Thermal quenching at the microscopic level in multi-phase thiosilicate phosphors

Abstract Europium (Eu 2+ ) doped calcium thiosilicate (Ca 2 SiS 4 ) is interesting as conversion phosphor for light-emitting diodes (LEDs), because of its yellow-to-red emission, depending on the europium concentration. However, for elevated europium concentrations two phases appear which is reflected in the temperature dependency of the emission spectrum. In this work we study the emission spectrum and thermal quenching behaviour at the microscopic level, by performing temperature dependent cathodoluminescence spectroscopy in a scanning electron microscope. A clear relation between the local europium concentration and the thermal quenching is obtained. This proves useful to explain the luminescence properties of the bulk phosphor.