Multidentate Ligand-Passivated CsPbI₃ Perovskite Nanocrystals for Stable and Efficient Red-Light-Emitting Diodes

Abstract

CsPbI3 nanocrystals (NCs) have become a research hot spot in the field of light-emitting diodes (LEDs). Whereas, the long chain ligands with weak affinity to CsPbI3 NCs have prevented their further development and commercialization. Herein, a novel multidentate short ligand tetramethylthiuram disulfide (TMTD) was employed via a ligand exchange process to enhance hole mobility and decrease trap density of the CsPbI3 NCs film. Therefore, TMTD passivated CsPbI3 NCs LED exhibited 20.65% maximum external quantum efficiency and 3861 cd/m2 maximum luminance. Furthermore, TMTD passivated CsPbI3 NCs LED exhibited good operational stability with a 128 min half-lifetime. This strategy using multidentate short ligand passivation provides an effective way to promote perovskite LED development and commercialization.

Influence of Binary Ligands in Designing Cesium Lead Halide (CsPbX3, X = Cl, Br, I) Perovskite Nanocrystals-Oleic Acid and Oleylamine

“…Also, growing CsPbBr 3 NCs in the micelles of a polymeric multidentate ligand, polystryrene-block-poly-2vinyl pyridine (PS-b-P2VP), was found to be useful in reducing the polar solvent diffusion into the Cs LHP NCs [160]. Multidentate ligands such as ethylenediamine tetraacetic acid (EDTA) [161,162], trithiocarbonate terminated polymeric ligand [163], poly-ethylene glycol (PEG)-based polymeric molecule [151,164], polyethyleneimine [165], quaternary ammoniumor imidazolium-based polysalt ligand [166,167], picolinate [168], sulphur-tributylphosphine (S-TBP) bidentate ligand [169], tetramethylthiuram disulfide (TMTD) [170], etc., have proven their strong binding ability with the surface of Cs LHP NCs. Zeng et al used bis(2,4,4-trimethylpentyl) phosphonic acid to protonate a multidentate amine ligand, N -(2-aminoethyl)-N -hexadecylethane-1,2-diamine (AHDA) [171].…”

“…This shows that novel ligands with a higher binding energy value could be resistant to traditional washing solvents of Cs LHP NCs and retain long-term optical properties. From the application point of view, the surface-modified Cs LHP NCs using zwitterionic and multidentate ligands are beneficial for photocatalysis applications, as evidenced by their high stereoselectivity in C-C oxidative coupling reactions [152,172] and also in the fabrication of light-emitting diodes (LEDs) [146,165,170]. Similar to zwitterionic ligands, multidentate ligands are also helpful in stabilizing Cs LHP NCs with improved robustness.…”