We study the mechanism of surface adsorption of organic dyes on graphene, and successive exfoliation in water of these dye-functionalized graphene sheets. A systematic, comparative study is performed on pyrenes functionalized with an increasing number of sulfonic groups. By combining experimental and modeling investigations, we find an unambiguous correlation between the graphene–dye interaction energy, the molecular structure and the amount of graphene flakes solubilized. The results obtained indicate that the molecular dipole is not important per se, but because it facilitates adsorption on graphene by a “sliding” mechanism of the molecule into the solvent layer, facilitating the lateral displacement of the water molecules collocated between the aromatic cores of the dye and graphene. While a large dipole and molecular asymmetry promote the adsorption of the molecule on graphene, the stability and pH response of the suspensions obtained depend on colloidal stabilization, with no significant influence of molecular charging and dipole.

We used automatized image processing of AFM data to measure, one by one, the exact shape and size of thousands of nanosheets obtained by exfoliation of a 2D-material, boron nitride.

Thermodynamics drive the sonication-free spontaneous dissolution of a KC₈ graphite intercalation compound in N-methyl-pyrrolidinone and subsequent obtention of graphene solutions at 0.7 mg ml⁻¹. Reduction potential of graphene has been measured at +22 mV vs. SCE.

Quantum dots are of growing interest as emissive materials in light-emitting devices. Here first we report the formation of highly luminescent organic capped colloidal cadmium sulfide (CdS) nanoparticles having the highest photoluminescence quantum yield of 69% in solutions and 34% in neat thin films in the near-infrared range. Second, we also show efficient electroluminescence in the near-infrared from solution processed hybrid light emitting diodes (LEDs) based on such colloidal CdS quantum dots embedded in an organic semiconductor matrix forming a nanocomposite active layer. We also discuss the device structure and role of the doped active layer in efficiency improvement. With optimized active layer thickness and concentration of QDs, the device exhibits an external electroluminescence quantum efficiency of 0.62% at a peak emission wavelength of 760 nm, providing a route to solution processable flexible light sources for biosensors and medicine.

Graphene oxide (GO) exfoliated sheets were used as two dimensional platforms to covalently tether on their surface thousands of optically active quaterthiophene molecules (T4), using an innovative microwave-assisted silanization reaction. This method allowed to perform GO functionalization in one-step, under mild conditions in a few tens of minutes rather than days. The hybrid GOT4 could be processed in either H₂O or apolar organic solvents and deposited as single sheets, microplatelets or macroscopic membranes. Absorption/emission spectroscopy reveals that GOT4 combines limited T4-T4 interactions with strong T4-GO ones. These findings, combined with the ‘user-friendly’ engineering approach presented here, pave the way towards the bottom-up fabrication of new GO-based tailored materials for electronics, sensors and biological applications.