The magnetic coupling interaction of Mn2+–Mn2+ in Mn2+-included phosphors could induce a shorter emission decay time, compared with that of isolated Mn2+, which could overcome the photoluminescence (PL) saturation when stimulated by a high photon flux due to the long lifetime of the Mn2+ excited state. However, few studies have directly proved the Mn2+–Mn2+ coupling effect on the PL decay. In this paper, the effect on PL of CsMnCl3 (CMC) and its hydrates is revealed by photomagnetism results, excluding the interference effects of site symmetry and phonon energy. The antiferromagnetic interaction of the CMC is larger when Mn2+ at a photoexcited state than at a dark state, which is contrary to the hydrates with weak Mn2+–Mn2+ interaction. This research not only helps researchers to understand the fundamental optical process but also is instructive for designing high performance Mn2+-doped phosphors in the field of displays and lighting.

Mn2+ emission tends to saturate under irradiation of high flux light, which is first caused by its long decay lifetime ascribing to the spin-forbidden transition of 4T1 → 6A1. Coupling with hetero-transition metal ions to alter the spin state of Mn2+ is a potential way to improve it. In this research, we attempt to provide evidence for the exchange coupling interaction between Mn2+ and Cr3+ in the ZnGa2O4 material and figure out the lifetime variation of Mn2+ emission. A faster decay of Mn2+ emission is achieved when elevating the Cr3+ concentration rather than the Mn2+ concentration, and the dominant cause of energy transfer from Mn2+ to Cr3+ is ruled out. Electron spin resonance results illustrate the stronger spin relaxation of Mn2+ 3d electrons imposed by Cr3+ than that imposed by the other Mn2+ ions. These phenomena suggest the existence of coupling between Mn2+ and the neighboring Cr3+, which is evidenced by the first principles calculation. It is further convinced by the total spin quantum number for the Mn2+, Cr3+ singly doped, and codoped systems, which is close to 3/2, 3/2, and 5/2, respectively, according to the derived magnetic susceptibility data. This research proposes a strategy for anti-saturating the Mn2+ emission in phosphors.

Stability test shows that the luminous efficiency of WLED with CSFM-Y reduces only 4% after duration of 120 h in the testing condition of high humidity (85%) and high temperature (85 °C), while the one with pure CSFM declines 28%.