A Novel Red-Emitting Na2NbOF5:Mn4+ Phosphor with Ultrahigh Color Purity for Warm White Lighting and Wide-Gamut Backlight Displays.

Jingshan Hou,Guoying Zhao,Ganghua Zhang,Yongzheng Fang,Yufeng Liu,Yang Li,Wenxiang Yin,Langping Dong,Zhifu Liu

doi:10.3390/ma14185317

Abstract

In this work, a novel red-emitting oxyfluoride phosphor Na2NbOF5:Mn4+ with an ultra-intense zero-phonon line (ZPL) was successfully synthesized by hydrothermal method. The phase composition and luminescent properties of Na2NbOF5:Mn4+ were studied in detail. The photoluminescence excitation spectrum contains two intense excitation bands centered at 369 and 470 nm, which match well with commercial UV and blue light-emitting diode (LED) chips. When excited by 470 nm blue light, Na2NbOF5:Mn4+ exhibits red light emission dominated by ZPL. Notably, the color purity of the Na2NbOF5:Mn4+ red phosphor can reach 99.9%. Meanwhile, the Na2NbOF5:Mn4+ phosphor has a shorter fluorescence decay time than commercial K2SiF6:Mn4+, which is conducive to fast switching of images in display applications. Profiting from the intense ZPL, white light-emitting diode (WLED) with high color rendering index of Ra = 86.2 and low correlated color temperature of Tc = 3133 K is realized using yellow YAG:Ce3+ and red Na2NbOF5:Mn4+ phosphor. The WLED fabricated using CsPbBr3 quantum dots (QDs) and red Na2NbOF5:Mn4+ phosphor shows a wide color gamut of 127.56% NTSC (National Television Standard Committee). The results show that red-emitting Na2NbOF5:Mn4+ phosphor has potential application prospects in WLED lighting and display backlight.

Highlights

High luminescence efficiency, environmentally friendly features and long operating lifetimes are all advantageous performance aspects of white light-emitting diodes (WLEDs), which have obtained widespread attention
All the diffraction peaks of the samples matched with the Na2 NbOF5 standard card (ICSD-48165, space group Pcnb (60), a = 5.089(1) Å, b = 5.512(1) Å, c = 18.207(4) Å, cell volume V = 510.72(18) Å3 ) and no impurity phase was found
The color gamut of the produced WLED device is shown in the black frame in Figure 8B, which is calculated as 127.56% of the National Television Standards Committee (NTSC) color gamut and overlaps with NTSC by 99.46%

Summary

Introduction

Environmentally friendly features and long operating lifetimes are all advantageous performance aspects of white light-emitting diodes (WLEDs), which have obtained widespread attention. Phosphor for LED backlight should possess a broad excitation band appropriate to LED chip emission and narrow band emission with high color purity, and have appropriate decay time [13]. The exploration of novel red-emitting phosphors with high color purity and short fluorescence lifetime for backlight displays is necessary. We synthesized a novel red-emitting oxyfluoride phosphor Na2 NbOF5 :Mn4+ for the first time and systematically investigated its crystal structure, composition and PL properties. White LED for indoor lighting and backlight displays was packaged by employing the as-prepared Na2 NbOF5 :Mn4+ phosphor as a red supplement

Sample Preparation

Characterization

X-ray Diffraction and Structure Analysis

Morphology

Conclusions