Mn2+-Based narrow-band green-emitting Cs3MnBr5 phosphor and the performance optimization by Zn2+ alloying

To discover new narrow-band green-emitting phosphors is a challenge for backlighting light-emitting diodes (LEDs) used in liquid crystal displays (LCDs). The synthesis and optical properties of Cs₃MnBr₅ are demonstrated herein. The intrinsic Mn²⁺ luminescence without concentration quenching leads to intense green emission at 520 nm with narrow full width at half maximum of 42 nm and high photoluminescence quantum yield (PLQY) of 49% under the excitation at 460 nm. When a small amount of Zn²⁺ is introduced into Cs₃MnBr₅, the luminescence intensity decreases slightly. However, the thermal stability of Cs₃MnBr₅ is improved from 82% to 87% with the intensity values at 423 K compared to that at 298 K. The white LED device fabricated using Cs₃Mn_0.96Zn_0.04Br₅ (green) and K₂SiF₆:Mn⁴⁺ (red) phosphors with a blue LED chip exhibit a high luminous efficiency (107.76 lm W⁻¹) and wide color gamut (101% National Television System Committee standard (NTSC) in Commission Internationale de L’Eclairage (CIE) 1931 color space), demonstrating its potential application in wide color gamut LCD backlights.