Engineering Solid‐State Fluorescent Carbon Dots with Aggregation‐Induced Emission by Fatty Amine Chains‐Regulated Charge Transfer and π‐π Stacking

Abstract Carbon dots (CDs) are an encouraging green luminescent material; however, the aggregation‐caused quenching (ACQ) effect poses a significant limitation for their use in solid‐state devices. By adjusting precursor fatty amine chains, this paper synthesized four solid‐state emissive CDs with aggregation‐induced emission (AIE) properties (Lx‐CDs). When water is introduced, the generation of Lx‐CDs aggregates creates the switching off of the carbon‐core emission (blue) in acetic acid solution and the switching on of the surface‐state emission (orange). Results demonstrate that the disulfide bond and fatty amine chain structures allow considerable inhibition in the distance of aromatic skeletons, causing the aggregation‐state emission, and the multiple interactions in aggregates can reduce the non‐radiative processes benefiting the AIE. Besides, the fast and slow fluorescence species can be confirmed to correspond to the emission paths of carbon‐core and surface‐state, respectively. The solid‐state emission wavelength, photoluminescence quantum yield (PLQY), and AIE strength can be engineered by the fatty amine chain regulated charge transfer and π‐π stacking. This study not only reveals the intrinsic mechanism of carbon‐core and surface‐state luminescence dynamics in AIE CDs but also provides a method for controlling fluorescence wavelength and enhancing the emission of aggregated particles using precursor fatty amine chain length.