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Scratch and mar resistance of plastic articles is a main attribute in Nordic industry with products in the premium category. Technology for improving the properties with particulate nano additives in polymers will create product benefits for either base materials or coatings. Costs and weight reductions with maintained or improved properties are prime targets but environment aspects are also focused. An effective way for improvements is offered by nanosized particles but knowledge is limited and applied research is needed.

Nanostructuring on the surface of silicon can make high efficient solar cells possible by lowering the reflection. Silicon wafers were successfully wet chemically etched with metal-assistance, to create a black silicon structure (BSiS). Different passivation layers and methods, PECVD and chemical, were tested with the purpose of decrease surface recombination. Silicon oxide was applied with PECVD with four different deposition times; 15, 30, 45 and 60 seconds. All the samples had promising surface structure and low reflection, ≤1%. The samples with shortest (15s) and longest (60s) deposition time had the most promising cross-section structures. However, the intermediate times (30s and 45s) were assumed to have been destroyed when preparation for the cross-section images, making these results misleading. A passivation layer of silicon nitride was deposited with PECVD with four different deposition times; 60, 120, 180 and 240 seconds. The samples with the shortest deposition times (60s and 120s) kept the same low reflection, below 2%, and BSiS after deposition. A passivation layer of alumina was successfully deposited chemically by dip coating and annealing of the wafer at 600°C for 3 hours. Ag plasmonic nanoparticles were mixed into the alumina solution and passivated with the same chemical production steps as the alumina passivation layer without Ag nanoparticles. The Ag nanoparticles was observed and verified with TEM. Low reflection, less than 1%, and the BSiS was kept after deposition of the passivation layer, both with and without Ag nanoparticles.

Transparent conducting oxides have a unique combination of properties as they are both optical transparent in the visible region of the electromagnetic spectrum, and obtain a near-metallic conductivity. This makes them extensively used in a wide variety of technological applications. The industrial demand for developing better, cheaper, and faster methods for producing these materials is increasing continuously. Thus, the motivation for this master thesis is to find a cheaper and faster way to produce transparent conductive oxides while still retaining the optoelectronic properties. A possible way of doing this is by replacing the conventional furnace heat-treatment step of sol-gel derived transparent conductive oxides with photochemical activation. The aim of this work is hence to compare the quality of sol-gel derived indium tin oxide and indium zinc oxide thin films cured using thermal and ultraviolet radiation methods.Indium tin oxide and indium zinc oxide thin films were prepared by spin coating a sol synthesized by an environmental friendly Pechini method onto glass and silicon substrates. The thin films were subsequently characterized with respect to crystal structure, morphology, optical properties, and electrical properties.The thermally cured indium tin oxide and indium zinc oxide thin films obtained a non-directional phase pure cubic bixbyite crystal structure, while the ultraviolet curing at room temperature and 150 °C gave an amorphous structure. By studying the morphology of the thin films it could be observed that the thermal curing gave the highest homogeneity, while the ultraviolet curing at 150 °C gave the lowest homogeneity. The same trend was also found for surface roughness, where the lowest roughness was obtained for the thermally cured films. The thin films obtained a high optical transparency with an average value of 88-97 % in the visible region of the electromagnetic spectrum. No clear trend could be seen with regards to the effect of the different curing methods on the absolute value of the transparency, whereas an evident trend was seen for the curve shape. The transmission curves had an absorption band edge at about 300 nm, and a band gap of 3.8 eV and 3.7 eV was observed for indium tin oxide and indium zinc oxide, respectively. The optical constants refractive index and extinction coefficient indicates a difference in the optical properties for indium tin oxide and indium zinc oxide. For the thermally cured indium tin oxide thin films the lowest resistivity values obtained on glass and silicon substrates were 2.8×10-3 Ω cm and 2.2×10-3 Ω cm, respectively, while the lowest resistivity values obtained for the indium zinc oxide thin films on glass and silicon substrates were 0.4 Ω cm and 0.1 Ω cm, respectively. It was not possible to obtain resistivity measurements for any of the ultraviolet curing methods, indicating that these films are non-conducting. This is most likely due to incomplete decomposition of organics in the thin films.

