Lanthanide-doped Mn2+-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 Mn2+-based perovskite-like single crystals using the designed nonstoichiometric precursor ratio. The special crystal structure endows Mn2+ 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 Ln3+ emitters. The incorporations of Yb3+, Er3+, and Ho3+ functionalize the CsMnCl3 single crystals with multiple NIR emissions by virtue of feeding the energy from Mn2+ to Ln3+ 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 Ln3+ 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 Ln3+ ions, and a fundamental understanding of the sensitization-activation mechanisms in Ln3+-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.