The novel red persistent phosphor CaS:Yb2+, Cl− potentially applicable in AC LED

Abstract

In this work, a novel CaS:Yb2+, Cl− Long Persistent Luminescence (LPL) phosphor was prepared by a solid-state reaction method in carbon reduction atmosphere. The Cl− ion was introduced to sensitize the luminescence of Yb2+ ion. The crystal structure was characterized by X-ray diffraction (XRD). The Photoluminescence (PL) and Photo-Stimulated Luminescence (PSL) properties of the as-prepared phosphors under the mercury lamp were systematically investigated. The bright red long afterglow in the range of 580–750 nm with a maximum at 650 nm has the high color purity and can last 5 min. It is worth mentioned that, in this phosphor, the attenuation of the afterglow luminescence is little in the first second. The CaS:Yb2+, Cl− with a luminescent center at 650 nm can be used to increase the color saturation of white alternating current (AC) LEDs by coating phosphor on a blue AC LED chip.