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- Edoff, Marika, 1965-, et al.
(författare)
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Ultrathin CIGS Solar Cells with Passivated and Highly Reflective Back Contacts – : Results from the ARCIGS-M Consortium
- 2019
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Ingår i: Proceedings of 36th European Photovoltaic Solar Energy Conference and Exhibition. ; , s. 597-600
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this work, we report results from the EU-funded project ARCIGS-M. The project started in 2016 and aims to reduce the use of indium and gallium by enabling the use of very thin Cu(In,Ga)Se2 (CIGS) layers while retaining high efficiency and developing innovative low-cost steel substrates as alternatives to glass. In the project, reflective layers containing TCO´s and silver have successfully been used to enhance the reflective properties of the rear contact. In addition, passivation layers based on alumina (Al2O3) deposited by atomic layer deposition (ALD) have been found to yield good passivation of the rear contact. Since the alumina layers are dielectric, perforation of these layers is necessary to provide adequate contacting. The design of the perforation patterns has been investigated by a combination of modeling and experimental verification by electron beam lithography. In parallel a nano-imprint lithography (NIL) process is further developed for scale-up and application in prototype modules. Advanced optoelectrical characterization supported by modeling is used to fill in the missing gaps in optical and electrical properties, regarding CIGS, interfaces and back contact materials.
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| 2. |
- Gusak, Viktoria, 1983, et al.
(författare)
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Diffusion and adsorption of dye molecules in mesoporous TiO2 photoelectrodes studied by indirect nanoplasmonic sensing
- 2013
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Ingår i: Energy and Environmental Sciences. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 6:12, s. 3627-3636
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we used Hidden Interface-Indirect Nanoplasmonic Sensing (HI-INPS) for real time monitoring of dye impregnation (adsorption-diffusion process) of mesoporous TiO2 electrodes of the kind used in dye-sensitized solar cells. We measured the dye percolation time (i.e. the time to diffuse to the bottom of a TiO2 photoelectrode film) for dye Z907 in a 1 : 1 volume mixture of acetonitrile and tert-butanol for different dye concentrations and for different thicknesses of the TiO2 film, while the total amount of adsorbed dye was simultaneously measured by optical absorption spectroscopy. The experimental data for the impregnation process were analyzed by employing a diffusion-front model, combining diffusion and Langmuir type adsorption, which allows extraction of the effective diffusion coefficient for the system. The latter value is about 15 mu m(2) s(-1) for the combined adsorption-diffusion movement of dye molecules through the TiO2 structure, which is an order of magnitude or more smaller than that for "free" diffusion of dye molecules in bulk solvents.
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| 7. |
- Gusak, Viktoria, 1983
(författare)
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Nanoparticle plasmonics for solar cell applications
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The energy demand of society increases rapidly, while the main source of today’s energy, the fossil fuels, eventually will be depleted and also poses environmental and climate hazards (though the global warming). Therefore there is a need for alternative, renewable energy sources, and solar photovoltaics (solar cells) will play an important role as one of them. The photovoltaics research is very extensive today, but the relatively high cost of solar cells and their intermittent production of electricity make solar cells still loose in the energy market competition. Efficiency is also an issue.This thesis explores novel concepts, enabled by advances in nanotechnology, in the solar cell research. In particular, it focuses on applying the phenomenon called plasmon resonance in metal nanoparticles, to study and improve thin-film solar cells. The plasmon resonance is a collective oscillation of conduction electrons in a metal nanostructure, which can be excited by light. This phenomenon leads to interesting ways through which the nanoparticle interacts with light and with its own nanorange environment; in particular, the electric field in the close vicinity of the particle is largely enhanced compared to the incident light. This thesis focuses on employing this enhanced field to (i) enhance light absorption in thin amorphous Silicon (a-Si) films and (ii) sense adsorption and diffusion of dye molecules in titania (TiO2) films, used for dye sensitized solar cells (DSC).In the first part of the thesis, photoconductivity measurements were performed on a-Si films, with and without plasmonic Ag nanoparticles, in order to quantify the ‘extra’ light absorption in a-Si films caused by the enhanced near-field around the nanoparticles. The plasmon induced light absorption was studied as a function of a-Si film thickness, and was found to be maximal (15% absolute increase of absorptance, from 22% to 37%) in a 9 nm thick a-Si film. The finite-element method calculations reproduced the experimental results reasonably well. The observed plasmon-induced increase in the light absorption is substantial and it has a large potential toward realizing an ultrathin (about 20 nm) a-Si solar cell with efficiency similar to that of the standard (about 300 nm thick) a-Si cell.In the second part of the thesis, Indirect Nanoplasmonic Sensing was used to study adsorption kinetics of dye molecules on TiO2 films. The concept was first demonstrated on thin (12-70 nm) compact TiO2 films that serve as a model system, and was extended toward thick (10 µm) mesoporous TiO2 film of the kind used in dye solar cells. The short-range sensitivity of the plasmonic nanoparticles allows monitoring processes locally in their vicinity, i.e. at the interface between the TiO2 film and the support, mimicking the electron collecting electrode. This technique has a large potential for studying combined diffusion and adsorption kinetics for DSCs, as well as for similar phenomena in a broad range of other (meso-)porous materials.
