Fabrication and Characterization of Novel 2SSS CIGS Thin Film Solar Cells for Large-Scale Manufacturing

A novel 2SSS (2 Step Solid Selenization) CIGS (Cu, In, Ga, Se) thin film solar cell recipe was developed which can be a replacement to the conventional co-deposition process usually employed for large-scale manufacturing. The co-deposition procedure is faced with multiple problems such as selenium incorporation, effective gallium incorporation in the absorber. It is a 2-step proprietary procedure with better control over growth mechanisms and material utilization for the absorber layer for the CIGS thin film solar cells. It makes use of solid selenium source as preferred by manufacturers. Each step of the 2-step procedure was dealt with separately for stoichiometric analysis and interesting trade-offs between materials such as gallium, indium and selenium was found. Solar cells with this proprietary absorber were fabricated on soda lime glass substrates. Results of the solar cells made with the 2SSS process matched with that of the co-deposition process with the quantum efficiencies near 80% of the co-deposition cells. These experiments are going to serve as the test bed for the pilot line that is intended to be installed at USF\u27s research campus soon. The finished solar cells were characterized. The scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were some of the important tools during the analysis of stoichiometry and structural properties. The device performances were measured with the help of current-voltage (I-V) testing and quantum efficiency (QE) measurements