High Performance Perovskite Light-Emitting Diodes with Surface Passivation of CsPbBrxI3-x Nanocrystals via Antisolvent Triggered Ion-exchange.

Inorganic lead halide perovskite nanocrystals (PeNCs) have intensively drawn the attention as efficient light emitting materials for optoelectronic applications due to fine optoelectronic properties with high photoluminescence quantum yield and easily tunable saturated emission color. However, the low stability of the red-emitting PeNCs have become an obstacle because of the uncontrollable iodine substitution from the PeNCs owing weak Pb-I bonding. In this work, we have demonstrated a ligand-mediated post-treatment (LMPT) method using halide ion-pair ligand, tridodecylmethyl ammonium iodide (TrDAI), for the air stable and high-quality red-emitting PeNCs. Through the LMPT method, the optoelectronic properties of red-emitting PeNCs are dramatically improved resulting in the PLQY of 88.7% at 637 ± 2 nm emission with increased carrier lifetime from 20.77 ns to 31.52 ns. We achieve highly efficient red perovskite light-emitting diodes exhibiting a maximum current efficiency of 7.69 cd A-1 and an external quantum efficiency of 6.36% at 637 ± 2 nm electroluminescence emission with a sharp full-width at half maximum of 31 nm.