Synergistic Ligand Pair Exchange Strategy in Perovskite Quantum Dots to Enhance Photoelectric Properties and Stability

Perovskite quantum dots (PeQDs) have attracted significant attention as research materials due to their adjustable bandgaps, high photoluminescence quantum yield, and excellent color purity. However, conventional surface ligands often suffer from weak coordination capacity and low conductivity, adversely affecting the stability and photoelectric properties of PeQDs. In this study, a synergistic ligand pair exchange strategy is introduced to enhance the properties of pristine CsPbBr₃ PeQDs. By sequentially incorporating α-methyl-4-fluoro-benzylamine and p-toluenesulfonic acid, the original OA/OAm ligand pair is successfully replaced, efficiently passivating the A- and X-site vacancies. The modified CsPbBr₃ PeQDs demonstrate notable improvements in photoluminescence intensity and stability when exposed to UV light, high temperatures, and water immersion. Furthermore, this treatment approach is applicable to CsPbI₃ and mixed-halogen PeQDs. A high-performance photodetector fabricated from these treated CsPbBr₃ QDs showcases a responsivity of 3.9 mA W⁻¹ and a detectivity of 2.0 × 10¹⁰ Jones, representing a 6-fold enhancement over untreated counterparts. Also, devices based on treated CsPbBr₃ QDs show potential in optical communications, effectively illustrating encryption and decryption processes. This synergetic ligand pair exchange strategy offers a promising avenue for the broader application of PeQDs in optoelectronics devices and circuits.