Ultra-stable water-dispersive perovskite QDs encapsulated by triple siloxane coupling agent system with different hydrophilic/ hydrophobic properties

Driven by the instability of perovskite quantum dots (PQDs), different encapsulation techniques have been used to improve their stability. However, further improvements in the extreme environmental tolerance and polar solvent solubility of PQDs are required to deliver a broader application. How to balance the stability and dispersibility of PQDs in polar solvents is probably the most difficult problem to alleviate in this area. Herein, we promote a facile strategy to construct ultra-stable water-dispersive silica-encapsulated PQDs (PQDs@SiO2-d) by in situ co-hydrolyzing a specially designed triple silane-coupling agent system based on (3-aminopropyl)triethoxysilane (APTES), superhydrophobic perfluorooctyltrimethoxysilane (PFMS), and hydrophilic siloxane terminated polyethylene glycol (Si-PEG). Specifically, protonated APTES (APTES+, from HBr) and APTES are used as alternatives to oleic acid/oleylamine (OA/OAm) ligands, PFMS imparts an excellent resistance to harsh environments, and hydrophilic Si-PEG improves the dispersibility of the resulting material. The PQDs@SiO2-d retains a high PLQY (93%) and presents great dispersibility and stability towards polar solvents. More importantly, the PQDs@SiO2-d can retain a 70% PL intensity after long-term storage under acidic (pH = 1), alkaline (pH = 14), and ionic conditions (PBS buffer solution) for 24 h by regulating the surface hydrophobic and hydrophilic properties of the PQDs. Profiting from these superior properties, the PQDs@SiO2-d can be used directly as a cellular labeling agent for cell imaging.