Carbon Dots With Aggregation‐Dependent Photoluminescence and Application in Rewritable Water‐Jet Printing

ABSTRACT Carbon dots (CDs) have garnered significant attention for their excellent and versatile optical properties. Nevertheless, the influence of aggregation states on the photophysical properties of CDs has not yet been systematically elucidated. Herein, we present a systematic investigation into the aggregation‐dependent photophysical behavior of CDs with a Si–O–Si‐encapsulated luminescent carbon core and surface long‐chain fatty amines. This study reveals two distinct pathways for emission modulation: (1) achieving concentration‐dependent photoluminescence for CDs, spanning from green ( λ em = 527 nm) to deep red ( λ em = 672 nm); and (2) inducing the self‐assembly of CDs into size‐tunable nano‐ to micro‐scale spherical structures in a poor solvent, which exhibit aggregation‐induced emission with a maximum photoluminescence quantum yield of 87.6%. This unique dual‐mode aggregation‐dependent photoluminescence enables the successful application of CDs in rewritable water‑jet printing, highlighting their strong potential for practical uses.