Influence of deposition potential and substrate characteristics on the photovoltaic conversion efficiency of p-SnS absorbing layers

Abstract

In this study, thin films of tin sulfide (SnS) deposited on indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO) substrates using Sn-S electrodeposition were systematically investigated. Notably, a novel non-toxic sulfur precursor was employed, emphasizing its role in ensuring the safety and environmental friendliness of the synthesis process. The research was focused on the influence of deposition potential and substrate type on the physical properties of SnS films. X-ray diffraction (XRD) analysis disclosed distinct peaks corresponding to orthorhombic SnS phase planes (101), (111), and (040). Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) revealed a uniform distribution of essential components, particularly notable at −0.7 V on ITO and −0.9 V on FTO substrates. Raman spectroscopy identified characteristic peaks at 90 cm−1 and 222 cm−1. UV–visible spectrophotometry highlighted alterations in the optical band gap of SnS films on ITO (1.93 eV to 1.57 eV) and FTO (2.13 eV to 1.98 eV). Mott-Schottky analysis revealed consistent p-type conductivity behavior in the SnS layer, while both ITO and FTO layers exhibited n-type conductivity behavior. This characterization underscores the distinct electronic properties of each layer, providing valuable insights for the development of advanced optoelectronic devices. Electrochemical Impedance Spectroscopy (EIS) results demonstrated a significant reduction in charge transfer resistance (Rct) of SnS films on ITO at −0.7 V. The solar cell efficiency of the SnS absorber layer reached 2.2% on ITO at −0.7 V, contrasting with 1.47% on FTO at −0.9 V.