Forschungszentrum Juulich GmbH

Cluster, Germany

Forschungszentrum Juulich GmbH

Cluster, Germany
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Kim D.Y.,Technical University of Delft | Kim D.Y.,Forschungszentrum Juulich GmbH | Guijt E.,Technical University of Delft | Van Swaaij R.A.C.M.M.,Technical University of Delft | Zeman M.,Technical University of Delft
Journal of Applied Physics | Year: 2017

Hydrogenated amorphous silicon oxide (a-SiOx:H) solar cells have been successfully implemented to multi-junction thin film silicon solar cells. The efficiency of these solar cells, however, has still been below that of state-of-the-art solar cells mainly due to the low Jsc of the a-SiOx:H solar cells and the unbalanced current matching between sub-cells. In this study, we carry out optical simulations to find the main optical losses for the a-SiOx:H solar cell, which so far was mainly optimized for Voc and fill-factor (FF). It is observed that a large portion of the incident light is absorbed parasitically by the p-a-SiOx:H and n-a-SiOx:H layers, although the use of these layers leads to the highest Voc × FF product. When a more transparent and conductive p-nc-SiOx:H layer is substituted for the p-a-SiOx:H layer, the parasitic absorption loss at short wavelengths is notably reduced, leading to higher Jsc. However, this gain in Jsc by the use of the p-nc-SiOx:H compromises the Voc. When replacing the n-a-SiOx:H layer for an n-nc-SiOx:H layer that has low n and k values, the plasmonic absorption loss at the n-nc-SiOx:H/Ag interfaces and the parasitic absorption in the n-nc-SiOx:H are substantially reduced. Implementation of this n-nc-SiOx:H leads to an increase of the Jsc without a drop of the Voc and FF. When implementing a thinner p-a-SiOx:H layer, a thicker i-a-SiOx:H layer, and an n-nc-SiOx:H layer, a-SiOx:H solar cells with not only high Jsc but also high Voc and FF can be fabricated. As a result, an 8.8% a-SiOx:H single junction solar cell is successfully fabricated with a Voc of 1.02 V, a FF of 0.70, and a Jsc of 12.3 mA/cm2, which is the highest efficiency ever reported for this type of solar cell. © 2017 Author(s).


Rimini F.G.,Culham Center for Fusion Energy | Alves D.,University of Lisbon | Arnoux G.,Culham Center for Fusion Energy | Baruzzo M.,Consorzio RFX | And 12 more authors.
Fusion Engineering and Design | Year: 2015

The JET tokamak is unique amongst present fusion devices in its capability to operate at high plasma current, providing the closest plasma parameters to ITER. The physics benefits of high current operation have to be balanced against the risks to the integrity of the machine due to high force disruptions. The installation of the ITER-Like Wall (ILW) has added risks due to the thermal characteristics of the metal Plasma Facing Components. This paper describes the operational aspects of the scientific development of high current H-mode plasmas with the ILW, focusing on disruption prediction, avoidance and amelioration. The development yielded baseline H-mode plasmas up to 4 MA/3.74 T, comparable to the maximum current achieved in JET in Carbon-Wall (CFC) conditions with similar divertor geometry. © 2015 EURATOM. Published by Elsevier B.V. All rights reserved.


Weidenbach D.,RWTH Aachen | Jansen M.,Forschungszentrum Juulich GmbH | Jansen M.,LemnaTec | Bodewein T.,Forschungszentrum Juulich GmbH | And 2 more authors.
Plant Signaling and Behavior | Year: 2015

Aerial parts of plants are separated from the environment by a cuticle which functions in protection against desiccation and pathogen attack. Recently, we reported on a barley mutant with defect in the 3-KETOACYL-CoASYNTHASE (HvKCS6) gene, resulting in reduced coverage of the cuticle with epicuticular waxes. Spores of adapted and non-adapted powdery mildew fungi germinated less frequently on mutant leaves possibly because plant derived signals are missing. We used a shoot and root phenotyping facility to test whether depletion in epicuticular waxes negatively impacts plant performance under waterlimiting conditions. While shoots of mutant plants grew slower at wellwatered conditions than wild-type plants, they showed an equal or slightly better growth rate at water limitation. Also for roots, differences between mutant and parental line were less prominent at water-limiting as compared to wellwatered conditions. Our results challenge the intuitive belief that reduced epicuticular wax might become a drawback at water limitation. © 2015 Taylor & Francis Group, LLC.

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