Polar Organic Solvent-Tolerant Perovskite Nanocrystals Permanently Ligated with Polymer Hairs via Star-like Molecular Bottlebrush Trilobe Nanoreactors

The key to exploiting perovskite nanocrystals (NCs) for long-term practical use in optoelectronic materials and devices lies in the ability to access stable NCs. Herein, we report the crafting of hairy perovskite NCs with a set of markedly improved stabilities by capitalizing on rationally designed star-like molecular bottlebrush trilobes as nanoreactors. An intriguing star-like molecular bottlebrush trilobe, poly(2-hydroxyethyl methacrylate)-graft-(poly(acrylic acid)-block-partially cross-linked polystyrene (denoted PHEMA-g-(PAA-b-cPS)) is synthesized. Subsequently, it is employed as a polymeric nanoreactor to direct the growth of green-emitting all-inorganic perovskite CsPbBr₃ NCs intimately and stably tethered by partially cross-linked PS "hairs" (i.e., cPS-capped CsPbBr₃ NCs). The resulting CsPbBr₃ NCs exhibit an array of impressive stabilities against UV irradiation, moisture, heat, and water, due to permanently ligated hydrophobic cPS "hairs" on the surface of CsPbBr₃ NCs as a result of the original covalent bonding between PAA and cPS blocks. More importantly, cPS-capped CsPbBr₃ NCs manifest outstanding stability in various polar organic solvents. Such greatly improved stability can be attributed to the reduced surface defects enabled by the favorable interaction (i.e., coordination interaction and hydrogen bonding) between CsPbBr₃ NCs and polar solvents, which dominates over their dissolution by polar solvents. Such exceptional stabilities impart the use of cPS-capped CsPbBr₃ NCs as a selective probe for tracing the presence of Cl^-/I^- in polar organic solvents. The amphiphilic nonlinear block copolymer nanoreactor strategy can afford easy access to stable perovskite NCs of interest with controlled compositions and surface chemistry. They may find applications in solar cells, LEDs, photodetectors, lasers, bioimaging, biosensors, etc.