Conjugate area-controlled synthesis of multiple-color carbon dots and application in sensors and optoelectronic devices

During the heretofore several years, Carbon dots (CDs) have achieved the widely used in fluorescence sensing, optoelectronics and bio imaging owing to their distinctive photoluminescence attribute. Here, CDs with bule to red emission were prepared by solvent heat treatment of phenol-derived with regulation the reaction time in the synthetic system, and their fluorescence spectra ranged from 450 ∼ 650 nm. Characterization through variety of methods and density functional theory calculations clearly demonstrates that the achieve stable long-wavelength emission caused in solvent is mainly due to the increase in conjugate area and oxygen elements of CDs. Importantly, conjugate area and oxidation degree can affect the level of HOMO-LUMO, further changing the band gap leading to fluorescent red-shift. Because of their excellent photoluminescent properties, we examined the performance in detection of non-metal ions by green and yellow-color CDs. The results show that they have high accuracy and rapid reaction to ClO− within the scope of 0 ∼ 50 μM and 4 ∼ 44 μM, with response limits are 31.1 nM and 56.5 nM, respectively. Moreover, we also prepared CDs/PMMA films and CDs/epoxy resin films with highly transparent and stability. Subsequently, the white-light emission diodes (0.32, 0.31; ClE coordinate) was obtained through mixing CDs in a certain proportion. This study provides a novel platform for fluorescence sensing of multi-color emission CDs, and provides strong potential for new optoelectronic equipment.