Highly Emissive and Color-Tunable Perovskite Cross-linkers for Luminescent Polymer Networks

Emissive cross-linkers are of special interest for polymer science because of their ability to endow polymer networks with luminescent properties. Methylammonium lead halide perovskite nanoparticles (MAPbCl _xBr_{3- x} NPs) are extensively explored for optical and optoelectronic applications. In this work, MAPbCl _xBr_{3- x} NPs with cross-linkable and polymerizable ligands are successfully prepared as new emissive cross-linkers for polymer networks. Commercially available reagent 2-aminoethyl methacrylate hydrochloride (AMHCl) can act as a ligand to stabilize MAPbBr₃ NPs in solution. Compared with traditional ligands (oleic acid and oleylamine), AMHCl retains the architecture of perovskite effectively and affords polymerizable groups (vinyl) on the surface of perovskites. The as-prepared MAPbCl _xBr_{3- x} NPs can serve as cross-linkers in the radical polymerization of (meth)acrylates by UV-light to form polymer networks. Meanwhile, such cross-linkable emitters exhibit bright luminescence and color-tunability at room temperature, attributed by a unique halide exchange of perovskites between CH₃NH₃Br and AMHCl, which provides the polymer networks with varied emissive bands. These perovskite-crosslinked networks showed high air stability, water stability, and prominent photoluminescence quantum yields. On the basis of these excellent properties, white-light-emitting diodes were successfully fabricated from these perovskite-crosslinked composites with color-coordinate values at (0.316, 0.315), very close to the standard coordinates of white light. This work elucidates a new and convenient technique to convert nanocrystals into luminescent cross-linkers to build functional polymeric networks for technological applications.