A novel bifunctional short-chain fluoroammonium ligand boosts conductivity, luminescence and stability of CsPbX3 quantum dots

Cesium lead halide perovskite quantum dots (CsPbX 3 QDs) exhibit outstanding optoelectronic properties but suffer from structural instability and luminescence degeneration. The long-chain ligands widely adopted to stabilize CsPbX 3 QDs exhibit poor charge transport due to their weak binding and insulating nature, which is unfavorable for optoelectronic applications. To address this, we developed a novel short-chain fluoroammonium ligand, octylammonium fluoride (OTAmF), for the post-treatment of CsPbX 3 QDs. The fluoride ions (F − ) in OTAmF effectively passivate bromine vacancies, whereas the short-chain ammonium cations enhance surface passivation and carrier transport. This strategy significantly improved the photoluminescence quantum yield (PLQY) of green-emitting CsPbBr 3 QDs from 56.8 % to 96.4 %, doubled their thin-film conductivity, and dramatically enhanced their photostability, thermal stability, and long-term storage stability. The approach was successfully extended to blue- (CsPbBr 1.8 Cl 1.2 ) and red-emitting (CsPbBr 0.8 I 2.2 ) QDs, universally increasing their PLQY and stability. Density functional theory (DFT) calculations revealed that, compared with OA (0.73 eV) and OAm (0.27 eV), OTAmF has a superior binding energy (1.74 eV) and enhanced charge transfer and defect passivation capabilities. This OTAmF post-treatment strategy provides a promising pathway for developing high-performance optoelectronic devices based on perovskite QDs.