Enhanced luminescence of Tb3+ by efficient energy transfer from Ce3+ in Sr2B5O9Cl host

Abstract

Ce3+ and Tb3+ co-doped Sr2B5O9Cl phosphors with intense green emission were prepared by the conventional high-temperature solid-state reaction technique. A broad band centered at about 315 nm was found in phosphor Sr2B5O9Cl: Ce3+, Tb3+ excitation spectrum, which was attributed to the 4f-5d transition of Ce3+. The typical sharp line emissions ranging from 450 to 650 nm were originated from the 5D4 → 7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions. The photoluminescence (PL) intensity of green emission from Tb3+ was enhanced remarkably by co-doping Ce3+ in the Tb3+ solely doped Sr2B5O9Cl phosphor because of the dipole–dipole mechanism resonant energy transfer from Ce3+ to Tb3+ ions. The energy transfer process was investigated in detail. In light of the energy transfer principles, the optimal composition of phosphor with the maximum green light output was established to be Sr1.64Ce0.08Tb0.1Li0.18B5O9Cl by the appropriate adjustment of dopant concentrations. The PL intensity of Tb3+ in the phosphor was enhanced about 40 times than that of the Tb3+ single doped phosphor under the excitation of their optimal excitation wavelengths.