Lighting Up AIEgen Emission in Solution by Grafting onto Colloidal Nanocrystal Surfaces

Aggregation-induced emission luminogens (termed AIEgens) have emerged as an important class of light-emitting materials with many potential applications. As implied by their names, AIEgens typically exhibit strong emission in the aggregated form for which the intramolecular motions that dissipate excited-state energy are inhibited. Here we demonstrate that AIEgens, using carboxylated tetraphenylethylene (TPE-CA) as an example, can exhibit strong emission in the solution after being grafted onto colloidal nanocrystal (NC) surfaces. Using ultrafast transient absorption spectroscopy, we found that the intramolecular motions of TPE-CAs were strongly suppressed, with rates retarded by 2 orders of magnitude, when they were grafted onto ZnS NCs. As a result, the emission quantum yield (QY) of TPE-CA-NC hybrids in solution was also enhanced by 2 orders of magnitude compared to free TPE-CA molecules in solution. This opens a new avenue for constructing multifunctional hybrid materials capitalizing on the emission of AIEgens. In addition, this methodology can be extended to suppress aggregation-caused quenching (ACQ) of ACQphores in the solid-state form.