1,721,049 research outputs found
Multifunktionale Aluminiumoberflächen durch laserinduzierte Verfahren
No full textLaserlicht bietet, durch seine hohe gebündelte, Energie eine Vielzahl von Einsatzmöglichkeiten. Durch verschiedenste Laserverfahren können filigrane Mikrostrukturen hergestellt, mit denen sich die Benetzung und Vereisung von Aluminiumoberflächen beeinflussen lässt.Fil: Milles, Stephan. Technische Universität Dresden; AlemaniaFil: Soldera, Marcos Maximiliano. Technische Universität Dresden; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Voisiat, Bogdan. Technische Universität Dresden; AlemaniaFil: Nitschke, M.. Leibniz-institut Für Polymerforschung Dresden; AlemaniaFil: Baumann, Robert. Technische Universität Dresden; AlemaniaFil: Lasagni, Andrés Fabián. Technische Universität Dresden; Alemania. Fraunhofer Institute For Material And Beam Technology; Alemani
Optoelectronic performance of indium tin oxide thin films structured by sub-picosecond direct laser interference patterning
Full text linkA route to increase the efficiency of thin film solar cells is improving the light-trapping capacity by texturing the top Transparent Conductive Oxide (TCO) so that the sunlight reaching the solar absorber scatters into multiple directions. In this study, Indium Tin Oxide (ITO) thin films are treated by infrared sub-picosecond Direct Laser Interference Patterning (DLIP) to modify the surface topography. Surface analysis by scanning electron microscopy and confocal microscopy reveals the presence of periodic microchannels with a spatial period of 5 µm and an average height between 15 and 450 nm decorated with Laser-Induced Periodic Surface Structures (LIPSS) in the direction parallel to the microchannels. A relative increase in the average total and diffuse optical transmittances up to 10.7% and 1900%, respectively, was obtained in the 400–1000 nm spectral range as an outcome of the interaction of white light with the generated micro- and nanostructures. The estimation of Haacke’s figure of merit suggests that the surface modification of ITO with fluence levels near the ablation threshold might enhance the performance of solar cells that employ ITO as a front electrode.Fil: Heffner, Herman. Institut Für Fertigungstechnik, Technische Universität Dresden; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Soldera, Marcos Maximiliano. Technische Universität Dresden; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lasagni, Andrés Fabián. Technische Universität Dresden; Alemani
Optical Enhancement of Fluorine-Doped Tin Oxide Thin Films using Infrared Picosecond Direct Laser Interference Patterning
Full text linkSurface texturization of Transparent Conductive Oxides (TCOs) is a well-known strategy to enhance the light-trapping capabilities of thin-film solar cells and thus, to increase their power conversion efficiency. Herein, the surface modification of fluorine-doped tin oxide (FTO) using picosecond infrared direct laser interference patterning (DLIP) is presented. The surface characterization exhibits periodic microchannels, which act as diffraction gratings yielding an increase in the average diffuse transmittance up to 870% in the spectral range of 400–1000 nm. Despite the one dimensionality of the microstructures, the films did not acquire a significant anisotropic electrical behavior, but a partial deterioration of their conductivity is observed as a result of the removal of conductive material. This work proposes the feasibility of trading off a portion of the electrical conductivity to obtain a substantial improvement in the optical performance.Fil: Heffner, Herman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina. Technische Universität Dresden; AlemaniaFil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Grupo Vinculado Instituto de Ingeniería Química | Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Grupo Vinculado Instituto de Ingeniería Química; Argentina. Technische Universität Dresden; AlemaniaFil: Lasagni, Andrés Fabián. Fraunhofer–Institut für Werkstoff und Strahltechnik; Alemania. Technische Universität Dresden; Alemani
Simulations of photocurrent improvement through combined geometric/diffracting light trapping in organic small molecule solar cells
Full text linkAlthough organic solar cells have recently shown remarkable high power conversion efficiencies approaching 12%, further improvements are needed to become a low cost alternative to current inorganic photovoltaic technologies. Optical losses due to insufficient light trapping, parasitic absorption in the contact layers and reflectance limit drastically the photocurrent delivered by these solar cells. In this work, we simulated two- (2D) and three-dimensional (3D) surface textures in the micro- and submicroscale to improve light trapping in optimized organic solar cells based on copper phtalocyanine (CuPc) and fullerene (C60). The analysis was carried out with the aid of the finite elementmethod in 2Dand 3D, taking into account interference as well as reflection and diffraction of the incidentAM1.5 spectrum. At normal incidence, up to 23% improvement in the photocurrent over the planar cell was obtained. To investigate the texture performance under practical circumstances, we simulated 2D microstructures during a typical summer day, taking the change of incidence angle and radiation intensity into account. Results clearly showthat all textured cells delivermore photocurrent than the planar cell, even at oblique angles.Fil: Soldera, Marcos Maximiliano. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Electrotécnica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Estrada, Emiliano. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Electrotécnica; ArgentinaFil: Taretto, Kurt Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Electrotécnica; Argentin
