Molybdenum substitution simultaneously induced band structure modulation and luminescence enhancement in LiLaMg(W, Mo)O6: Eu3+ red-emitting phosphor for near ultraviolet excited white light diodes

Abstract In this study, LiLaMgW 1-x Mo x O 6 : Eu 3+ phosphors have been synthesized by high-temperature solid-state reaction method. By changing the W O charge transfer (CT) band through Mo 6+ substitution, the excitation band of obtained phosphors had been widened largely and could match well with the InGaN-based LED chips. The crystal structure, diffuse reflection spectra, photoluminescent properties of the LiLaMgW 1-x Mo x O 6 : 0.1Eu 3+ phosphors were investigated as a function of W/Mo ratio. The red shift of charge transfer band (CTB) was observed with the increase of Mo 6+ concentration. Density functional theory (DFT) were performed to calculate the band structure in order to support the excitation band modulation. Moreover, LiLa 1-y MgW 0.7 Mo 0.3 O 6 :yEu 3+ phosphors exhibit strong red emission. The excitation, emission spectra, decay dynamics and thermal stability of the phosphors had been measured and investigated in detail. The quenching concentration of Eu 3+ is up to 20 mol% and the concentration quenching is attributed to the dipole-dipole interaction. Finally, a white-LED device was fabricated by integrating a mixture of optimal red phosphor, commercial green- and blue-emitting phosphors with a near-ultraviolet (UV) InGaN-based LED chip. The results suggest that the Eu 3+ -activated LiLaMgW 0.7 Mo 0.3 O 6 phosphor is a promising red-emitting phosphor for white-LEDs.