Boosting the Efficiency of SnS Solar Cells Through Reactively Sputter-Deposited Ag-Nanostructured Layer/SnO₂ Film at Glancing Angles

The present study aims at analyzing the impact of new silver (Ag)/SnO₂ thin-film structures, as alternative buffer layers, and graded bandgap (GBG) SnS absorber material on the photovoltaic properties of eco-friendly SnS thin-film solar cells (TFSCs). In this regard, structural, optical, and electrical characteristics of ultra-thin Ag/SnO₂ bilayer structures were experimentally investigated using combined GLancing Angle Deposition (GLAD) and DC sputtering deposition techniques. The deposition angles of the particle flux were kept at 0° (planar) and 80° (oblique) during the DC sputtering deposition process. The influence of the Ag ultrathin top film and the deposition angles on the Ag/SnO₂ buffer layer characteristics is investigated, where structure morphological and optoelectronic characterizations were performed using SEM, XRD, and UV–Visible spectroscopy measurements. The deposited ultra-thin Ag/SnO₂ structures for different deposition angles showed Ag nanostructured layer (Ag-NL) with nanoparticles-like shape for oblique deposition. This demonstrates its potential application as an alternative electron transport layer (ETL) for efficient eco-friendly TFSCs. In this context, Ag-NL/SnO₂/GBG-SnSSe solar cells were studied using the elaborated ETL structure. The recorded efficiency of Ag-NL/SnO₂/GBG-SnSSe/Mo TFSC structure could reach 9.3%, showing a significant enhancement over CdS/SnS solar cells (4.4%). Moreover, it is demonstrated that the use of graded bandgap SnSSe as an absorber layer can provide a higher efficiency than single SnS-based devices. These results indicate that the proposed solar cell structure is suitable for developing efficient eco-friendly SnS solar cells.