Accurate explicit equations for the fill factor of real solar cells:Applications to thin-film solar cells
Full text linkEven within the simplest real solar cell model, the exact value of the fill factor (FF) is only computable by numerical calculations. Here, we perform approximations to the power-voltage curve given by the one-diode model with series and shunt resistance losses, obtaining explicit expressions for the voltage and current at the maximum power point, and thus an explicit approach for the FF. Over a broad range of possible solar cell parameters, including cells where the impact of shunt losses on the fill factor is not negligible, the approximate equations yield relative errors typically around 1%. The equations are applied to explore the dependence of FF on alternative buffer material thickness of organic solar cells, and to investigate the incidence of shunt and series resistance losses on the FF of Cu (In,Ga) Se2 solar cells under indoor illumination conditions. Fil: Taretto, Kurt Rodolfo. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Electrotecnica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte; ArgentinaFil: Soldera, Marcos Maximiliano. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Electrotecnica; ArgentinaFil: Troviano, Mauricio Eduardo. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Electrotecnica; Argentin
Structuring and functionalization of non-metallic materials using direct laser interference patterning: A review
Full text linkDirect laser interference patterning (DLIP) is a laser-based surface structuring method that stands out for its high throughput, flexibility and resolution for laboratory and industrial manufacturing. This top-down technique relies on the formation of an interference pattern by overlapping multiple laser beams onto the sample surface and thus producing a periodic texture by melting and/or ablating the material. Driven by the large industrial sectors, DLIP has been extensively used in the last decades to functionalize metallic surfaces, such as steel, aluminium, copper or nickel. Even so, DLIP processing of non-metallic materials has been gaining popularity in promising fields such as photonics, optoelectronics, nanotechnology and biomedicine. This review aims to comprehensively collect the main findings of DLIP structuring of polymers, ceramics, composites, semiconductors and other non-metals and outline their most relevant results. This contribution also presents the mechanisms by which laser radiation interacts with non-metallic materials in the DLIP process and summarizes the developed surface functions and their applications in different fields.Fil: Mulko, Lucinda. Technische Universität Dresden; AlemaniaFil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Lasagni, Andrés Fabián. Technische Universität Dresden; Alemani
Wettability control of polymeric microstructures replicated from laser-patterned stamps
Full text linkIn this study, two-step approaches to fabricate periodic microstructures on polyethylene terephthalate (PET) and poly(methyl methacrylate) (PMMA) substrates are presented to control the wettability of polymeric surfaces. Micropillar arrays with periods between 1.6 and 4.6 µm are patterned by plate-to-plate hot embossing using chromium stamps structured by four-beam Direct Laser Interference Patterning (DLIP). By varying the laser parameters, the shape, spatial period, and structure height of the laser-induced topography on Cr stamps are controlled. After that, the wettability properties, namely the static, advancing/receding contact angles (CAs), and contact angle hysteresis were characterized on the patterned PET and PMMA surfaces. The results indicate that the micropillar arrays induced a hydrophobic state in both polymers with CAs up to 140° in the case of PET, without modifying the surface chemistry. However, the structured surfaces show high adhesion to water, as the droplets stick to the surfaces and do not roll down even upon turning the substrates upside down. To investigate the wetting state on the structured polymers, theoretical CAs predicted by Wenzel and Cassie-Baxter models for selected structured samples with different topographical characteristics are also calculated and compared with the experimental data.Fil: Fu, Yangxi. Technische Universität Dresden; AlemaniaFil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentina. Technische Universität Dresden; AlemaniaFil: Wang, Wei. Technische Universität Dresden; AlemaniaFil: Milles, Stephan. Technische Universität Dresden; AlemaniaFil: Deng, Kangfa. Leibniz Institute for Solid State and Materials Research Dresden. Institute for Metallic Materials; AlemaniaFil: Voisiat, Bogdan. Technische Universität Dresden; AlemaniaFil: Nielsch, Kornelius. Leibniz Institute for Solid State and Materials Research Dresden. Institute for Metallic Materials; Alemania. Technische Universität Dresden; AlemaniaFil: Lasagni, Andrés Fabián. Technische Universität Dresden; Alemania. Fraunhofer Institute for Material and Beam Technology; Alemani
