Identification of Environmentally Friendly Solvents to Exfoliate and Stabilize the Dispersions of Antimony Sulfide Nanosheets for Optoelectronic Applications

Achieving dispersions of antimony sulfide (Sb 2 S 3 ) in environmentally friendly solvents is of paramount importance for safer and sustainable processing due to its wide range of applications. The efficacy of liquid-phase exfoliation (LPE) depends on the choice of solvents, and the determination of the Hansen solubility parameters (HSP) is crucial. In this work, employing the Hansen solubility sphere method, the HSP values of Sb 2 S 3 are determined to be 20.8, 10.8, and 13.4 MPa 1/2, which correspond to dispersive, polar, and hydrogen-bonding interactions, respectively. Environmentally friendly solvents, such as 2-butanol and isopropyl alcohol (IPA), have been identified as good solvents for exfoliation. Subsequently, the stability of the dispersions is investigated using an analytical centrifuge. Through the in situ visualization of transmission profiles and various stability parameters like the instability index, sedimentation velocity, and decay time constants, 2-butanol is found to have excellent dispersion stability. To further explain the observed stability, density functional theory (DFT) calculations are carried out. The adsorption energy of 2-butanol on the surface of Sb 2 S 3 is higher than that of IPA, leading to better solute–solvent interactions and, hence, better dispersion stability. Subsequently, the dispersions are utilized to fabricate thin films using the spray-coating method. The solution-processed Sb 2 S 3 photodetector exhibits an impressive responsivity of 68 mA/W, noise-equivalent power (NEP) of 0.3 pW/Hz –1/2, and detectivity of 2.4 × 10 11 Jones.