Synergistic effect of multidentate ligands on CsPbI3 perovskite nanocrystals surface for high efficiency deep red light-emitting diode

Abstract

In order to improve all-inorganic perovskite nanocrystals (NCs) optical properties and stability, multidentate chelating ligands of Ethylenediaminetetraacetic Acid (EDTA) and Glutathione (GSH) were introduced into CsPbI3 NCs system. After ligand-exchange, a great improvement in both photoluminescence (PL) and electroluminescence (EL) performance around 682 nm was observed, which shows the trap state density dramatically decline due to the synergistic effect of both EDTA and GSH on NCs surface. Furthermore, the photoluminescence quantum yield (PLQY) improved from 72.9% to 94.3% and their PL stability was prolonged. Meanwhile, E + G treated CsPbI3 NCs could maintain their optical performance in the polar environment without dissociation, retaining strong fluorescence in ethanol beyond one month. A deep red light-emitting device based on the E + G treated CsPbI3 NCs as the emission layer was fabricated. High electroluminescence of 584 cd m−2 and external quantum efficiency (EQE) of 8.15% were obtained by E + G treated NCs, which indicated the synergistic effect of EDTA and GSH was feasible and effective in CsPbI3 NCs surface passivation. This work provided a new thought to combine different ligand-exchange strategies with their virtues for perovskite nanocrystals with more comprehensive performance.