@article{PfetschFuegenschuhGeissleretal.2014, author = {Pfetsch, Marc and F{\"u}genschuh, Armin and Geißler, Bj{\"o}rn and Geißler, Nina and Gollmer, Ralf and Hiller, Benjamin and Humpola, Jesco and Koch, Thorsten and Lehmann, Thomas and Martin, Alexander and Morsi, Antonio and R{\"o}vekamp, Jessica and Schewe, Lars and Schmidt, Martin and Schultz, R{\"u}diger and Schwarz, Robert and Schweiger, Jonas and Stangl, Claudia and Steinbach, Marc and Vigerske, Stefan and Willert, Bernhard}, title = {Validation of Nominations in Gas Network Optimization: Models, Methods, and Solutions}, journal = {Optimization Methods and Software}, publisher = {Taylor \& Francis}, doi = {10.1080/10556788.2014.888426}, year = {2014}, abstract = {In this article we investigate methods to solve a fundamental task in gas transportation, namely the validation of nomination problem: Given a gas transmission network consisting of passive pipelines and active, controllable elements and given an amount of gas at every entry and exit point of the network, find operational settings for all active elements such that there exists a network state meeting all physical, technical, and legal constraints. We describe a two-stage approach to solve the resulting complex and numerically difficult feasibility problem. The first phase consists of four distinct algorithms applying linear, and methods for complementarity constraints to compute possible settings for the discrete decisions. The second phase employs a precise continuous programming model of the gas network. Using this setup, we are able to compute high quality solutions to real-world industrial instances that are significantly larger than networks that have appeared in the mathematical programming literature before.}, language = {en} } @article{LockauSontheimerPreideletal.2014, author = {Lockau, Daniel and Sontheimer, Tobias and Preidel, Veit and Ruske, Florian and Hammerschmidt, Martin and Becker, Christiane and Schmidt, Frank and Rech, Bernd}, title = {Advanced microhole arrays for light trapping in thin film silicon solar cells}, volume = {125}, journal = {Solar Energy Materials and Solar Cells}, doi = {10.1016/j.solmat.2013.11.024}, pages = {298 -- 304}, year = {2014}, language = {en} } @article{KirnerHammerschmidtSchwankeetal.2014, author = {Kirner, Simon and Hammerschmidt, Martin and Schwanke, Christoph and Lockau, Daniel and Calnan, Sonya and Frijnts, Tim and Neubert, Sebastian and Sch{\"o}pke, Andreas and Schmidt, Frank and Zollondz, Jens-Hendrik and Heidelberg, Andreas and Stannowski, Bernd and Rech, Bernd and Schlatmann, Rutger}, title = {Implications of TCO Topography on Intermediate Reflector Design for a-Si/μc-Si Tandem Solar Cells — Experiments and Rigorous Optical Simulations}, volume = {4}, journal = {IEEE Journal of Photovoltaics}, number = {1}, doi = {10.1109/JPHOTOV.2013.2279204}, pages = {10 -- 15}, year = {2014}, language = {en} } @inproceedings{HammerschmidtPomplunBurgeretal.2014, author = {Hammerschmidt, Martin and Pomplun, Jan and Burger, Sven and Schmidt, Frank}, title = {Adaptive sampling strategies for effcient parameter scans in nano-photonic device simulations}, volume = {8980}, booktitle = {Proc. SPIE}, publisher = {SPIE}, doi = {10.1117/12.2036363}, pages = {89801O}, year = {2014}, language = {en} } @inproceedings{HammerschmidtLockauZschiedrichetal.2014, author = {Hammerschmidt, Martin and Lockau, Daniel and Zschiedrich, Lin and Schmidt, Frank}, title = {Optical modelling of incoherent substrate light-trapping in silicon thin film multi-junction solar cells with finite elements and domain decomposition}, volume = {8980}, booktitle = {Proc. SPIE: Physics and Simulation of Optoelectronic Devices XXII}, publisher = {SPIE}, doi = {10.1117/12.2036346}, pages = {898007}, year = {2014}, language = {en} } @inproceedings{LockauHammerschmidtHaschkeetal.2014, author = {Lockau, Daniel and Hammerschmidt, Martin and Haschke, Jan and Blome, Mark and Ruske, Florian and Schmidt, Frank and Rech, Bernd}, title = {A comparison of scattering and non-scattering anti-reflection designs for back contacted polycrystalline thin film silicon solar cells in superstrate configuration}, volume = {9140}, booktitle = {Proc. SPIE}, doi = {10.1117/12.2052362}, pages = {914006}, year = {2014}, language = {en} } @misc{HammerschmidtPomplunBurgeretal.2014, author = {Hammerschmidt, Martin and Pomplun, Jan and Burger, Sven and Schmidt, Frank}, title = {Adaptive sampling strategies for efficient parameter scans in nano-photonic device simulations}, issn = {1438-0064}, doi = {10.1117/12.2036363}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-50395}, year = {2014}, abstract = {Rigorous optical simulations are an important tool in optimizing scattering properties of nano-photonic devices and are used, for example, in solar cell optimization. The finite element method (FEM) yields rigorous, time-harmonic, high accuracy solutions of the full 3D vectorial Maxwell's equations [1] and furthermore allows for great flexibility and accuracy in the geometrical modeling of these often complex shaped 3D nano-structures. A major drawback of frequency domain methods is the limitation of single frequency evaluations. For example the accurate computation of the short circuit current density of an amorphous silicon / micro-crystalline multi-junction thin film solar cell may require the solution of Maxwell's equations for over a hundred different wavelengths if an equidistant sampling strategy is employed. Also in optical metrology, wavelength scans are frequently used to reconstruct unknown geometrical and material properties of optical systems numerically from measured scatterometric data. In our contribution we present several adaptive numerical integration and sampling routines and study their efficiency in the context of the determination of generation rate profiles of solar cells. We show that these strategies lead to a reduction in the computational effort without loss of accuracy. We discuss the employment of tangential information in a Hermite interpolation scheme to achieve similar accuracy on coarser grids. We explore the usability of these strategies for scatterometry and solar cell simulations.}, language = {en} } @misc{HammerschmidtLockauZschiedrichetal.2014, author = {Hammerschmidt, Martin and Lockau, Daniel and Zschiedrich, Lin and Schmidt, Frank}, title = {Optical modelling of incoherent substrate light-trapping in silicon thin film multi-junction solar cells with finite elements and domain decomposition}, issn = {1438-0064}, doi = {10.1117/12.2036346}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-50410}, year = {2014}, abstract = {In many experimentally realized applications, e.g. photonic crystals, solar cells and light-emitting diodes, nano-photonic systems are coupled to a thick substrate layer, which in certain cases has to be included as a part of the optical system. The finite element method (FEM) yields rigorous, high accuracy solutions of full 3D vectorial Maxwell's equations [1] and allows for great flexibility and accuracy in the geometrical modelling. Time-harmonic FEM solvers have been combined with Fourier methods in domain decomposition algorithms to compute coherent solutions of these coupled system. [2,3] The basic idea of a domain decomposition approach lies in a decomposition of the domain into smaller subdomains, separate calculations of the solutions and coupling of these solutions on adjacent subdomains. In experiments light sources are often not perfectly monochromatic and hence a comparision to simulation results might only be justified if the simulation results, which include interference patterns in the substrate, are spectrally averaged. In this contribution we present a scattering matrix domain decomposition algorithm for Maxwell's equations based on FEM. We study its convergence and advantages in the context of optical simulations of silicon thin film multi-junction solar cells. This allows for substrate light-trapping to be included in optical simulations and leads to a more realistic estimation of light path enhancement factors in thin-film devices near the band edge.}, language = {en} } @misc{LockauHammerschmidtBlomeetal.2014, author = {Lockau, Daniel and Hammerschmidt, Martin and Blome, Mark and Schmidt, Frank}, title = {Optics of thin film solar cells}, volume = {1}, journal = {MATHEON-Mathematics for Key Technologies}, editor = {Deuflhard, Peter and et al.,}, publisher = {European Mathematical Society}, doi = {10.4171/137}, pages = {278 -- 279}, year = {2014}, language = {en} }