Mn²⁺‐Based Luminescent Metal Halides: Syntheses, Properties, and Applications

Abstract Lead‐free metal halides are considered a new generation of optoelectronic materials due to their low toxicity, superior optoelectronic properties, ease of synthesis, structural diversity, and low cost. In particular, Mn 2+ ‐based metal halides have earned intensive attention owing to their high emission quantum efficiency, rich physical properties (e.g., triboluminescence and stimuli‐responsivity), low cost, and toxicity. Due to the different coordination environments of Mn ions, Mn 2+ ‐based metal halides can exhibit green, red, and near‐infrared emissions. This review summarizes the recent progress of Mn 2+ ‐based metal halides in synthesis methods, emission mechanisms, photophysical properties, and representative applications in X‐ray scintillations, white light‐emitting diodes, optical anti‐counterfeiting technologies, and fluorescent sensors. Finally, the challenges and potential research directions toward developing Mn 2+ ‐based metal halides are also predicted.