Conducting carbon quantum dots - a nascent nanomaterial

Herein, the conducting properties of poly(4-styrene sulphonate)-stabilized carbon quantum dots (PSS-CQDs) are reported. High-resolution transmission electron microscopy, Fourier transmission infrared spectroscopy and thermogravimetry were used to determine the size, crystalline nature and surface nature of PSS-CQDs. The material showed a strong emissive behavior. The fluorescence excitation spectra of the CQDs showed evidence of low lying energy states, which were responsible for the excitation-dependant fluorescence properties. The current-voltage (I-V) characteristics of individual PSS-CQDs coated on ITO were probed using the spreading resistance imaging mode of an atomic force microscope. The I-V data of individual PSS-CQDs exhibited a linear behaviour at low bias and a sudden jump in current value as the bias crossed zero voltage. Cyclic voltammetry (CV) was used to determine the band gap of the CQDs. I-V behaviour was interpreted using the CV data and fluorescence properties of PSS-CQDs. The study might lead to the development of cheap and green conducting nanomaterials for future applications.