Solution Phase Fabrication of Photoactive Cu2BaSnS4 Thin Films for Solar Energy Harvesting

The quaternary Cu2BaSnS4 (CBTS) is a new class of compound-semiconducting material, recently, emerging as one of the promising materials in the field of photovoltaics and solar water splitting applications. The difference in the electronic properties between the cations in the CBTS structure discourages the antisite defect formation and associated band tailing seen in kesterite Cu2ZnSn(S,Se)4 (CZTSSe) absorber. The direct bandgap, strong optical absorption coefficient (> 104 cm−1), and usage of earth-abundant and non-toxic elements for the growth of thin film make it alternative to kesterite CZTSSe. In this work, we have developed CBTS thin film by a simple and cost-effective successive ionic layer adsorption and reaction (SILAR) method with a varied thickness on soda–lime glass and molybdenum-coated soda–lime glass. The optical, structural, and morphological properties were investigated, and photoresponse of the material has been characterized. Raman spectroscopy results show two vibrational peaks with a distinct peak at 341 cm−1 and also XRD showing a dominant peak for (014) plane confirming the formation of pure CBTS phase. The electrical characterization of the solution-deposited CBTS films reveals the photo-absorbing properties of the materials and predicts the promising application of these materials in the photovoltaic devices.