VOC-losses across the band gap: Insights from a high-throughput inline process for CIGS solar cells

Big sets of experimental data are key to assess statistical device performance and to distill underlying trends. This insight, in turn, can then be used to improve on the fabrication process. We here describe a standardized and optimized inline fabrication process and present a statistical analysis of tens of thousands of cells with chalcopyrite-type Cu(In,Ga)Se₂ absorber. The large number of samples allows us to point out where Ag alloying into the absorber offers improvements, and how it couples with compositional and optoelectronic properties. Solar cell parameters as a function of chemical composition of the absorber highlight the importance of fill factor on overall cell performance. Finally, we calculate losses in open-circuit voltage as a function of band gap energy and show that radiative losses can be reduced by increasing the amount of Cu and/or Ag.