Mechano-Chemical Synthesis and Characterization of Undoped and Mn²⁺ Doped Cspb(Br_1-xCl_x)₃ Halide Perovskite for Light Source Application

All-inorganic halide perovskites (HPs) continue to be of current interest for light source applications (e.g. lasers, LED’s) because of their high emission quantum yields and wide wavelength tunability due to compositional engineering [1]. The development of red and near-IR emitting lead halide perovskites, however, has been hampered by low emission efficiency and instability of iodine based compositions at room temperature. Recent studies employing transition metal or lanthanide doping have demonstrated an alternative approach to achieve red and near-IR emitting HPs structures [2-4]. In this study we report results of the mechano-chemical synthesis of undoped and manganese (Mn) doped CsPb(Br 1-x Cl x ) 3 halide perovskites as emitting materials for light source development. Mechano-chemical synthesis is considered a green chemistry method avoiding the use of complex and time-consuming reactions, energetic-enabled conditions, expensive precursor sources, and hazardous reagents, catalysts, additives, and surfactants. Mechano-chemical synthesis experiments were performed employing a high energy ball-mill and 5N purity lead halide and cesium halide powders. The prepared HPs were evaluated by optical microscopy, SEM, TEM, XRD, and fluorometric measurements. Under UV optical excitation a Mn doped CsPbCl 3 sample exhibited a broad red emission band centers at ~615nm, which was slightly red-shifted compared to the emission from a melt-grown Mn: CsPbCl 3 crystals (see Figure 1). Post synthesis optimization strategies for HPs were also explored including thermal treatment, high-pressure studies, and solvent dependency. Comparative studies of the emission properties of undoped and Mn doped CsPb(Br 1-x Cl x ) 3 prepared by mechano-chemical synthesis, microwave-assisted synthesis, and melt-synthesis will also be presented. Acknowledgment This work was supported by the Army Research Office (grant W911NF1810447) and National Science Foundation (grant NSF-DMR 1827820-PREM). References [1] R. Babu, L. Giribabu, S. P. Singh, "Recent Advances in Halide-Based Perovskite Crystals and Their Optoelectronic Applications", Cryst. Growth Des. 18, 2645 (2018). [2] B. Su, G. Zhou, J. Huang, E. Song, A, Nag, Z. Xia, “Mn 2+ doped metal halide perovskites: structure photoluminescence, and applications”, Laser and Photonics Reviews, 15, 2000334 (2021). [3] U. Hommerich, J. Barnett, A. Kabir, K. Ghebreyessus, K. Hampton, S. Uba, I. Uba, D. Geddis, C. Yang, S.B. Trivedi, S. Fraden, A. Aghvami, "Comparative steady-state and time-resolved emission spectroscopy of Mn doped CsPbCl 3 perovskites nanoparticles and bulk single crystals for photonic applications ", SPIE Proceedings Volume 11682, Optical Components and Materials XVIII, 116821J (2021). [4] U. Hömmerich, D. Hart, A. Kabir, C. Yang, S. B. Trivedi, "Materials development and mid-infrared emission properties of Dy-doped TlPb 2 Br 5 and CsPbCl 3 ," Proc. SPIE 11276, Optical Components and Materials XVII, 112761D (2020). Figure 1