Review—Temperature Dependence of Transition-Metal and Rare-Earth Ion Luminescence (Mn⁴⁺, Cr³⁺, Mn²⁺, Eu²⁺, Eu³⁺, Tb³⁺, etc.) I: Fundamental Principles

Abstract

Thermal stability of the phosphor materials is of crucial importance and scientific interest. Various Mn4+-activated fluoride, oxide, and oxyfluoride phosphors show an anomalous thermal quenching (TQ) behavior, i.e., no decrease or an increase in the integrated photoluminescence intensity I PL with increasing temperature T, known as zero or negative TQ. The purpose of this article is to discuss such anomalous behaviors of thermal stability of the phosphors doped with various kinds of activator ions from an aspect of solid-state physics. Mn4+ (3d 3)-activated fluoride phosphor is a good example to understand the fundamentals of such foreign ion-activated phosphors. The luminescence transitions of 2 Eg →4 A 2g in 3d 3-configuration ions are both parity and spin-forbidden transitions and, therefore, one can expect no strong light emission. Herein, Mn4+ luminescence is discussed from an aspect of parity integral. This approach helps better understanding of the peculiar luminescence properties observed in the various 3d 3 ion-activated phosphors. The luminescence properties of the HK3SnF8:Mn4+ and Cs2WO2F4:Mn4+ phosphors are examined in detail as a verification of our proposed model. This model will also be successfully applied to other kinds of activator ions like Cr3+, Mn2+, Eu2+, Eu3+, and Tb3+ in a separate article (II).

A novel red phosphor Cs2NaGaF6:Mn4+ with ultra-strong zero-phonon lines and long wavelength phonon sidebands for high-quality WLEDs

“…However, the splitting energy of the 2 E g level is close to zero and can be neglected, while the splitting energy of the 4 A 2 level is very small, almost close to zero. 29 Nevertheless, we found that the energy between the peak at 15 889 cm −1 and R 1 is 7.9 meV, and the energy between the peak at 15 810 cm −1 and υ 6 (15 710 cm −1 ) is 12.3 meV. Therefore, these two emissions mainly arise from the external lattice vibronic modes (denoted as LM in Fig.…”

“…11,26–28 This is due to the distortion of the local triangular structure of the R 3̄ m space group, which causes the breakdown of the optical selection rules, resulting in a strong ZPL emission intensity. 29…”

“…11,[26][27][28] This is due to the distortion of the local triangular structure of the R3 ˉm space group, which causes the breakdown of the optical selection rules, resulting in a strong ZPL emission intensity. 29 Moreover, the anti-Stokes and Stokes υ 3 , υ 6 consist of two sets of sharp peaks on both sides of the ZPLs. The reason is that the electronic structure and vibrational modes of Mn 4+ ions strongly depend on their local environment.…”

A bright orange-red emitting phosphor Ba9La2W4O24:Eu3+ with double perovskite structure and abnormal thermal quenching behavior

“…Currently, there are two model explanations for the cause of this abnormal thermal quenching behavior, namely the lattice-vibration gaining model 50,51 and electron trap model. In this work, we use an electron trap model based on solid-state physics to illustrate the reasons for this behavior.…”

Luminescence Enhancement of K2LiAlF6:Mn4+ Phosphors by Zn2+-Mediated Charge Compensation for Fast-Response Backlighting Applications

“…However, commonly used K 2 SiF 6 :Mn 4+ (KSF:Mn) phosphors have a long fluorescence decay lifetime of about 7 to 10 ms due to the parity- and spin-forbidden 3d 3 ( 2 E g ) electron transitions in Mn 4+ . So, they cannot achieve the fast response speed required for the application. − Therefore, developing high-efficiency red phosphors with shorter fluorescence lifetimes is essential for improving the performance of Mini-LED-based display terminals. One promising candidate is K 2 LiAlF 6 :Mn 4+ , which has a shorter lifetime (<5 ms) and a similar emission spectrum as KSF:Mn. − …”