Bulk crystals have a smaller surface-area-to-volume ratio than thin films. This means that degradation observed via optical change occurs at the surface of the sample but may not be indicative of subsurface structural change when the crystals are opaque. To address this limitation, crystals were ground and spread thinly across filter paper sample holders to ensure uniform degradation across the volume of the samples and increase the kinetics of degradation. The complete reduction in peak intensity in the [CHMA][PbI4] crystals (Figure ) shows that Bragg's Law no longer holds; the samples are no longer crystalline after the degradation test. In the MAPbI3 samples, the shifts in peak intensity illustrate the change to another crystalline structure (Figure ).