A method of improving the luminance of zinc sulfide doped with manganese (ZnS/Mn) thin-film electroluminescent (TFEL) devices is suggested. The addition of small amounts of silver is found to increase the device luminance. It is suggested that silver reduces Mn clustering effects, thereby resulting in fewer nearest neighbor Mn re-absorption interactions and allowing higher Mn doping concentrations. A luminance increase of up to two and a half times from ZnS/Mn,Ag devices compared to ZnS/Mn is observed. The same magnitude of the luminance increase is demonstrated on ZnS/Ho,Ag samples. Silver was found to cause no change in the crystallite size of the phosphor layer and no additional degradation of the device. (C) 2004 Elsevier B.V. All rights reserved.