Aggregation-Induced White Light Emission and Solvent-Induced Dual Mode Multi-Analyte Sensing by Highly Crystalline Single Component Derived N, S Co-Doped Carbon Nanodots

Abstract

Recently, carbon nanodots (CNDs), the zero-dimensional carbon nanomaterials, have attracted immense research interest. Besides inherent traits like biocompatibility, eco-friendliness, electron mobility, and water-soluble nature, CNDs, as a green material with inherent luminescence, have grabbed a lot of attention and have opened up applications in more real-world contexts. In the present study, we project methionine-derived N, S co-doped CNDs as an efficient candidate for white-light-emitting diode (WLED) applications and dual-mode multianalyte sensing, based on their covetable fluorescence. Here, a scalable, dry white-light-emitting solid material is achieved from the aqueous dispersion of CNDs through freeze-drying process, without encountering the usual hurdles that are met with in solid-state CND systems, such as aggregation-caused quenching (ACQ) in luminescence, incomplete dryness, and low yield. The present system stands distinct, as warm white light is achieved by simply integrating the white light emitting single-component derived CND powder with near ultraviolet LED chips (370 nm) without ACQ resistors or additional phosphors. WLEDs with a low correlated color temperature of 3762 K and a moderately high color rendering index, which are suitable for interior lighting, are achieved. Along with the optoelectronic application, the system is potent enough to respond to the presence of two biologically significant species, folic acid and Fe3+ ions, through a dual-mode operation, viz, fluorescence turn-on and turn-off strategies, respectively. Excellent selectivity from a galaxy of 34 analytes is noted for the system, with attractive detection limits of 0.709 and 14.08 μM for folic acid and ferric ion, in the respective order. A detailed investigation of the mechanisms proves the inner filter effect (IFE) and Forster resonance energy transfer-mediated fluorescence enhancement and IFE-mediated quenching effect, operating here.