High-conformational-entropy tail zwitterionic ligand enables colloidally stable CsPbBr3 perovskite nanocrystals

Modulating the dynamic surface of colloidal perovskite nanocrystals (PNCs), which is the dominant factor governing their stability, has been recognized as a promising strategy to improve their luminescence performance and stability. However, most current ligand design principles focus on strongly binding head groups while overlooking the important influence of molecular tail structures on the luminescence and colloidal dispersibility of the nanocrystals. To address this, a high-conformational-entropy tail zwitterionic ligand, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) with branched and unsaturated tails was employed for the post-synthetic treatment of CsPbBr 3 NCs. The zwitterionic head groups (–PO 4 - /–NH 3 + ) firmly bind to the nanocrystal surface through multi-site synergistic interactions, securing effective surface passivation. More importantly, the branched alkyl tails of DOPE possess high configurational entropy, which significantly enhances the spatial rotational freedom of the ligand tails in solution and improves their interaction with the solvent, thereby substantially increasing the colloidal dispersibility. Benefiting from this high-conformational-entropy tail design, the photoluminescence quantum yield (PLQY) of CsPbBr 3 NCs increases to 93.4%, the uniformity of the solid film is improved, and excellent colloidal stability is achieved under long-term storage, polar solvents, high-temperature, and UV light conditions. This work demonstrates the value of molecular tail structure design in tuning the stability of colloidally dispersed perovskite nanocrystals.