Lanthanide-doped Mn-based perovskite-like single crystals: Switching on highly thermal-stable near-infrared emission and LED device.

Metal halide perovskites (MHPs) have sparked ongoing research interest due to their high-performance optoelectronic properties. However, blue-light excitable near-infrared (NIR) emitting MHPs is still inaccessible and the achievement of robust thermal-quenching resistance so far remains a huge challenge. In this work, we report on the synthesis of lead-free all-inorganic Mn-based perovskite-like single crystals using the designed nonstoichiometric precursor ratio. The special crystal structure endows Mn with efficient blue light excitation and red emission, which enables the capabilities of a good matching with commercial blue LED chips and an efficient sensitization for Ln emitters. The incorporations of Yb, Er, and Ho functionalize the CsMnCl single crystals with multiple NIR emissions by virtue of feeding the energy from Mn to Ln via multi-channels. Most remarkable is the achievement of the robust thermal-quenching resistance, exhibiting (near-) zero-thermal-quenching and even anti-thermal quenching, of the Ln NIR emissions above room temperature. Finally, as a proof-of-concept study, a prototype of an NIR-LED device was fabricated. This work not only provides a general strategy to unlock the blue-light excitable NIR emission from f-f transitions of Ln ions, and a fundamental understanding of the sensitization-activation mechanisms in Ln-functionalized manganese (Ⅱ)-based perovskite-like phosphor, but also endows the MHPs with optical functionalities for the future high-potential applications, such as NIR phosphor-converted LEDs, and optical telecommunication.