Figure 9.
The image includes a graph consisting of four plots arranged in two rows and two columns. Each plot represents the relationship between the variable a h v squared, scaled by 10 to the power of 9, in electron volts per square centimetre on the vertical axis and photon energy in electron volts on the horizontal axis. The top left plot, labelled C Z T S A D, features data points represented by open black circles, while a solid line indicates a fitted trend. The top right plot, labelled C Z T S 340, displays similar data points in open red circles. The bottom left plot, labelled C Z T S 360, uses open pink circles for its data points, and the bottom right plot, C Z T S 380, shows open blue circles for its data points. Each plot has a trend line plotted in black, and the axes are consistently scaled across all four graphs. The overall arrangement allows for comparison between different C Z T S materials across the photon energy spectrum.Optical bandgap of all CZTS thin films determined by Tauc method