Offering new potential among stable inorganic photovoltaic absorbers for hybrid solar cells, Sb₂S₃ has been used to coat planar or mesoporous TiO₂ [1–4]. Chemical Spray Pyrolysis is an economical method for producing thin oxide- or sulphide layers. The technique is scalable with little cost and is technically a simple method with no need for vacuum or inert gas supply. Spray has been recently used to deposit Sb₂S₃ [1,3] resulting in a 1.3%-efficient planar 1cm² cell [1] but also 6.6%-efficient perovskite-based 1.5 cm² mesoporous cells [4]. We develop a hybrid cell with TiO₂ and Sb₂S₃ layers deposited by spray coating that uses ultrasonically generated mist of alcohol-dissolved precursor chemicals. The TiO₂ followed by Sb₂S₃ are grown in a simple fume hood, in air, onto an ITO substrate at 200-250°C. We vary the ratio of sulphur source (thiourea) to antimony source (SbCl3) in the spray solution to inhibit formation of oxides and suppress sulphur-containing impurities. We optimise a two-step process for production of the Sb₂S₃ layer with the goal to develop a conformal coating on a nanostructured substrate, candidate being ZnO nanorod layer by electrochemical, spray, or chemical bath method. The as-deposited Sb₂S₃ layers are heat-treated up to 30 minutes at deposition temperatures, or, at 300°C for 5 minutes in vacuum, N₂ or H₂S environment. The morphology, chemical composition, structural and optical properties of the  Sb₂S₃ layers are characterized by SEM, Raman, XRD and UV-Vis methods, respectively. Heat treatment of Sb₂S₃ thin layers in N₂, H₂S, and vacuum improved crystallinity, density and substrate coverage. Additionally, heat treatment in H₂S improved the stoichiometry of the Sb₂S₃ layers. We report single-phase crystalline Sb₂S₃ films with a band-gap of 1.7 eV, as grown by the low-cost ultrasonic spray pyrolysis followed by post-deposition heat-treatment. The Sb₂S₃ films were tested in planar solar cells using glass/ITO/TiO2/Sb2S3/P3HT/Au structure, with PV evaluation of the photovoltaic output by I-V curve and EQE measurements. With a 3.3% conversion efficiency from an active area of 0.9 cm², and 5.5% from a cell with a small dot contact, both under solar simulator, the result is competitive with predicted improvement for the efficiency and the cell area.

1.Kärber et.al. Beilstein J. Nanotechnol. 2016, 7, 1662–73.
2.Gödel et.al. Chem. Commun. 2015, 51, 8640.
3.Parize et.al. J. Phys. Chem. C. 2017, 121 (18), 9672–80.
4.Bishop et. al. Sci. Rep. 2017, 7(1), 7962.