Facile Post‐Processing Approach to Modulate Fluorescent Properties and New Matrix‐Assisted Method to Achieve Solid‐State Luminescence of CDs Based on CTAB Surfactant

Abstract To realize the practical application of carbon dots (CDs), it is crucial to devise straightforward techniques that can finely modulate the fluorescent properties of CDs. Apart from that, it is imperative to weaken the aggregation‐caused quenching (ACQ) effect, which poses a significant challenge to the utilization of solid‐state CDs. In this work, three CDs named as CDs‐1, CDs‐2, and CDs‐3 are synthesized, and the fluorescence tuning of these CDs is successfully realized, assisted by cetyltrimethylammonium bromide (CTAB) surfactant, because its unique molecular structure is conducive in bolstering fluorescence intensity and adjusting emission wavelength. Furthermore, the luminescence of solid‐state CDs is successfully achieved by employing CTAB as substrate in the matrix‐assisted synthesis of composites CDs‐1@CTAB, CDs‐2@CTAB, and CDs‐3@CTAB. Notably, the photoluminescence quantum yield (PLQY) of CDs‐2@CTAB reaches an impressive value as high as 79.31%, surpassing the value of 70.29% obtained by pristine CDs‐2. The experimental results reveal that CDs@CTAB composites exhibit intriguing afterglow characteristics including room temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF). This work confirms the versatility of CDs and highlights the significance of surfactant‐assisted strategies in improving the performance of CDs.