LAUSR

Abstract Mn4+-doped fluoride phosphors are attractive for application in white solid-state lighting devices because their distinct red emission can improve the color rendering index, while the earth-abundance of Mn4+ ions can reduce the production cost. However, highly hazardous HF is used as the fluoride source in the synthesis processes, which requires extreme caution. In this review, we introduce various methods for synthesizing Mn4+-doped fluoride phosphors, categorized according to the presence or absence of HF in the synthesis. The underlying optical properties of the phosphors fabricated using the various methods are discussed. In addition, in the discussion of each method, we emphasize on the key factors and strategies for developing phosphors. Finally, this review highlights perspectives on and future directions for the safe synthesis of Mn4+-doped fluoride phosphors to achieve solid-state lighting devices with superior optical properties.