Enhanced, shortened and tunable emission in Eu3+ doped borosilicate glasses by Cu+ co-doping

Abstract

A series of Cu+/Eu3+ co-doped borosilicate glasses have been successfully prepared by melt-quenching method. As proved by transmission spectra, the copper ions are univalent in the investigated borosilicate glasses. Under ultraviolet (UV) excitation at 325 nm, the emission intensity of Eu3+ increased by nearly double due to a large overlapping between the Cu+ and Eu3+ emission peaks. The decreased excitation intensity in UV region and shortened emission lifetime of Cu+ in association with presence of Eu3+ ions consistently suggest an energy transfer process from Cu+ to Eu3+ ions. On the other hand, the partially allowed transition of Cu+ makes contribution to the red emission of Eu3+ at 611 nm in Cu+/Eu3+ co-doped samples, thus shortening the lifetime from the conventional millisecond (∼1.86 ms) to the microsecond (up to around 37 μs) regime. Besides, tunable light is realized by combining the blue-green emission from Cu+ ions with the orange-red one from Eu3+ ions. The light can be continuously tuned by changing the Cu+/Eu3+ concentration ratio, indicating that the present novel Cu+/Eu3+ co-doped borosilicate glasses are potential as fast response and tunable photoluminescence materials.