Structural design of new Ce3+/Eu2+-doped or co-doped phosphors with excellent thermal stabilities for WLEDs

Abstract

In widely used phosphor-converted white-light-emitting diodes, thermal stability is one of the key indexes for phosphors. It not only implies that the emission intensity should remain unchanged, but also requires a steady peak pattern and position when the phosphors work at varying temperatures. For realizing excellent thermal stability, the thermal behaviors of various phosphors have been discussed and clearly explained in this review article, which focuses on single-doped Ce³⁺ or Eu²⁺ or co-doped oxides, oxynitrides, and nitride-based phosphors. These results indicate that the luminescence properties of different phosphors would show abundant changes under varying temperatures, which mainly relies on the crystal structure of the host. By analyzing the relationship between the thermal behavior and host lattice of the phosphors in different matrixes, it has been concluded that a rigid crystal structure combined with a symmetric site is the precondition for phosphors to realize excellent thermal stability; therefore, this work summaries various types of systems with a rigid framework and several ways to prevent phosphors from undergoing thermal disturbances. This provides a research direction toward exploring new and stable phosphors and ways to improve the thermal stability of existing phosphors.