In this section we present STXM analysis of a FIB lamella of FAMAPbI3. The device structure used in this synthesis was for photovoltaic applications and not specifically for STXM measurements. Hence the layers were of standard thicknesses and not thicker as recommended earlier. Hangoma et al. where they proposed that moisture could pass through the PCBM layer and could form MAI/HI. We assume that in our case where the whole layer was exposed to atmosphere (although momentarily) and this argument cannot hold. Further detailed analysis is necessary to understand these observations. We have presented experimental results showing the possibilities of detecting chemical functionalities and accessing the chemical homogeneity of the perovskite layer. It is important to note that while we have shown STXM studies of the active layer only, it is obvious that this technique can be extended to detailed studies of other device layers and interfaces as well.