The MULTIGRAPH project goal is research and development of innovative multifunctional composites based on properties of graphene and chalcogenide nanocrystals (quantum dots). The project is mainly focused on synthesis and investigation of non-toxic and heavy-metals-free nano-sized materials using relatively inexpensive approaches. Such composites could be used as a photosensitive layer in photovoltaics or active materials for super capacitors and batteries. The graphene has two interesting properties, i.e. a wide light spectrum absorption and high electronic conductivity. Despite the wide absorbing range of the spectra, the absorption ability is too low. Therefore, graphene can be combined with chalcogenide nanocrystals, which possess a significantly higher absorption ability in a certain spectrum areas. The compound absorbing spectrum range is determined not only by the nature of the nanocrystals but also by their particle size.
The proposed study lays on the core hypothesis that shrinking crystal size to less than Bohr radius induce a quantum confinement effect, which leads to larger surface-to-volume, higher tunability of the physicochemical properties and easer functionalization. Decreasing or increasing the QDs size leads to increase or decrease, respectively, in the energy gap which alternates their absorption spectra and correspondingly shifts their emission wavelength toward blue or red spectral regions. The smaller particle size also contributes for faster ions transfer during electrochemical intercalation or de-intercalation in/out the respective particle, processes that occur in batteries and hybrid supercaps. The graphene is a perfect candidate for a substrate for of the quantum dots due to its high electronic conductivity, chemical resistance, photosensitivity, mechanical stiffness, strength and elasticity.
