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27th European Photovoltaic Solar Energy Conference and Exhibition; 1864-1866, In order to improve the efficiency of multi-crystalline silicon (mc-Si) solar cells, ablation by laser radiation has been adopted as a non-contact tool for various processes. With ultra-short pulsed laser radiation the reflectivity of silicon is decreased by altering the surface topology and increases the efficiency of the solar cells. The formation of structures in the μm-range on the surface of silicon is investigated with respect to the focal diameters at constant laser parameters. The most promising laser parameters reducing the reflectivity of the solar cells are identified. Multicrystalline silicon solar wafers with an edge length of 5 inch and a laser generated μm-scale surface structures, so called “Black Silicon”, were finally processed into cells. The achieved absolute efficiency gain has been measured to = 0.21 %.

27th European Photovoltaic Solar Energy Conference and Exhibition; 2914-2918, Laser scribing is a suitable structuring method for thin-film organic solar modules on PET-foil aiming the roll-to-roll processing. Results on laser scribing of a transparent electrode: highly conductive PEDOT:PSS, as an alternative to the conventionally used ITO are presented. The most important parameters in thin film laser processing are the wavelength, pulse duration, pulse energy, and spot-to-spot overlap. Effects and dependencies on material ablation by processing with laser radiation at several wavelengths (e.g. 355 nm, 532 nm, and 1064 nm) and pulse durations in the pico-, subnano-, and nanosecond range were studied. Organic test modules were produced using laser structuring. Optimal processing parameters and laser sources are discussed considering a feasible and rapid implementation into a roll-to-roll mass production system.

26th European Photovoltaic Solar Energy Conference and Exhibition; 1735-1738, In order to improve the efficiency of multi-crystalline (mc)-silicon solar cells, laser ablation as a noncontact tool is highly suitable for various processes. Apart from the laser and scanning parameters frequently reported in the literature, other factors exist upon which the observable results of laser edge isolation depend. In addition to laser and scanning parameters, the influence of various atmospheres on the laser edge isolation process is investigated in this work. The impact on the dopant concentration in the generated laser groove is investigated with reference to the shunt resistance of the solar cells. Furthermore remaining oxygen concentrations are measured in the ablation groove by EDX. These results yield an improved understanding of the impact of oxygen concentration in the ambient air during laser edge isolation. From these investigations the most suitable laser is determined as well as ambient parameters for the ablation of mc-silicon.

26th European Photovoltaic Solar Energy Conference and Exhibition; 2641-2644, Roll-to-roll production of thin-film photovoltaic (PV) solar cells and modules is expected to substantially decrease the manufacturing costs, and thus enable a breakthrough in the price of solar electricity per kWh. Generic processes such as depth-selective laser scribing and the printing of insulating and conductive tracks curable at low temperature are a key requirement to enable cost efficient production of advanced thin-film PV concepts. In contrast to TCO glass based superstrate device concepts, no standard laser scribing processes and manufacturing tools to achieve fully monolithic series interconnection are presently available for so-called substrate type device concepts that are built on – often opaque and even flexible – substrates. Three key features of such advanced interconnection processes are presented here: laser scribing, printing and electrical modeling. We show that laser scribing of amorphous silicon solar cells with a 1064 nm ps laser leads to a minor loss in efficiency. The screen printing process of low-temperature curing Ag paste is also proven not to degrade the device performance, and by modelling the module interconnection, we calculated losses below 10% when going from individual cells to modules. Finally, efforts are underway to realize large area solar cells with printed current collecting grids, and a fully series interconnected module by combining laser scribing and printing as cost-effective processing operation.

25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 319-324, This paper describes the monolithic series connection of organic thin-film solar modules by means of laser structuring. Experiments are performed with a broad range of laser sources and parameters. The most important laser parameters in thin film processing are the radiation wavelength, pulse duration, pulse energy and spot-to-spot overlap. Processing with several wavelengths (e.g. 355 nm, 532 nm, and 1064 nm) and pulse durations in the femto-, pico- and nanosecond ranges are evaluated. The results obtained with the best suitable laser sources are further optimized and presented in this paper. The focus of the experiments is to obtain an optimal edge quality without damaging the substrate or the layer below the structured region. Organic test cells on glass substrates are produced using the optimized laser structuring process. These are analysed and have an efficiency comparable to cells structured with methods, commonly used in research laboratories. The presented results, show the applicability of the technology for future mass production where processing speeds greater than 1m/s are required. Currently available industrial laser sources are able to achieve these processing speeds, necessary for economically feasible structuring of organic modules in a roll-to-roll production.

