Optimizing antimony trisulfide thin films: enhanced structural and optoelectronic properties via post-annealing in sulfur atmosphere

Antimony trisulfide (Sb₂S₃) is a promising material for photoabsorption due to its high absorption coefficient, low toxicity, and abundance in nature. However, various stoichiometric and crystalline defects have limited its practical applications. Herein, highly crystalline Sb₂S₃ thin films are fabricated via thermal evaporation and subsequent annealing in a sulfur atmosphere at different temperatures. The analyses of X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and optical properties reveal highly crystalline Sb₂S₃ thin films. The films showed reduced stoichiometric and crystal defects, while also displyaing enhanced optical and morphological properties. The improvement in the physical properties of the Sb₂S₃ thin films is attributed to the filling of sulfur deficiencies by extra sulfur vapors present during the thermal annealing process. Moreover, annealing the obtained Sb₂S₃ samples at different temperatures (ranging from 250 °C to 300 °C) reveals that the Sb₂S₃ films exhibit improved physical properties at 300 °C, which is considered to be the optimal annealing temperature. Our findings open up a pathway for the fabrication of highly crystalline Sb₂S₃ thin films, which could lead to the development of efficient optoelectronic devices.