Investigating the impact of copper precursors on the photovoltaic performance of Cu2SnS3 thin film-based solar cells toward an enhanced power conversion efficiency of 9.85%

In this study, we explored the effect of copper precursors on the photovoltaic properties of eco-friendly and earthabundant Cu2SnS3 (CTS) thin films deposited by the easy and economical SILAR method. Comprehensive characterization revealed the critical role of copper precursors in shaping the structural, morphological, optical, and electrical properties of CTS films. XRD, Raman spectroscopy and HRTEM revealed the successful formation of the Cu2SnS3 phase, with the coexistence of the tetragonal and cubic structures. SEM images demonstrated considerable impact of the copper precursor on the morphology of the CTS films, revealing good surface compactness when using the acetate precursor. A uniform Cu-Sn-S distribution with a value close to the ideal stoichiometry of 2:1:3 of Cu2SnS3 is verified by EDX. The direct optical bandgap energy showed a correlation with the copper precursor, giving values between 1.37 eV and 1.45 eV, ideal for use as absorber layers. Electrical Hall effect measurements carried out on the grown CTS layers exhibited a Hall mobility of 0.38 cm2/V.s for copper sulfate and 0.592 cm2/V.s for chloride and 3.56 cm2/Vs for acetate with p-type conductivity and a carrier concentration between 2.688 x 1021cm-3 and 6.672 x 1021 cm-3. Furthermore, the photovoltaic performance of solar cells based on CTS thin films, as prepared in this study, was measured using the SCAPS-1D simulator. The solar cell-based CTS films fabricated using the copper acetate precursor achieved an impressive power conversion efficiency (PCE) of 9.85 % and an improved open-circuit voltage (Voc) of 739.85 mV. These results highlight an innovative and cost-effective solution for the production of scalable solar cells using copper acetate as a precursor in the SILAR synthesis of CTS thin films, avoiding the high costs and technical challenges associated with vacuum deposition techniques.