The success of colloidal semiconductor nanocrystals (NCs) in science and optoelectronics is inseparable from their surfaces. Unlike the well-established covalent ligand capping of traditional semiconductor NCs, the functionalization of lead halide perovskite (LHP) NCs poses great challenges due to their structural instability.
Maksym V. Kovalenko, ETH Zurich, et al. , believe that extensive and facile molecular engineering of phospholipids as zwitterionic surfactants could provide highly tailored surface chemistry for metal halide NCs. Molecular dynamics simulations inferred that the ligand-NC surface affinity is mainly affected by the structure of the zwitterionic headgroup, especially the geometric adaptation of the anionic and cationic moieties in the surface lattice sites, which was confirmed by NMR and FTIR data.
Lattice-matched primary ammonium phospholipids enhance the structural and colloidal integrity of organic-inorganic hybrid LHPs (FAPbBr3 and MAPbBr3) and lead-free metal halide NCs. The molecular structure of the organic ligand tail determines the long-term stability of the colloid and its compatibility with solvents of different polarities, from hydrocarbons to acetone and alcohols. These NCs exhibit photoluminescence quantum yields (PL QY) above 96% in solution and solids with minimal PL intermittency at the single particle level, average ON fractions up to 94%, and are bright and highly pure (approximately 95%) ) single photon emission.
Morad, V., Stelmakh, A., Svyrydenko, M. et al. Designer Phospholipid Capping Ligands for Soft Metal Halide Nanocrystals. Nature (2023).