Figure 2. Dispersion characteristics of TMD nanosheets in organic solvents.

(a) Absorbance spectra of PS-NH₂ (black), MoSe₂ dispersed with PS-NH₂ in toluene (blue) and MoSe₂ dispersed without PS-NH₂ in NMP (red). (b) Effect of the molecular weight of PS-NH₂ on the efficiency of the MoSe₂ dispersion in toluene characterized by the absorbance values of the dispersions at 800 nm. The initial concentrations of MoSe₂ and PS-NH₂ were kept constant at 10 mg ml⁻¹ and 1 mg ml⁻¹, respectively, for all of the molecular weights of PS-NH₂ evaluated. Increasing the molecular weight of PS-NH₂ leads to a decrease of the efficiency of the MoSe₂ dispersion. (c) Absorbance at a wavelength of 800 nm as a function of the MoSe₂ concentration in each solvent. The absorbance linearly increased with the amount of MoSe₂ following Lambert–Beer behaviour, which implies uniform dispersion of MoSe₂ without aggregation in all of the solvents. (d) Plots of the concentration of MoSe₂ as a function of the initial concentration of PS-NH₂ in different organic solvents. Yield of one to three layers (70%) of the exfoliated MoSe₂ nanosheets with PS-NH₂ as a function of the initial concentration of PS-NH₂ in different organic solvents are also shown. (e) Absorbance per cell length (proportional to the concentration of dispersed MoSe₂) of MoSe₂ dispersed in a range of solvents with a concentration of 3 mg ml⁻¹ of the different amine-terminated polymers. Note that PE-NH₂ was dissolved in hot toluene and xylene. For MoSe₂ dispersion in water with PEO-NH₂, sonication was applied for 2 h. (f) Absorbance spectra of the dispersions of different TMDs exfoliated in toluene with PS-NH₂. The absorbance spectra are vertically displaced for clarity.