Sb₂S₃ Thin-Film Solar Cells Fabricated from an Antimony Ethyl Xanthate Based Precursor in Air

The rapidly expanding demand for photovoltaics (PVs) requires stable, quick, and easy to manufacture solar cells based on socioeconomically and ecologically viable earth-abundant resources. Sb₂S₃ has been a potential candidate for solar PVs and the efficiency of planar Sb₂S₃ thin-film solar cells has witnessed a reasonable rise from 5.77% in 2014 to 8% in 2022. Herein, the aim is to bring new insight into Sb₂S₃ solar cell research by investigating how the bulk and surface properties of the Sb₂S₃ absorber and the current-voltage and deep-level defect characteristics of solar cells based on these films are affected by the ultrasonic spray pyrolysis deposition temperature and the molar ratio of thiourea to SbEX in solution. The properties of the Sb₂S₃ absorber are characterized by bulk- and surface-sensitive methods. Solar cells are characterized by temperature-dependent current-voltage, external quantum efficiency, and deep-level transient spectroscopy measurements. In this paper, the first thin-film solar cells based on a planar Sb₂S₃ absorber grown from antimony ethyl xanthate (SbEX) by ultrasonic spray pyrolysis in air are demonstrated. Devices based on the Sb₂S₃ absorber grown at 200 °C, especially from a solution of thiourea and SbEX in a molar ratio of 4.5, perform the best by virtue of suppressed surface oxidation of Sb₂S₃, favorable band alignment, Sb-vacancy concentration, a continuous film morphology, and a suitable film thickness of 75 nm, achieving up to 4.1% power conversion efficiency, which is the best efficiency to date for planar Sb₂S₃ solar cells grown from xanthate-based precursors. Our findings highlight the importance of developing synthesis conditions to achieve the best solar cell device performance for an Sb₂S₃ absorber layer pertaining to the chosen deposition method, experimental setup, and precursors.