Full-visible-spectrum lighting realized by a novel Eu2+-doped cyan-emitting borosilicate phosphor

Abstract

White light-emitting diodes (WLEDs) have become one of the first choices in the field of lighting due to their unique advantages. In the traditional system of near-ultraviolet (NUV) chips combined with blue/green/red-emitting phosphors, the partial absence of a blue-green cavity makes it difficult to achieve full-spectrum emission. Accordingly, cyan-emitting phosphors can effectively compensate for this missing part. Therefore, it is necessary and urgent to explore the cyan-emitting phosphor with excellent luminous performance. Herein, we have designed and prepared a novel cyan-emitting borosilicate phosphor Ba₃Ca₄(BO₃)₃(SiO₄)Cl:xEu²⁺ (BCBS:xEu²⁺). Its crystal structure was determined by powder X-ray diffraction and Rietveld methods. The BCBS:xEu²⁺ phosphors have a wide excitation band covering the UV-NUV region and can emit a broad cyan light. The emission peaks at 488 nm have a large full width at half maximum (FWHM) of 118 nm, excited by 350 nm. There are three different Eu²⁺ luminescence centers in BCBS:xEu²⁺, which are determined by analyzing the structure and decay curves. The optimal concentration was x = 0.04 and the quantum efficiency of the BCBS:0.04Eu²⁺ sample was 31.2%. In addition, by combining BCBS:Eu²⁺, Sr₂SiO₄:Eu²⁺ and (Ca,Sr)AlSiN₃:Eu²⁺ phosphors with a 395 nm NUV chip, a WLED lamp was obtained. The emitted white light can display excellent performances of CIE = (0.3655, 0.3641), CCT = 4337 K and CRI = 90.1. All the results demonstrate that the BCBS:Eu²⁺ phosphors have potential applications in full-visible-spectrum lighting.