In light of these issues, there is a critical need for quantitative non-destructive in situ/operando compatible techniques to measure OMIEC ionic composition and distribution. To this end, synchrotron radiation techniques (especially spectroscopy and scattering) present an attractive means of accomplishing both. X-ray fluorescence (XRF) spectroscopy has been performed in a wide range of elemental analyses, known for being fast, non-destructive, accurate, and is ideal for the quantitative analysis of low concentration elements in thin film samples. Common benchtop XRF instruments often use a fixed incident wavelength, which results in weak fluorescence intensity when the incident photon energy is far from the absorption edge of the target element. In synchrotron light sources, the accuracy of the analysis of the target element at the absorption edge of the element is further improved because of the high brilliance and tunable wavelength of the incident X-rays. Selection of known composition calibrant samples with similar geometry and elemental ratio to the sample of interest enables quantitative elemental analysis of OMIEC samples, and has allowed high precision determination of trace impurities in conjugate polymer based solar cells. Small angle X-ray scattering with synchrotron sources enables the probing of mesoscale structure. Significant work has been carried out to understand OMIEC as-cast structure, revealing the effect of additives and processing conditions on meso-scale structure, and meso-scale structure formation during film deposition. While in situ work has been reported on the electrochemical potential meso-scale structure in Li + transporting block copolymers for battery applications, there have been a noted absence of work reporting small angle scattering in other types of OMIECs exposed to application-relevant conditions in situ or ex situ.