Moisture-Insensitive, Phase-Stable Indium-Based Metal Halides and Their Light-Emitting Applications

Ternary indium (In)-based metal halides are gaining increased attention as promising lead (Pb)-free alternatives for light-emitting diodes (LEDs) owing to their broadband emission and high photoluminescence quantum yields (PLQYs). However, most of the pure In-based compositions suffer from instability against moisture and thermal stress, leading to a rapid degradation of material and hence their optical properties. Herein, a new kind of organic-inorganic hybrid In-based metal halide BA6InCl9 (BA+ = C4H11N+) is presented, which exhibits stable crystal structure and material composition at both ambient (over 5 months) and heating conditions (up to 200 degrees C). Besides, the Huang-Rhys factor of approximate to 4.94 determined for BA6InCl9 is considerably smaller than most Pb-free perovskites, which suggests a relatively weak exciton-phonon coupling in these crystals. By trace amounts of antimony (III) (Sb3+) doping, the PLQY of the BA6InCl9 single crystals can be markedly improved from approximate to 25% to 95%, and the ensuing down-conversion LEDs exhibit bright orange-red emission with an external quantum efficiency of 0.12%, which retains approximate to 50% of the initial luminance after 380 min of continuous operation in ambient air. It is forseen that the study will prompt future research on In-based metal halides and their use in stable light-emitting applications. A new kind of coordinating water-free, ternary indium (In)-based metal halide BA6InCl9 (BA+ = C4H11N+) is developed, which exhibits high resistance to thermal stress up to 200 degrees C and maintains stable crystal structure under ambient atmosphere (Relative Humidity approximate to 40%) for over 5 months, paving the way for the fabrication of high-efficiency light-emitting devices.image