Quantifying the Elemental Distribution in Solar Cells from X-Ray Fluorescence Measurements with Multiple Detector Modules

Abstract

Within the analysis of solar cells with multi-modal X-ray microscopy, X-ray fluorescence (XRF) measurements have become a reliable source for evaluating elemental distributions. While XRF measurements can unveil the elemental distribution at unparalleled sensitivity and spatial resolution, the quantitative analysis is challenged by effects such as self-absorption and further complicated by the inclusion of multiple detector modules. Here, we showcase the exemplary analysis of XRF spectra obtained from a Cu(In, Ga)Se <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solar cell utilizing four detector modules. After cataloging typical features found in XRF spectra, we demonstrate the inclusion of detector modules with individual absorption correction. This results in quantitative stoichiometric ratios of the critical absorber elements Cu, In, and Ga that are in good agreement with the nominal ratios. These results are particularly relevant in view of future measurements at diffraction-limited synchrotron beamlines: in order to profit from the boost of nano-focused photon flux, XRF measurements will require multiple detector modules, for which we demonstrate an approach of quantitative analysis.