Enhanced luminescence of a silica‐nitride phosphor; La₃Si₆N₁₁:Ce³⁺by using Cr³⁺‐activated TiO₂ nanoparticles

Abstract

Ce3+‐activated silica nitride phosphors (lanthanum silicate‐nitride [LSN]) are promising thermostable conversion components for white‐light‐emitting diodes, screen technologies, and other optoelectronic applications. Cr3+‐activated TiO2, on the other hand, is a strongly absorbing material depending on its size and optical microenvironment. In this work, we gathered Cr3+‐doped TiO2 and La3Si6N11:Ce3+ in an optically transparent polymethylmethacrylate matrix. Photoluminescence of the binary blends of La3Si6N11:Ce3+/TiO2 and La3Si6N11:Ce3+/TiO2:Cr3+ has been investigated under two different excitation energies by steady‐state and lifetime‐based measurements, respectively. When the microscale La3Si6N11:Ce3+ phosphor and nanoscale TiO2:Cr3+ particles were gathered at a critical concentration, the resulting composite exhibited 3.14‐fold enhancement in the emission signal intensity with respect to the additive‐free phosphor. Upon excitation, the La3Si6N11:Ce3+–TiO2:Cr3+ blend exhibited different excited‐state lifetimes for the nano‐ and microsecond time‐scales compared to the LSN. The microsecond time‐scale measurements performed under 378 nm excitation supported the existence of a potential energy transfer from the TiO2:Cr3+ to the La3Si6N11:Ce3+.