Stapled ligand for synthesis of highly emissive and stable CsPbBr3 perovskite nanocrystals in polar organic solvent

Colloidal cesium lead halide perovskite nanocrystals (CsPbX3 PNCs) are prone to instability due to low lattice energy and dynamic ionic bonding between the PNC core and the inorganic-organic interface. To address this issue, we propose a stapled ligand, perfluoroglutaric acid (PFGA), that can effectively passivate the surface of CsPbBr3 PNCs through atomic-scale double chelating coordination with Pb2+ between neighboring [PbBr6](4)(-) unit cells. Theoretical calculations show that this precise double chelating on the surface of CsPbBr3 PNCs can achieve a much stronger bonding energy (-5.19 eV) compared to single-chelated perfluoroadipic acid (-1.42 eV) or other similar ligands with trivial changes in chain length. The PFGA enables CsPbBr3 PNCs to achieve a high photoluminescence quantum yield of over 85% with a single acid as a capping agent, as well as outstanding dispersion in a variety of polar solvents. Furthermore, the PFGA-capped CsPbBr3 PNCs exhibit excellent purification stability after five rounds of vigorous washing and long-term stability after more than six months of storage within ethanol, which has been successfully applied for chloride sensing in different circumstances. Our findings provide insight into the design of surface engineering strategies to produce highly emissive and stable PNCs and broaden the sensing field of PNCs in polar media.