Broadband near-ultraviolet excited La2Mo2O9:Eu3+ red-emitting phosphors with high color purity for solid-state lighting

Abstract

A series of different Eu3+ ions incorporated La2Mo2O9 phosphors exhibiting photoluminescence (PL) peaks in the red region (613 nm; 5D0→7F2) were successfully synthesized by a citrate sol-gel method. Under the 351 nm excitation, the optimal doping concentration of Eu3+ ions was identified to be 25 mol% with higher PL emission intensity and further the concentration quenching mechanism was governed by electric diploe-diploe interaction. More importantly, the optimized phosphor was demonstrated high color purity while the Commission Internationale de I'Eclairage chromaticity coordinates were (0.661, 0.339). The intrinsic radiative transition lifetime for the optimized red phosphor was calculated to be 530.7 μs and the local structure environment of Eu3+ ions in the La2Mo2O9 host matrix was also analyzed by the Judd-Ofelt theory. Moreover, a red-emitting light-emitting diode (LED) device was fabricated by combing a near-ultraviolet LED chip with the optimized red phosphor, which exhibits a dazzling red light. Based on the obtained results, the Eu3+ ions activated La2Mo2O9 phosphors are expected to be as a promising red-emitting phosphor for solid-state lighting.