Renewable energy
When it comes to energy production – such as solar cells, fuel cells or water splitting – an understanding of a material’s physiochemical properties is essential to efficient energy conversion. Excillum X-ray sources boost both throughput and resolution in X-ray based techniques including XRD, SAXS, XRF, XAS/XES, HAXPES and more, enabling researchers to gain deeper understanding of the relations between a material’s macroscopic performance and microscopic properties.
Application examples
Performance improvements of solar cells
In the laboratory at Meiji University, led by Professor Atsushi Ogura, the objective is to improve the performance of solar cells and electronics devices based on semiconductor nanotechnology. A significant improvement in material characterization capability was achieved when a Scienta Omicron HAXPES-Lab system was installed. The HAXPES-Lab is a home laboratory-type hard X-ray photoelectron spectroscopy (HAXPES) system with the key components: monochromator, high energy analyzer and a 9 keV X-ray source, the Excillum MetalJet D2+.
The non-destructive technique of HAXPES opens up a window to the bulk, as the technique can characterize the element-specific chemical states sub surface of materials, e.g. at buried interfaces or in the bulk. Previously, 9 keV photoemission had only been possible at synchrotron beamlines but with the introduction of the HAXPES-Lab system experiments in the home laboratory became possible, 24 hours a day, 365 days a year.
Investigation of bulk heterojunction solar cells
GISAXS and GIWAXS are X-ray methods used to give insight into the order and orientation of thin films on a substrate, typical examples include solar cells, long range order of block copolymers, nanoparticles and nanoparticle composites, membranes and lithographic patterning.
Using a high intensity X-ray source such as the MetalJet for these experiments enables in-situ investigation of materials. One example of such an in-situ study is that of Vegso at al. from the institute of physics of the Slovak academy of science. They used a laboratory GISAXS/GIWAXS setup with a MetalJet emitting Ga Kα X-ray radiation to investigate the phase separation of the polymer and the fullerene phase in a bulk heterojunction solar cell.
The size and intermixing of domains of the electron acceptor (polymer) and the electron donor (fullerene) are key determinants of the efficiency with which solar energy is converted to electrical power. The combination of GISAXS and -WAXS give unprecedented insight into the real-time structural evolution of the polymer:fullerene phase separation in terms of polymer crystallization and fullerene agglomeration. GISAXS patterns were collected with 10 second intervals and GIWAXS patterns with 2.5 second intervals. These short exposures were sufficient to follow the kinetics of the bulk heterojunction formation of the spin-coated polymer: fullerene mixture by means of tracking the ratio of assembled material versus non-assembled material (φ) as depicted in the picture to the right, the radius of gyration (Rg) of the fullerene phase and the d100 spacing of the lamellar polymer phase.
Ratio of assembled versus not assembled polymer-fullerene mixture as calculated from grazing incidence scattering measurements.
Related user story
Experiences with the Excillum X-ray sources
Learn about one of our customer's experiences with our state-of-the-art X-ray sources.
