Realizing red/orange emission of Eu2+/Ce3+ in La26−xSrxSi41Ox+1N80−x (x = 12.72–12.90) phosphors for high color rendition white LEDs

Abstract

Rare-earth-activated phosphors play key roles in controlling the optical quality of phosphor-converted white light-emitting diodes (pc-wLEDs), but it is still a challenge to discover new phosphors with interesting properties or structures. In this work, we applied the single-particle-diagnosis approach to screen and find phosphors in a multi-nary system La–Sr–Si–O–N, and discovered broadband red- or orange-emitting La_26−xSr_xSi₄₁O_x+1N_80−x:Eu²⁺/Ce³⁺ (x = 12.72–12.90) phosphors. The single-crystal structure refinement results show that La_13.1Sr_12.9Si₄₁O_13.9N_67.1 (x = 12.9) crystallizes in the hexagonal system (space group P, No. 174, Z = 3) with a = b = 17.3506 (5) Å, c = 22.4052 (6) Å. The crystal structure of La_26−xSr_xSi₄₁O_x+1N_80−x consists of three-dimensional frameworks formed by edge-, corner- and face-sharing Si(O,N)₄ tetrahedra, where 23 independent and disordered La/Sr atoms are embedded in one unit cell. Under 450 nm excitation, the Eu²⁺-doped sample shows broad band red emission (λ_em = 643 nm, full-width at half maximum (FWHM) = 3477 cm⁻¹ (142 nm)), and the Ce³⁺-doped one gives an orange emission (λ_em = 568 nm, FWHM = 4700 cm⁻¹ (155 nm)). This makes La_26−xSr_xSi₄₁O_x+1N_80−x:Eu²⁺/Ce³⁺ an interesting phosphor for high color rendering pc-wLEDs, and an additional example for exploring the structure–property relations.