Ultrahighly Efficient Narrowband Red Luminescence of Uniquely Distorted Mn4+ Octahedron in the Feldspar‐Type LED Phosphor

Abstract

AbstractThe mineral structure‐inspired discovery of red phosphors has become a research hotspot that can help compensate for the missing red components in cold white light‐emitting diodes (WLEDs). Herein, first the feldspar‐type structure is utilized to develop narrowband red‐emitting CaAl2Si2O8:Mn4+/Mn4+, Mg2+ phosphors. Rietveld refinement results confirm the Mn4+ occupation of the distorted [Ca1O6] octahedron, resulting in a strong nephelauxetic effect, and thus exhibits bright red luminescence with a narrow full width at half maximum (43 nm). Compared with CaAl2Si2O8:Mn4+, the fluorescence intensity of CaAl2Si2O8:Mn4+, Mg2+ is further enhanced by up to 210% owing to the decreasing nonradiative decay rate from 2Eg excited state, which weakens the concentration quenching effect resulting from energy migration along the adjacently aggregated Mn4+. CaAl2Si2O8:Mn4+, Mg2+ shows preferable thermal stability with an ultrahigh quantum efficiency (90.3%), surpassing other current Mn4+‐doped oxide phosphors and UCr4C4‐type nitride phosphors. A fabricated prototype WLED obtains ideal warm white light with a low correlated color temperature (3081 K) and a wide color gamut covering 112% of the National Television System Committee standard. Guided by natural mineral‐type structural prototypes, this study demonstrates the possibility of designing a uniquely distorted local structure to achieve a superior luminescence performance of Mn4+ for warm WLEDs.