Carbon Dots as Cosensitizers in Dye-Sensitized Solar Cells and Fluorescence Chemosensors for 2,4,6-Trinitrophenol Detection

Carbon dots (CDs) are a unique class of fluorescent nanomaterials, whose emissions can be tuned by manipulating the reaction conditions of their formation. Herein, we report a facile solvothermal route for producing CDs with tunable properties by employing N,N-dimethylformamide as the solvent medium. Using completely green carbon sources, two types of CDs are synthesized: citric acid produces green emitting CDs (G-CDs) while gallic acid produces blue emitting CDs (B-CDs). The optical analysis of the G-CDs suggests their application as cosensitizers along with the N719 dye in dye-sensitized solar cells (DSSCs). Following this, the effect of G-CDs in DSSCs was studied and a photoconversion efficiency of 6.9% was extracted from the device. Meanwhile, the B-CDs produced from gallic acid are hydrophobic in nature and their blue-colored emission is quenched in the vicinity of 2,4,6-trinitriphenol in less than 1 min with a limit of detection of 0.75 μM.