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End date: 2023 × Start date: 2023 × End date: 2019 × DDC: 620 × Type: Text × WGL Institute: IKZ ×

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    Femtosecond laser-assisted fabrication of chalcopyrite micro-concentrator photovoltaics
    (Frankfurt, M. : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2018) Ringleb, Franziska; Andree, Stefan; Heidmann, Berit; Bonse, Jörn; Eylers, Katharina; Ernst, Owen; Boeck, Torsten; Schmid, Martina; Krüger, Jörg
    Micro-concentrator solar cells offer an attractive way to further enhance the efficiency of planar-cell technologies while saving absorber material. Here, two laser-based bottom-up processes for the fabrication of regular arrays of CuInSe2 and Cu(In,Ga)Se2 microabsorber islands are presented, namely one approach based on nucleation and one based on laser-induced forward transfer. Additionally, a procedure for processing these microabsorbers to functioning micro solar cells connected in parallel is demonstrated. The resulting cells show up to 2.9% efficiency and a significant efficiency enhancement under concentrated illumination.
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    Lithium metal penetration induced by electrodeposition through solid electrolytes: Example in single-crystal Li6La3ZrTaO12 garnet
    (Pennington, NJ : Electrochemical Society, 2018) Swamy, Tushar; Park, Richard; Sheldon, Brian W.; Rettenwander, Daniel; Porz, Lukas; Berendts, Stefan; Uecker, Reinhard; Carter, W. Craig; Chiang, Yet-Ming
    Solid electrolytes potentially enable rechargeable batteries with lithium metal anodes possessing higher energy densities than today’s lithium ion batteries. To do so the solid electrolyte must suppress instabilities that lead to poor coulombic efficiency and short circuits. In this work, lithium electrodeposition was performed on single-crystal Li6La3ZrTaO12 garnets to investigate factors governing lithium penetration through brittle electrolytes. In single crystals, grain boundaries are excluded as paths for lithium metal propagation. Vickers microindentation was used to introduce surface flaws of known size. However, operando optical microscopy revealed that lithium metal penetration propagates preferentially from a different, second class of flaws. At the perimeter of surface current collectors smaller in size than the lithium source electrode, an enhanced electrodeposition current density causes lithium filled cracks to initiate and grow to penetration, even when large Vickers defects are in proximity. Modeling the electric field distribution in the experimental cell revealed that a 5-fold enhancement in field occurs within 10 micrometers of the electrode edge and generates high local electrochemomechanical stress. This may determine the initiation sites for lithium propagation, overriding the presence of larger defects elsewhere.
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    Adsorption-controlled growth of La-doped BaSnO3 by molecular-beam epitaxy
    (Melville, NY : AIP Publ., 2017) Paik, Hanjong; Chen, Zhen; Lochocki, Edward; Seidner H., Ariel; Verma, Amit; Tanen, Nicholas; Park, Jisung; Uchida, Masaki; Shang, ShunLi; Zhou, Bi-Cheng; Brützam, Mario; Uecker, Reinhard; Liu, Zi-Kui; Jena, Debdeep; Shen, Kyle M.; Muller, David A.; Schlom, Darrell G.
    Epitaxial La-doped BaSnO3 films were grown in an adsorption-controlled regime by molecular-beam epitaxy, where the excess volatile SnOx desorbs from the film surface. A film grown on a (001) DyScO3 substrate exhibited a mobility of 183 cm2 V-1 s-1 at room temperature and 400 cm2 V-1 s-1 at 10 K despite the high concentration (1.2 × 1011 cm-2) of threading dislocations present. In comparison to other reports, we observe a much lower concentration of (BaO)2 Ruddlesden-Popper crystallographic shear faults. This suggests that in addition to threading dislocations, other defects - possibly (BaO)2 crystallographic shear defects or point defects - significantly reduce the electron mobility.