Ab Initio Calculations Driven Discovery of BaLiF 3 :Mn 4+ Fluoride Phosphor with Zero‐Phonon Line Peak at 630.5 nm for Ultrawide Color Gamut Display

Abstract The discovery of Mn 4+ ‐activated fluoride red phosphors with longer emission wavelength is crucial for ultrawide color gamut displays. However, since the emission of Mn 4+ ( 2 E → 4 A 2 ) is constrained by the strong ionic interaction between Mn 4+ and F ‐ , it is a significant challenge to tune the emission to meet the requirement of Recommendation BT.2020 (Rec. 2020) red‐light standard (0.708, 0.292). Herein, density functional theory (DFT) calculations are utilized to determine the 2 E emission energy of Mn 4+ in fluorides; thus, a red phosphor BaLiF 3 :Mn 4+ with a record long‐wavelength zero‐phonon line (ZPL) emission at 630.5 nm and CIE chromaticity coordinates of (0.706, 0.294) is demonstrated. The apparent redshift of the emission of BaLiF 3 :Mn 4+ (ZPL = 630.5 nm) compared to that of commercial K 2 SiF 6 :Mn 4+ (ZPL = 621 nm) is attributed to the high symmetry of the host lattice and the relatively strong electronegativity of the neighboring Li atoms around Mn 4+ . A prototype display device with an ultra‐color gamut of 94.2% Rec.2020 is assembled by using the BaLiF 3 :Mn 4+ based white mini‐LED backlight module. This study not only provides a promising candidate in the field of display, but also provides valuable references for accelerating the discovery of new and promising phosphors.