Translucent red-emitting AlN: Mn phosphor ceramics with high luminescence thermal stability

Abstract

Developing new phosphor ceramics with higher thermal conductivity is a matter of priority for high power solid-state lighting. Herein, translucent red-emitting AlN: Mn phosphor ceramic with high thermal conductivity (72.37 W m−1 K−1 at 25 °C) and high luminescence thermal stability are successfully fabricated by pressureless sintering at 1800 °C for 3 h. Preparation process, photoluminescence, afterglow and electronic compensation mechanisms were discussed in detail. TEM analysis showed that the tiny grain boundaries are composed of disordered Al2O3 phases. The EPR and TL spectra were used to reveal the O-related trap distribution. The AlN: Mn phosphor ceramics have brightly red afterglow with the longest afterglow time of 88 s and possess high luminescence thermal stability, that is to say, the luminescence intensity at 250 °C preserves 93.7% of that at room temperature. The encapsulated AlN: Mn LED device has a very bright red emission peak at 598 nm with a color purity of about 99%, indicating great application potential in solid-state lighting.