Copper zinc tin sulfide (CZTS) has long been seen as a potential alternative to CIGS in thin film production, as it is based on materials that are cheaper and more abundant. However, its conversion efficiency has lagged behind that of CIGS. The current record for CZTS stands 7.6% for a full sized solar cell, and 12.7% for a smaller research cell, compared with 22.3% for CIGS.
The team at Swansea University etched several samples of CZTS using a sodium sulfide solution. They then used Raman spectroscopy, a technique where samples are illuminated using a laser beam and viewed under a microscope, to observe the material’s performance.
“Raman spectroscopy is a powerful technique to identify a number of CZTS and secondary phases at the surface,” said a spokesperson for the research team. “Raman mapping could play a significant role in monitoring absorber film quality during industrial production.”
Further monitoring of photoluminescence showed that the etching process had improved the material’s performance. “These results help us to apply the most suitable etching in device fabrication of CZTS solar cells,” stated the team in a press release. “Future studies will focus on exploring links between Raman mapping and CZTS solar cell performance.”