Chemical fluctuations in polycrystalline thin-films for photovoltaic devices
Within this project we investigate chemical fluctuations at the nanometre scale in polycrystalline Cu(In,Ga)Se2 and CuInS2 thin-flims used as absorber material in solar cells.
Secondary phase formation as well as chemical fluctuations such as impurity segregation at structural defects like grain boundaries can significantly affect the optoelectronical properties of photovoltaic materials. Within this project we investigate such chemical fluctuations at the nanometre scale in polycrystalline Cu(In,Ga)Se2 and CuInS2 thin-flims used as absorber material in solar cells. We apply combined scanning transmission electron microscopy (STEM) with energy dispersive X-ray spectroscopy (EDX) as well as correlated transmission Kikuchi diffraction (TKD) and atom probe tomography (APT).
Accumulation and diffusion of Na (green) along Cu depleted structural defects (blue) in epitaxial grown CuInSe2 films on GaAs substrate
Mechanistic description of In/Ga interdiffusion. STEM-BF image of a cross section from a Na2Se treated CuInSe2 film grown on GaAs substrate and corresponding Ga, In and Cu elemental maps.
Mechanistic description of In/Ga interdiffusion. STEM-BF image of a cross section from a Na2Se treated CuInSe2 film grown on GaAs substrate and corresponding Ga, In and Cu elemental maps.
Image quality maps from a TKD measurement of an APT needle and corresponding unique color map showing a RHAGB (blue) and ∑3 TB (red). Na & C co-segregation as well as Cu enrichment (blue iso-concentration surface) at the RHAGB. Concentration profile across the RHAGB revealing an atomic redistribution.
Image quality maps from a TKD measurement of an APT needle and corresponding unique color map showing a RHAGB (blue) and ∑3 TB (red). Na & C co-segregation as well as Cu enrichment (blue iso-concentration surface) at the RHAGB. Concentration profile across the RHAGB revealing an atomic redistribution.
International researcher team presents a novel microstructure design strategy for lean medium-manganese steels with optimized properties in the journal Science
In this project, links are being established between local chemical variation and the mechanical response of laser-processed metallic alloys and advanced materials.
The atomic arrangements in extended planar defects in different types of Laves phases is studied by high-resolution scanning transmission electron microscopy. To understand the role of such defect phases for hydrogen storage, their interaction with hydrogen will be investigated.
The mechanical properties of bulk CrFeCoNi compositionally complex alloys (CCA) or high entropy alloys (HEA) are widely studied in literature [1]. Notably, these alloys show mechanical properties similar to the well studied quinary CrMnFeCoNi [2] . Nevertheless, little is known about the deformation mechanisms and the thermal behavior of these…
Efficient harvesting of sunlight and (photo-)electrochemical conversion into solar fuels is an emerging energy technology with enormous promise. Such emerging technologies depend critically on materials systems, in which the integration of dissimilar components and the internal interfaces that arise between them determine the functionality.