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| 8. |
- Gusak, Viktoria, 1983
(författare)
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Nanoplasmonics for solar cells
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main source of our energy system, the fossil fuels, will eventually be depleted and also pose environmental and climate hazards. There is thus a need for alternative, renewable energy sources. Solar (photovoltaic) cells will play an important role as one of them. The photovoltaics research is extensive today, but the relatively high cost of solar cells and/or insufficient efficiency make them still often loose in the energy market competition.This thesis explores novel concepts for solar cell research, enabled by advances in nanotechnology, specifically applying the phenomenon called plasmon resonance in metal nanoparticles, to study and improve thin-film solar cells. The plasmon resonance is a collective oscillation of conduction electrons in a metal nanostructure, which can be excited by light. It leads to interesting and potentially useful interactions between nanoparticles and light; in particular, the electric field in the vicinity of the nanoparticle is enhanced compared to that of the incident light. This work focuses on employing the enhanced field to (i) improve light absorption in thin amorphous silicon (a-Si:H) films and (ii) to sense adsorption and diffusion of dye molecules in TiO2 films, used for dye-sensitized solar cells.In the first part of the thesis, optical and photoconductivity measurements were performed on ultrathin a-Si:H films, with and without Ag plasmonic nanoparticles, in order to quantify the light absorption in a-Si:H films caused by the enhanced near-field around the nanoparticles. The effect was studied for (i) systems of Ag nanodiscs coated with a-Si:H films of various thicknesses, and (ii) Ag cone/a-Si:H nanocomposites placed on a reflector-spacer structure with varied geometric parameters. Finite-element method calculations were used to connect observed experimental features to specific plasmon resonance modes, and to explain mechanisms of absorption enhancement in the a-Si:H films.The second part of the thesis is focused on adsorption and diffusion kinetics of dye molecules on TiO2 films, studied by Indirect NanoPlasmonic Sensing (INPS) and Quartz crystal microbalance with dissipation monitoring (QCM-D) techniques. Measurements on flat film model systems revealed details of adsorption and desorption kinetics and allowed extracting the corresponding rate constants. Incorporating plasmonic sensing nanoparticles within mesoporous TiO2 films provides a unique opportunity to resolve adsorption kinetics locally in the film (in this case, at the bottom of the mesoporous TiO2 films). Diffusion times for dye molecules through the mesoporous films were measured and modelled with a diffusion-front model. This allowed deriving the effective diffusion coefficient of the dye molecules in this system.
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| 9. |
- Gusak, Viktoria, 1983, et al.
(författare)
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Real time adsorption and desorption kinetics of dye Z907 on a flat mimic of dye-sensitized solar cell TiO2 photoelectrodes
- 2014
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:30, s. 17116-17122
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Tidskriftsartikel (refereegranskat)abstract
- A dye molecule monolayer formed on a TiO2 surface is a key component in dye-sensitized solar cells. It is usually formed by adsorbing dye molecules from a solution. The dye layer should absorb as much solar light as possible and convert the light to photoelectrons, which are injected into the TiO2 conduction band. For that purpose the dye molecules should adsorb on TiO2 with appropriate molecular orientation and close packing. We measured adsorption and desorption kinetics of dye Z907 on thin compact TiO2 films in real time using indirect nanoplasmonic sensing. From kinetic curves, we derived adsorption and desorption rate constants in a direct way, which has not been done for such systems previously. We then derived the equilibrium adsorption constant from both kinetics (by the ratio of the adsorption and desorption rate constants) and from a measured Langmuir isotherm obtained experimentally using the same method, the same sample, and the same experiment. The two values are in reasonably good agreement considering possible error sources; our approach thus constitutes an effective method of determining more reliable equilibrium constants for dye-TiO2 systems. Furthermore, by measuring a series of intermittent adsorption-desorption steps, we found successively less desorption at a given coverage after each rinsing step and conclude that there are different binding states and that reorganization of the dye molecules on the TiO2 surface occurs over rather long time scales. The rearrangement process seems to accelerate by intermittent rinsing and associated desorption of loosely bound molecules. The results suggest that the detailed conditions for the dye impregnation kinetics can be used to optimize the dye layer.
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