Highly Luminescent Earth‐Benign Organometallic Manganese Halide Crystals with Ultrahigh Thermal Stability of Emission from 4 to 623 K

Abstract The phosphor‐converted light‐emitting diode (PC‐LED) has become an indispensable solid‐state lighting and display technologies in the modern society. Nevertheless, the use of scarce rare‐earth elements and the thermal quenching (TQ) behavior are still two most crucial issues yet to be solved. Here, this work successfully demonstrates a highly efficient and thermally stable green emissive MnI₂(XanPO) crystals showing a notable photoluminescence quantum yield (PLQY) of 94% and a super TQ resistance from 4 to 623 K. This unprecedented superior thermal stability is attributed to the low electron–phonon coupling and the unique rigid crystal structure of MnI₂(XanPO) over the whole temperature range based on the temperature‐dependent photoluminescence (PL) and single crystal X‐ray diffraction (SCXRD) analyses. Considering these appealing properties, green PC‐LEDs with a power efficacy of 102.5 lm W⁻¹, an external quantum efficiency (EQE) of 22.7% and a peak luminance up to 7750 000 cd m⁻²are fabricated by integrating MnI₂(XanPO) with commercial blue LEDs. Moreover, the applicability of MnI₂(XanPO) in both micro‐LEDs and organic light‐emitting diodes (OLEDs) is also demonstrated. In a nutshell, this study uncovers a candidate of highly luminescent and TQ resistant manganese halide suitable for a variety of emission applications.