Fabrication of superhydrophobic and ice-repellent surfaces on pure aluminium using single and multiscaled periodic textures
Full text linkFabricating aluminium surfaces with superhydrophobic and ice-repellent properties present nowadays a challenging task. In this work, multifunctional structures are manufactured by direct laser writing and direct laser interference patterning methods using pulsed infrared laser radiation (1064nm). Diferent periodic patterns with feature sizes ranging from 7.0 to 50.0µm are produced. In addition, hierarchical textures are produced combining both mentioned laser based methods. Water contact angle tests at room temperature showed that all produced patterns reached the superhydrophobic state after 13 to 16 days. In addition, these experiments were repeated at substrate temperatures from −30°C to 80°C allowing to determine three wettability behaviours as a function of the temperature. The patterned surfaces also showed ice-repellent properties characterized by a near three-fold increase in the droplets freezing times compared to the untreated samples. Using fnite element simulations, it was found that the main reason behind the ice-prevention is the change in the droplet geometrical shape due to the hydrophobic nature of the treated surfaces. Finally, dynamic tests of droplets imping the treated aluminium surfaces cooled down to −20°C revealed that only on the hierarchically patterned surface, the droplets were able to bounce of the substrate.Fil: Milles, Stephan. Technische Universität Dresden; AlemaniaFil: Soldera, Marcos Maximiliano. Technische Universität Dresden; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Voisiat, Bogdan. Technische Universität Dresden; AlemaniaFil: Lasagni, Andrés Fabián. Technische Universität Dresden; Alemania. Fraunhofer Institute For Material And Beam Technology; Alemani
Characterization of self-cleaning properties on superhydrophobic aluminum surfaces fabricated by direct laser writing and direct laser interference patterning
No full textSelf-cleaning ability on technical surfaces can increase the added value of a product. A common path to achieve this property is making the surface superhydrophobic so that water droplets can roll down, picking up dirt particles. In this contribution, the self-cleaning efficiency of Al surfaces structured with direct laser writing (DLW), direct laser interference patterning (DLIP) and a combination of both technologies was quantitatively determined. This was performed by developing a characterization method, where the treated samples are firstly covered with either MnO2 or polyamide micro-particles, then tilted by 15° and 30° and finally washed applying up to nine water droplets (10 µl) over the contaminated surfaces. Then, an optical analysis by image processing of the remaining contamination particles on the textured surfaces was realized after each droplet rolled over the surface. The DLIP textures showed the best performance, allowing the removal of more than 90% of the particles after just three droplets were released. High-speed videos and scanning electron microscopy characterization allowed a deeper understanding on the cleaning behavior and on the relationship between surface microstructure and particle size and shape.Fil: Milles, Stephan. Technische Universität Dresden; AlemaniaFil: Soldera, Marcos Maximiliano. Technische Universität Dresden; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Kuntze, Thomas. Fraunhofer Institute For Material And Beam Technology; AlemaniaFil: Lasagni, Andrés Fabián. Fraunhofer Institute For Material And Beam Technology; Alemania. Technische Universität Dresden; Alemani
Combining Thickness Reduction and Light Trapping for Potential Efficiency Improvements in Perovskite Solar Cells
Full text linkIn this contribution it is shown that the efficiency of perovskite solar cells based on CH3NH3PbI3 can be increased further by combining thickness reduction of the perovskite layer and light trapping. A physical model for the current/voltage curve of pin solar cells is used to reveal the beneficial impact of thinning on cell efficiency. If interface recombination is kept at moderate levels, the model shows that there is a potential efficiency increase above 20% relative (+3% absolute) when thickness is reduced from 500 to 200 nm, provided total light absorption is maintained. A rigorous optical model is employed to calculate light absorption on typical state–of–the–art layer stacks patterned with sinusoidal grooves on ITO coated glass. The results suggest that solar light absorption in a flat, 500 nm thick film, can be matched by a 200 nm thick perovskite layer on a sinusoidal texture, while using 300 nm leads to several sinusoidal parameter combinations delivering the same light absorption. Since the structuring step must be compatible with low cost processing, it is shown that direct laser interference patterning (DLIP) is capable of delivering +3% absolute efficiency increase, while offering a typical photovoltaic module cost reduction of 10%.Fil: Soldera, Marcos Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Taretto, Kurt Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentin
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