N-doped carbon dots with tunable emission for multifaceted application: solvatochromism, moisture sensing, pH sensing, and solid state multicolor lighting

Publication date: Available online 13 May 2019Source: Sensors and Actuators B: ChemicalAuthor(s): Md Moniruzzaman, Jongsung KimAbstractNovel N-doped green-emitting carbon dots (N-GCDs) that were responsive to various external stimuli and had high quantum yields (QYs) for multifaceted applications were synthesized from β-resorcylic acid and ethylenediamine using a hydrothermal process followed by a reflux method. The QYs of the N-GCDs were in the range of 17.36%–48.4% and were associated with different photoluminescent color emission in different solvents. Interestingly, the as-synthesized N-GCDs exhibited strict solvent polarity-dependent switchability (solvatochromism) and multicolor excitation-wavelength-independent emission in different solvents. Sensing of an analyte based on the switching of the photoluminescence (PL) emission maxima (λmax) is always preferred over that based on fluorescence quenching to avoid complexity and confusion regarding the initial fluorescence intensity (I0) and thus make the sensing process simple, rapid, ordered, and reliable. The N-GCDs exhibited blue emission in low-polarity organic solvents, but with the increase of the trace water content in the system, the PL emission peak gradually shifted to a higher wavelength (bathochromic shift) at a single-wavelength excitation. Thus, the N-GCDs are sensitive visual probes for the fluorescence detection of the trace water content in organic solvents without sophisticated processes. They also ind...
Source: Sensors and Actuators B: Chemical - Category: Chemistry Source Type: research