High‐Energy Ball Milling Synthesize All‐Inorganic Lead‐Free Green Emitting Cs3MnBr5 Crystals

Abstract Light Emitting Diodes (LEDs) are the key to new generation displays. New semiconductor electron–hole recombination layer is the key to high‐performance LEDs. Although all‐inorganic quantum dot (QD) materials have the advantages of wide color gamut and narrow emission peaks, they face issues of toxicity of heavy metal ions and stability of QDs, the synthesis method is highly polluting and difficult to achieve industrial production. Thereby, lead‐free all‐inorganic phosphor with narrow FWHM needs to be explored. A new synthesis method is required to be investigated. All‐inorganic Mn 2+ bromide (Cs 3 MnBr 5 ) is easy to synthesize and has low toxicity and superior luminescent properties. However, most synthesis methods rely on liquid‐phase reaction systems and cannot achieve highly efficient synthesis. High‐energy ball milling is an efficient method and has enormous potential for industrial production. In this paper, this method is used to synthesize Cs 3 MnBr 5 , and then Cs/Mn ratio, ball milling time, and ligand usage are studied. Furthermore, a new phase transformation of all‐inorganic Mn 2+ bromide is discovered, and the mechanism of high‐energy ball milling is interpreted combining with phase transformation process. This article brings a new method to synthesis of all‐inorganic Mn 2+ bromide, explains the mechanism of ball milling, and expands the phase transformation of all‐inorganic Mn 2+ bromide.