In this thesis, an improved Hummers method is used to produce graphene oxide, while thermal treatment has been used as the reduction process to form reduced graphene oxide. This modified version of Hummers method differs from the original one by the exclusion of NaNO3. This modification eliminates the evolution of NO2/N2O4 toxic gasses.Several syntheses are done, where parameters such as particle size and oxidation time are varied. In addition, the thermal reduction process has also been investigated, and different final temperatures, heating rates and atmospheres are carried out in order to find the best procedure. Finally, the dispersibility was tested for graphite, graphene oxide and reduced graphene oxide, as solubility is an essential property when considering the use of graphene in battery applications. All samples, including graphite, graphene oxide and reduced graphene oxide have also been characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). From the XRD results it is found that both the particle size and oxidation time are crucial in order to produce fully oxidized graphite. This was only obtained by using graphite powder smaller than 50 µm and an oxidation time of 5 days. Furthermore, the thermal reduction is also a critical step in the approach to successfully reduce graphene oxide, and it is found that the heating rate has to be 5 °C/s up to at least 900 °C in Ar/H2 (5% H2) gas, and the sample needs to be held at this temperature for 30 minutes. Too slow heating will not create enough pressure inside the sample, which is necessary to overcome the van der Waals forces between the graphene layers. The FTIR results showed that the oxygen containing functional groups attached to the graphene sheets were ketones, epoxy groups, carboxylic acids and hydroxyls. These groups make the graphene oxide soluble. However, these groups are removed during reduction, and hence the reduced graphene oxide becomes insoluble.This work clearly show that the various parameters are very important to control in order to obtain the desired product and that the end result is highly affected by the synthesis route.

By applying a texture to the front surface of solar cells, less light may be reflected and the incoming light may be given a longer path length inside the solar cell causing a better light absorbance for the solar cell. The textured layer is today made by etching with an acidic etch with a large part hydrogen fluoride. In the future a more environmental approach for creating textured solar cells may be favoured. There are many ways of creating textured surfaces, one of them are by imprinting the surface by a template, and remove the template when the process is completed.In this project the diatom species Coscinodiscus walesii and an undefined Coscinodiscus species were cleaned and processed for investigation. The work done can be divided into four tasks. The first was characterisation and investigation of the pore structure. The second were manufacturing and characterisation of gold for use as templates. The third were deposition and characterisation of thin films of silicon and silicon nitride on diatom frustules. The last part were to make structures are very similar to solar cells with diatom frustules incorporated into them.The diatom frustules were characterised by SEM and the pore structure were cut through with FIB to characterise the structure. There were structural differences between the two species. The Coscinodiscus walesii was grown in a cultivation chamber, and lacked the circular inner pore structure which the undefined Coscinodiscus species had. This was the only real difference between the two species.On the cultivated species were deposited a gold film, which a small rectangle were lifted off by a tungsten needle in FIB. The small rectangle were characterised with the SEM-column in a dual beam FIB. Pore structures down to 40 nm were replicated by the gold film lifted off the frustule. By depositing a relatively thick film of gold on a glass substrate covered with diatom frustules and dissolving the glass substrate and diatom frustules with hydrogen fluoride, a template were made with a replication of the diatom frustule pore structure.Silicon and silicon nitride were deposited on diatom frustules and characterised with FIB to investigate how those materials followed the frustule topography. A good conformity of films made of those materials was confirmed, and 4 different samples which were similar to solar cells were manufactured and characterised by light microscopy, SEM and FIB. Two samples were made to be similar to crystalline silicon solar cells. One had dried frustules on top of a silicon surface and the entire surface of the sample were coated with silicon nitride, a blue colour were observed in the entire surface and the silicon nitride had also been deposited on the diatom frustules. For the other sample similar to crystalline silicon solar cells another layer were deposited between the frustule and the silicon substrate. The double silicon layer made the sample surface yellow, the diatom frustules did not get darker due to a layer above and a layer beneath them. Only in some places where the frustules had loosened from the sample the sample were blue as the silicon nitride layer were the same as a single layer of silicon nitride. For the last two samples, thin film solar cell structures based on amorphous silicon deposited with PECVD were made. A sample there a aluminum coating were deposited on a glass substrate and diatom frustules were dried on top of the aluminum coating, afterwards a 5 µm thick film of amorphous silicon were deposited. SEM images showed that the film were distributed even across a diatom frustule and a light microscopy investigation showed that light were spread when it hit the diatom frustules, hence creating a longer mean path through the solar cell.