Synthesis and purification of carbon dots from fluorescent precursors as colorant for fluorescent ink

Blue-emissive carbon dots (CDs) were synthesized using tetraphenylethylene and benzothiadiazole carbaldehyde via solvothermal method. The as-synthesized solvothermal product was purified via column chromatography technique. Among all eluted fractions, the third fraction demonstrated blue fluorescence (λ_em = 490 nm). TEM imaging showed quasi-spherical CDs with polycrystalline nature having diameters ranging between 5 and 35 nm. Upon addition of water to the CDs dispersion the precipitate formed showed prominent blue fluorescence (λ_em = 450 nm). Further, the CDs were dispersed in hydroxyethyl cellulose, a water-soluble binder to formulate a water-based ink and was printed on UV dull paper by screen printing technique. The print proofs displayed prominent blue fluorescence (λ_em = 450 nm) with good adherence and photostability.