Simultaneously enhanced luminescence efficiency and moisture stability of submicron Cs2MnF6:Si4+ phosphors via surface passivation

Mini/Micro-LED backlight systems require color conversion layers that combine submicron size with high absorption efficiency. However, commercial phosphors are difficult to meet this demand due to their relatively large particle size. The Cs 2 MnF 6 system demonstrates a unique advantage due to its intrinsic high absorption efficiency. In this study, submicron-sized Cs 2 MnF 6 was successfully prepared via anti-solvent synthesis method. Furthermore, a Si 4+ reverse doping strategy was employed (Cs 2 MnF 6 :Si 4+ ) to effectively suppress concentration quenching. At the optimal doping concentration, the emission intensity reaches 3523 times that of the undoped Cs 2 MnF 6 host. Subsequently, surface passivation treatment was applied with a Mn 4+ -free Cs 2 SiF 6 coating. This treatment not only suppressed surface quenching, further increasing the luminescence intensity, but also significantly improved the material's moisture resistance. The finally obtained Cs 2 MnF 6 :Si 4+ @Cs 2 SiF 6 phosphor has an average particle size of approximately 800-900 nm and a high absorption efficiency of 48.4%. Its luminescence intensity is 4.25 times that of the un-passivated sample. And this material retained 75% of its initial luminescence intensity after 240 minutes of immersion in deionized water. In contrast, the untreated sample remained only 16.4%. These advancements highlight the significant potential of this material in mini/micro-LED backlight systems, offering new possibilities for the development of next-generation display technologies.