Next, the color proxy is extended to bulk samples in addition to perovskite film samples. In this case, device efficiency is not a direct usable metric, therefore changes in crystal structure are used to elucidate the extent of degradation. Powder XRD analysis was performed before and after longitudinal aging tests. Samples were aged for 150 hours at 0.15 Sun, 85℃ and 85% RH. As with thin film testing, image capture was performed at the visible wavelengths, with analysis of RGB channels.