Surface Ligand Engineering for CsPbBr3Quantum Dots Aiming at Aggregation Suppression and Amplified Spontaneous Emission Improvement

In recent years, it has been reported that using ligands modification to passivate the surface is one reasonable approach to improve the optical properties and stability of perovskite quantum dots (QDs). However, a simple and effective way to diminish the aggregation phenomenon of perovskite QDs is still challenging. Herein, a ligand-engineering strategy is adopted to fabricate CsPbBr(3)QDs by applying a shorter capping ligand octylamine (OLA) to replace the commonly used long ligand oleylamine (OAm). After the ligand modification, the photoluminescence quantum yield of CsPbBr(3)QDs is enhanced from 62.4% to 91.3%. No aggregation or degradation phenomenon can be observed in solution even after being exposed to the air for 100 days. Moreover, the OLA-CsPbBr(3)QDs film can keep 96.8% of initial photoluminescence intensity even when stored under ambient condition for 5 weeks. Furthermore, the stimulated emission performance is investigated in terms of amplified spontaneous emission (ASE), and the ASE threshold of OLA-CsPbBr(3)QDs is only 24% of the OAm-CsPbBr(3)QDs threshold, and the ASE photostability is also enhanced. All the results suggest that the OLA ligand modification is an available strategy to improve the properties of CsPbBr(3)QDs and to shed light on the potential practical applications for photoelectric devices.