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
About 90% of all mechanical service failures are caused by fatigue. Avoiding fatigue failure requires addressing the wide knowledge gap regarding the micromechanical processes governing damage under cyclic loading, which may be fundamentally different from that under static loading. This is particularly true for deformation-induced martensitic…
With the support of DFG, in this project the interaction of H with mechanical, chemical and electrochemical properties in ferritic Fe-based alloys is investigated by the means of in-situ nanoindentation, which can characterize the mechanical behavior of independent features within a material upon the simultaneous charge of H.
The full potential of energy materials can only be exploited if the interplay between mechanics and chemistry at the interfaces is well known. This leads to more sustainable and efficient energy solutions.
This project aims to correlate the localised electrical properties of ceramic materials and the defects present within their microstructure. A systematic approach has been developed to create crack-free deformation in oxides through nanoindentation, while the localised defects are probed in-situ SEM to study the electronic properties. A coupling…
