Long Wavelength Extension of the Excitation Band of LiEuMo[sub 2]O[sub 8] Phosphor with Bi[sup 3+] Doping

Abstract

Bi-doped red phosphor series LiEu1−xMo2O8:xBiLiEu1−xMo2O8:xBi were prepared by solid-state reactions which present bright red luminescence (615nm)(615nm) dominated by a D05→F27D05→F27 transition of Eu3+Eu3+ . With Bi3+Bi3+ doping, the excitation bands of the phosphors extend to longer wavelength (from 350to380nm350to380nm ), and the excitation efficiency for optimized Bi3+Bi3+ content is dramatically increased, which favors the phosphors for the white-light ultraviolet light emitting diode applications. The luminescent model for the phosphors studied in this work is proposed. Because the 6p level of Bi3+Bi3+ is immerged in the conduction band (CB), the excitation 6s→6p6s→6p of Bi3+Bi3+ is overlapped by the excitation 6s→CB6s→CB , which results in extension of the excitation band. The absorbed energy by the excitation 6s→CB6s→CB can be effectively transferred to Eu3+Eu3+ , but the 6p→6s6p→6s emission of Bi3+Bi3+ disappears.