Learning from a Mineral Structure toward an Ultra‐Narrow‐Band Blue‐Emitting Silicate Phosphor RbNa 3 (Li 3 SiO 4 ) 4 :Eu 2+

Learning from natural mineral structures is an efficient way to develop potential host lattices for applications in phosphor converted (pc)LEDs. A narrow‐band blue‐emitting silicate phosphor, RbNa 3 (Li 3 SiO 4 ) 4 :Eu 2+ (RNLSO:Eu 2+ ), was derived from the UCr 4 C 4 ‐type mineral model. The broad excitation spectrum (320–440 nm) indicates this phosphor can be well matched with the near ultraviolet (n‐UV) LED chip. Owing to the UCr 4 C 4 ‐type highly condensed and rigid framework, RNLSO:Eu 2+ exhibits an extremely small Stokes shift and an unprecedented ultra‐narrow (full‐width at half‐maximum, FWHM=22.4 nm) blue emission band (λ em =471 nm) as well as excellent thermal stability (96 %@150 °C of the initial integrated intensity at 25 °C). The color gamut of the as‐fabricated (pc)LEDs is 75 % NTSC for the application in liquid crystal displays from the prototype design of an n‐UV LED chip and the narrow‐band RNLSO:Eu 2+ (blue), β‐SiAlON:Eu 2+ (green), and K 2 SiF 6 :Mn 4+ (red) components as RGB emitters.