Identifying the Emission Centers and Probing the Mechanism for Highly Efficient and Thermally Stable Luminescence in the La3Si6N11:Ce3+ Phosphor

Nitride La3Si6N11:Ce3+ is an important commercial phosphor for high-power white light-emitting diodes due to its strong resistance toward thermal quenching and sufficient emission efficiency. However, the underlying mechanisms of this high performance is still a mystery. Also, the emission properties of Ce3+ in two kinds of crystallographic sites are currently in dispute. Here, we confirmed the yellow emission ascribed to CeLa(2) luminescence center and proposed a blue emission owning to CeLa(1) luminescence center through both theoretical and experimental methods. Particularly, we find an unusual efficient and fast energy transfer from CeLa(1) to CeLa(2) due to a large spectral overlap between the emission of CeLa(1) and the absorption of CeLa(2), and efficient electron transfer from defects to 5d orbital at high temperature, which shows high relevance to the highly efficient yellow emission and thermal stability of this material. This study presents a full and new understanding toward this special phosphor and provides useful insights into designing highly efficient and thermally stable luminescent materials for future lighting.