Low‐Temperature Synthesis of Solid‐State Fluorescent Carbonized Polymer Dots With an Ultra‐Broad Color Gamut From Violet to Near‐Infrared

Carbonized polymer dots (CPDs) with efficient and color‐tunable solid‐state fluorescence (SSF) are highly desirable for applications in solid‐state lighting and multicolor displays. However, their practical employment is hindered by aggregation‐caused photoluminescence (PL) quenching, limited tunability of energy levels, high synthesis temperatures, and low production yields. Herein, we report a low‐temperature (120–140°C) Schiff‐base reaction‐mediated strategy to fabricate CPDs with efficient and tunable SSF across the full violet‐to‐near‐infrared (NIR) spectrum for the first time. The synthesis proceeds via a solvent‐free reaction under ambient‐pressure conditions, followed by facile post‐treatment procedures, enabling reliable production on a hundred‑gram scale. Combined experimental and computational analyses reveal that the continuous emission redshift originates from a gradual reduction in energy levels, which correlates with an increased surface density of salicylaldehyde (SA) ligands and enhanced interparticle self‐assembly. The robust SSF performance arises from intra‐ and intermolecular hydrogen‐bonding networks within the aggregated CPDs, which effectively suppress nonradiative decay. Based on their broadly tunable SSF properties and excellent photostability, these CPDs have been successfully demonstrated in light‐emitting diodes (LEDs), three‐dimensional luminescent artwork, and latent fingerprint visualization.