High-Performance\nPerovskite Light-Emitting Diodes with Surface Passivation of CsPbBr<i>_x</i>I_3–<i>x</i> Nanocrystals\nvia Antisolvent-Triggered Ion-Exchange

Abstract

Inorganic\nlead halide perovskite nanocrystals (PeNCs) have intensively drawn\nattention as efficient light-emitting materials for optoelectronic\napplications due to their fine optoelectronic properties with a high\nphotoluminescence quantum yield and easily tunable saturated emission\ncolor. However, the poor stability of the red-emitting PeNCs has become\nan obstacle because of the uncontrollable iodine substitution from\nthe PeNCs due to weak Pb–I bonding. In this work, we have demonstrated\na ligand-mediated post-treatment (LMPT) method using a halide ion-pair\nligand, tridodecylmethyl ammonium iodide (TrDAI), for the air stable\nand high-quality red-emitting PeNCs. Through the LMPT method, the\noptoelectronic properties of red-emitting PeNCs are dramatically improved\nresulting in a PLQY of 88.7% at 637 ± 2 nm emission with an increased\ncarrier lifetime from 20.77 to 31.52 ns. We achieve highly efficient\nred perovskite light-emitting diodes exhibiting a maximum current\nefficiency of 7.69 cd A^–1 and an external quantum\nefficiency of 6.36% at 637 ± 2 nm electroluminescence emission\nwith a sharp full-width at half maximum of 31 nm.