Photoluminescence of Mechanochemically Manufactured Rare‐Earth Doped CsPbCl₃ Microcrystals

Lanthanide‐activated CsPbX 3 perovskites (Ln 3+ :CsPbCl 3 ) hold immense promise for the development of next‐generation solid‐state lasers. Realizing their full potential hinges on achieving controlled lanthanide concentrations with homogenous distribution throughout the perovskite host—a considerable material processing challenge that hinders widespread application. This work introduces a robust, scalable mechanochemical synthesis for producing both singly doped Ln 3+ :CsPbCl 3 (Ln 3+ = Pr 3+ , Nd 3+ , Ho 3+ , Er 3+ , Yb 3+ ) as well as co‐doped Ln 3+(I) /Ln 3+(II) :CsPbCl 3 (Ln 3+(I) /Ln 3+(II) = Nd 3+ /Yb 3+ , Ho 3+ /Pr 3+ , Er 3+ /Pr 3+ ) microcrystalline powders. Complementary structural characterization techniques (e.g., X‐ray diffraction, X‐ray photoelectron spectroscopy, energy‐dispersive X‐ray spectroscopy, and X‐ray fluorescence) directly quantify doping concentration and confirm homogeneous Ln 3+ distribution throughout the powders. Detailed photoluminescence (PL), PL excitation, and PL lifetime measurements reveal distinct emissive and absorptive states in the visible to short‐wave infrared (IR) stemming from the dopants. Melt‐grown crystals, derived from mechanochemically prepared powders, exhibit enhanced PL lifetimes compared to their source powders and are transparent at IR emission wavelengths. Overall, this mechanochemical approach allows for considerable control over dopant incorporation, yielding powders that are well‐suited for the melt‐growth of rare‐earth‐doped single crystals and the future development of halide perovskite‐based solid‐state lasers.