Lead halide perovskite nanocrystals (PNCs) hold promises of developing novel optoelectronics. The quantum confinement effect of these materials provides a convenient strategy to fine-tune their energy and electronic properties. This research identifies a group of heterocyclic bidentate ligands that feature proper affiliation to the surface defect sites of PNCs, which provide effective passivation while grafting functional compounds with their extendable chemical motifs. These heterocyclic ligands combine the X-type and L-type coordination and can stabilize PNCs during the post-synthetic purification. Quantitative NMR study estimates the binding affinity of the novel ligands is 20 to 30 folds greater than the intrinsic ligands. The tightly bound ligands can passivate the surface defect sites and reduces exciton trapping in PNCs. With a close-to-stoichiometric addition of the heterocyclic ligands, the exciton lifetime of the PNC with strong quantum confinement is drastically elongated, resulting in bright blue emission. The binding mode of the heterocyclic ligands was characterized with NMR and vibrational spectroscopy and interpreted with quantum chemical simulation. The strong surface affiliation and the extendable conjugated structures of the novel ligands make them suitable anchors to graft functional organic molecules on the PNC surface. Organic/inorganic heterojunctions with different band alignments are fabricated through grafting molecules that can serve as charge carrier donors and acceptors to PNCs. Photophysical mechanisms of charge carrier migration within these hybrid heterojunctions are investigated with optical spectroscopy.

Searching proper surface interactions to mediate exciton kinetics in colloidal perovskite nanocrystals with strong quantum-confinement

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.