Oxyfluoride K3MoO2F5·2H2O:Mn4+ red phosphor with enhanced luminescence and moisture resistance for WLED indoor lighting and wide gamut display applications

Abstract

K3MoO2F5·2H2O:Mn4+ (KMOFM) oxyfluoride red phosphor was synthesized by co-precipitation strategy. Due to the non-equivalent doping of Mn4+, the phosphor has a strong ZPL emission peak at 623 nm with high color purity (97%). The crystal field strength and nephelauxetic effect were systematically discussed. By optimizing the synthesis process, the optimal doping concentration of Mn4+ was determined to be 0.02. The surface modification of organic reagents (paraffin wax (PW), oleic acid (OA) and methyl silicone oil (MSO)) can effectively enhance the luminescence intensity and moisture resistance of the phosphors, and the possible surface modification mechanism was also proposed. Meanwhile, the as-synthesized sample exhibits distinguished UV light-induced stability, and the surface modification can also improve the photoinduced stability. Moreover, the luminescence thermal stability and the thermal quenching mechanism were analyzed in detail. Furthermore, the CCT and CRI of the warm WLED devices prepared by the red KMOFM/surface-modified phosphors and yellow Y3Al5O12:Ce3+ phosphor are improved obviously, indicating that the prepared sample is a promising red phosphor applied to WLED lighting field. Noticeably, based on the characteristics of high PLQY (63.09%), high color purity (97%) and short fluorescence lifetime (< 4 ms) of the phosphor, we also fabricated a WLED device with wide color gamut (105.1% NTSC value), indicating that the phosphor can also be well applied to the field of wide color gamut fast response backlight display, which greatly expands the application value of the phosphor.