Luminescence properties of Mn2+-doped Li2ZnGeO4 as an efficient green phosphor for field-emission displays with high color purity

Abstract

Green emitting Li₂ZnGeO₄:Mn²⁺ phosphors were synthesized through a high temperature solid-state reaction process. X-Ray diffraction, field emission scanning electron microscopy, photoluminescence (PL) and cathodoluminescence (CL) spectra were utilized to characterize the synthesized samples. Under UV and electron-beam excitation, the pure Li₂ZnGeO₄ sample shows a blue emission due to defects, while the Li₂ZnGeO₄:Mn²⁺ sample exhibits a green emission corresponding to the characteristic transition of Mn²⁺ (⁴T₁ → ⁶A₁). In particular, the CL intensity (brightness) of Li₂ZnGeO₄:Mn²⁺ is higher than that of commercial green phosphor ZnO:Zn. In addition, the CL properties of Li₂ZnGeO₄:Mn²⁺ phosphor, the dependence of CL intensity on accelerating voltage and filament current, the decay behavior of CL intensity under electron bombardment, and the stability of CIE chromaticity coordinates, have been investigated in detail. The results indicate that the as-prepared Li₂ZnGeO₄:Mn²⁺ phosphor has a good CL intensity and CIE coordinate stability with green emission under low-voltage electron beam excitation. Therefore, Li₂ZnGeO₄:Mn²⁺ is a promising green phosphor for application in full-color field-emission displays.