25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 1984-1990, The laser is an extremely suitable non-contact tool for automated processes needed in order to improve the efficiency of solar cells. One of the most common laser processes in the production of crystalline silicon solar cells is laser edge isolation. Ultra–short pulse laser sources with sufficient power to meet 1 s cycle time promise to improve the process. Due to the short interaction time they ablate material nearly without melting and hence reduce losses in the cells due to thermal damage which would occur during ablation caused by nanosecond laser pulses. The necessary ablation depths for successful pn-junction isolation can achieved either by using high pulse energy at a certain repetition rate or by using much higher repetition rates with a lower pulse energy such that more pulses are released per area in the same period of time. These two approaches lead to different thermal impacts, morphology and shunt resistances. Furthermore, it is shown that the complete ablation of the n+-doped layer, with a thickness of approx. 0.5 μm, is not sufficient for edge isolation even if an ultra-short pulse laser is used. This is visualized by a logistic model used to describe shunt resistance as a function of depth.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 1771-1774, The choice of laser parameters for a laser doping process [1, 2] is investigated. Solid state lasers with different pulse- and wavelengths were used for laser doping. Sheet resistances and silicon bulk lifetimes of irradiated samples are presented. Additionally, secondary ion mass spectroscopy (SIMS) profiles of the laser processed samples were acquired. Emitter saturation current density J0e data of lowly doped and laser doped emitters are shown. Scanning electron microscope images of laser processed random pyramids surfaces at different pulse lengths are shown and compared.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 1803-1806, Picosecond laser sources can ablate Si nearly without melting and hence are a promising alternative for pn-junction isolation. In this work the shunt resistance and microstructure obtained by a new high-power picosecond laser source are compared with that of a standard nanosecond laser. As a result, the picosecond laser creates a threefold higher median shunt resistance at a high number of passes. The observed microstructure is a strong function of the laser fluence. In the thermal regime, i. e. at laser fluences above 1.1 J/cm², the n+-diffused layer directly evaporates and the newly created surface is relatively smooth. In the non-thermal regime at laser fluences below 1.1 J/cm² a very rough microstructure arises and porous SiOx is formed. It is assumed that the SiOx decreases the conductivity of the topmost Si layer in the laser groove. In both regimes high shunt resistances can be obtained as confirmed by infrared imaging under reverse bias. In contrast, for cells edge-isolated by means of the nanosecond-laser parasitic shunting is observed.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 1204-1208, Local contact openings in dielectric passivating layers of solar cells reduce recombination losses and offer an attractive alternative to “fire-through” processes such as screen printing of grid lines on the front side. Laser ablation with ultra short pulses is particularly suitable for contactless industrial processing of high-efficiency silicon solar cells. In the present paper, we investigate picosecond laser ablation of passivating SiO2 and SiNx layers on planar and textured silicon surfaces for various wavelengths of laser radiation. We characterise ps-laser ablated contact openings on 40 - 100 Ω/sq emitters by lifetime and contact resistance measurements. Our results show that for infrared and for visible wavelengths the local emitter saturation current densities in laser treated areas are 1 to 4 pA/cm² when ablating SiNx and SiO2 layers from planar surfaces. However, ps-laser ablation on alkaline textured surfaces results in server crystal damage. Specific contact resistance values of < 1 mΩcm² are achieved. We characterise the total recombination current densities by measurements of the J-V characteristics of laser treated diodes. Assuming 3% metallised area the efficiency loss compared to wet chemically treated solar cells is very low and amounts to 0.2% absolute.

A high resolution machining setup for creating three-dimensional precision components from a UV-curable photo-resin has been developed. By using frequency-converted diode-pumped solid state lasers, functional micro-mechanical devices are directly fabricated in a successive layer-bylayer fashion. Within this paper, the direct generation of micro assemblies having moving components without further assembly of parts will be presented. The micro system design is based on user-defined 3D-CAD data and will completively be built up within the fabrication cycle. By using specially developed μSL materials with suitable properties for micromechanical parts, the development from Rapid Prototyping towards Rapid Production of small series is intended.

Die Fertigung von Präzisionsthermometern und Aärometern erfolgt heutzutage im Großteil in Handarbeit durch erfahrene Fachkräfte. Dieser Beitrag zeigt die Überführung der Fertigungsprozesse in eine automatisierte Fertigung. Insbesondere wird das neuartige Maschinenkonzept vorgestellt und die Möglichkeiten der Rohrglasbearbeitung mittels Laser im Bereich Formen und Fügen aufgezeigt., 2085

During summer 1987, the R/V Polarstern of the Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Federal Republic of Germany (FRG), succeeded in penetrating the eastern Arctic ice pack as far north as the Nansen-Gakkel Ridge in the central eastern Arctic Basin. Our northernmost location, at 86°H′N (Figure 1), was further north than any surface vessel dedicated to marine research has attained previously, although Soviet nuclear-powered ice breakers have managed to penetrate to the North Pole. Prior to this cruise, most knowledge about the eastern Arctic Basin came from remote sensing techniques, Nansen's Fram expedition during 1893–1896 [Boggild, 1906; Gran, 1904; Nansen, 1902, 1904, 1906], Russian ice camps [Gordienko and Laktionov, 1969], the U.S. ice island camps Fram I-Fram IV, 1979–1982 [Hunkins et al, 1979; Baggeroer and Dyer, 1982; Manley et al, 1982; Kristoffersen, 1982; Kristoffersen et al, 1982; Kristoffersen and Husebye, 1985], and explorations by submarines.

Berichte - Reports, Geologisch-Pal��ontologisches Institut und Museum, Christian-Albrechts-Universit��t, Kiel