-emitting diodes (w-LEDs) is to explore effective red-emitting phosphor materials. It is well known that the redshift of excitation and emission spectra are related to crystal field splitting (εcfs), centroid shift (εc) and Stokes shift (△S). In this article, the design of mixed-anionic-ligands system with different electronegativity and ion radius is introduced to achieve the redshift of excitation and emission spectra, which can not only effectively improve εcfs, but also have a positive impact on the increase εc and △S. Ba1.31Sr3.69(BO3)3Cl:Eu2+ emerged as a new high-performance orange-yellow-emitting phosphor, which efficiently be excited by blue InGaN chip and exhibit a broad asymmetric band covering from 480 to 750 nm with a peak at 595 nm. Based on density functional theory calculations from first principles, the orange-yellow emission is caused by the Eu 4f electronic structures. Compared with commercially available w-LED phosphor Y3Al5O12:Ce3+ (YAG:Ce3+), more red-emitting component in this phosphor leads to an excellent color rendering index (CRI, Ra = 91) and a lower correlation color temperature (CCT, 4568 K) when employed in a phosphor-converted LED (pc-LED). In addition, a good resistance to thermal quenching is also shown in this material, its integrated intensity at 373 K still maintains ∼86.4% of the one at room temperature. These results indicate that the Ba1.31Sr3.69(BO3)3Cl:Eu2+ phosphor can be a promising candidate for high quality white pc-LEDs.