Purity and crystallinity of microwave synthesized antimony sulfide microrods

Antimony sulfide (Sb₂S₃) is a promising semiconductor material for solar cell applications. In this work, microrods of Sb₂S₃ were synthesized by microwave heating with different sulfur sources, solvents, temperature, heating rate, power, and solution concentration. It was found that 90% of stoichiometric Sb₂S₃ can be obtained with thiourea (TU) or thioacetamide (TA) as sulfur sources and that their optical band gap values were within the range of 1.59–1.60 eV. The most crystalline Sb₂S₃ were obtained by using TU. The morphology of the Sb₂S₃ with TU the individual rods were exhibited, whereas rods bundles appeared in TA-based products. The solvents were ethylene glycol (EG) and dimethylformamide (DMF). EG generates more heat than DMF during the microwave synthesis. As a result, the Sb₂S₃ obtained with EG contained a larger percentage of oxygen and smaller crystal sizes compared to those from DMF. On the other hand, the length and diameter of Sb₂S₃ microrods can be increased by applying higher heating power although the crystal size did not change at all. In summary, pure and highly crystalline Sb₂S₃ microrods of 6–10 μm long and 330–850 nm in diameter can be obtained by the microwave method with a careful selection of chemical and thermodynamic parameters of the synthesis.