Rb₃SiF₇:Mn⁴⁺ and Rb₂CsSiF₇:Mn⁴⁺ Red-Emitting Phosphors with a Faster Decay Rate

Abstract

A narrow-band red emission is a seminal issue for establishing the color-rendering index and color gamut of phosphor-converted white light emitting diode (pc-WLED) applications. In this regard, Mn 4+ -activated K 2 SiF 6 phosphors (referred to as K216) have recently attracted a great deal of attention after their successful commercialization. As with K216 phosphors, Mn 4+ -activated K 3 SiF 7 (referred to as K317) phosphors perform in a manner that is similar to that of K216 phosphors and have been introduced as a narrow-band red phosphor. Despite the acceptable performances of both versions of phosphors, slower decay remains a shortcoming for applications to high-powered LEDs. We introduced K317 derivatives by replacing K with Rb and Cs. As a result, Mn 4+ -activated (Rb,Cs) 3 SiF 7 phosphors were synthesized with different Rb:Cs ratios and exhibited faster decay times by comparison with both the K216 and the K317 phosphors. The present study involved both structural and luminescent investigations along with density functional theory (DFT) calculations for novel (Rb,Cs) 3 SiF 7 :Mn 4+ phosphors. This study reveals the possibility of a completely solid solution with single-phase formation within the entire range of Rb−Cs with retention of the tetragonal structure in the P4/mbm space group.

Synthesis, Crystal Structure, and Photoluminescence Characteristics of High-Efficiency Deep-Red Emitting Ba2GdTaO6:Mn4+ Phosphors

“…44,45 Under excitation at 358 nm, the BGT:0.6%Mn 4+ sample exhibited an intense deep-red emission band in the wavelength range of 620–800 nm, with three emission peaks at 662, 674, and 688 nm, which can be assigned to the spin-forbidden 2 E g → 4 A 2g transition of the Mn 4+ ions. 46,47 Among these emission peaks, the 688 nm emission peak showed the strongest intensity. Figure 4b shows the Commission Internationale de l’Éclairage (CIE) diagram of BGT:0.6%Mn 4+ phosphors.…”

Chromium Ion Pair Luminescence: A Strategy in Broadband Near-Infrared Light-Emitting Diode Design

“…Phosphor-converted light-emitting diodes (pc-LEDs) are widely incorporated in everyday applications as a result of their environmental friendliness, low cost, and long life stability. Advancements in solid-state lighting are facilitated by material discovery; using high-throughput approaches, structural design as informed by density functional theory calculations targeting property optimization has already reduced the size of conventional LEDs to micro and mini, enabling the visualization of colors with finer contrast for backlighting applications. − This pc-LED technology also finds use as an alternative light source for still-developing compact NIR applications including spectroscopy, health monitoring, biomodulation, bioimaging, plant growth, night vision, and anticounterfeit identification. − In such NIR devices, NIR-emitting phosphors are encapsulated over blue LEDs, with the final performance almost solely dependent on the phosphors . Accordingly, NIR-emitting luminescence materials with high efficiency and good thermal properties are in increasing demand.…”

Cation Substitution Induced Adjustment on Lattice Structure and Photoluminescence Properties of Mg14Ge5O24:Mn4+: Optimized Emission for w‐LED and Thermometry Applications

“…Given the exposed outer electron in 3d 3 electronic configuration of Mn 4+ ions, its optical property is sensitive to the coordination environment of host matrix . Some previous studies have confirmed that Mn 4+ ions preferentially reside in octahedral crystallographic sites except for several special cases . Many fluoride systems could well satisfy this structural requirement for Mn 4+ ions, and thus they are extensively developed as red‐emitting phosphors in white light‐emitting diodes (w‐LEDs).…”