Search

Fluorine doped tin oxide thin films (SnO2:F) are widely used as transparent conductive oxide electrodes in thin-film solar cells because of their good electrical and optical properties. Thus, the surface morphology has an important influence on the optical properties of SnO 2 thin films. On a rough surface light is diffusely scattered, which extends the optical path of light inside the active layer of the solar cell and in that way improves light absorption and solar cell conversion efficiency. In this work, we investigated the surface morphology of undoped and doped SnO 2 thin films and its influence on the optical properties of the films. We have compared and analysed the results obtained by several complementary methods for thin film surface morphology investigation: atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and grazing-incidence small-angle X-ray scattering (GISAXS). Based on the AFM, SEM and TEM results, we propose a theoretical model that reproduces well the GISAXS scattering patterns.

Eduarda Fernandes,1,2 Sofia Benfeito,3 Fernando Cagide,3 Hugo Gonçalves,4 Sigrid Bernstorff,5 Jana B Nieder,2 M Elisabete CD Real Oliveira,1 Fernanda Borges,3 Marlene Lúcio1,6 1Departamento de Física da Universidade do Minho, CF-UM-UP, Centro de Física das Universidades do Minho e Porto, Campus de Gualtar, Braga, 4710-057, Portugal; 2 Ultrafast Bio- and Nanophotonics Group, INL – International Iberian Nanotechnology Laboratory, Braga, Portugal; 3CIQUP/Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto, Portugal; 4Paralab, SA, Valbom, 4420-392, Portugal; 5Elettra-Sincrotrone Trieste S. C.p.A.,, Basovizza, Trieste, I-34149, Italy; 6CBMA, Centro de Biologia Molecular e Ambiental, Departamento de Biologia, Universidade do Minho, Campus de Gualtar, Braga 4710-057, PortugalCorrespondence: Marlene LúcioUniversidade do Minho, Campus de Gualtar, Braga 4710-057, PortugalEmail mlucio@fisica.uminho.ptFernanda BorgesCIQUP/Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto, PortugalEmail fborges@fc.up.ptPurpose: AntiOxCIN3 is a novel mitochondriotropic antioxidant developed to minimize the effects of oxidative stress on neurodegenerative diseases. Prior to an investment in pre-clinical in vivo studies, it is important to apply in silico and biophysical cell-free in vitro studies to predict AntiOxCIN3 biodistribution profile, respecting the need to preserve animal health in accordance with the EU principles (Directive 2010/63/EU). Accordingly, we propose an innovative toolbox of biophysical studies and mimetic models of biological interfaces, such as nanosystems with different compositions mimicking distinct membrane barriers and human serum albumin (HSA).Methods: Intestinal and cell membrane permeation of AntiOxCIN3 was predicted using derivative spectrophotometry. AntiOxCIN3 –HSA binding was evaluated by intrinsic fluorescence quenching, synchronous fluorescence, and dynamic/electrophoretic light scattering. Steady-state and time-resolved fluorescence quenching was used to predict AntiOxCIN3-membrane orientation. Fluorescence anisotropy, synchrotron small- and wide-angle X-ray scattering were used to predict lipid membrane biophysical impairment caused by AntiOxCIN3 distribution.Results and Discussion: We found that AntiOxCIN3 has the potential to permeate the gastrointestinal tract. However, its biodistribution and elimination from the body might be affected by its affinity to HSA (> 90%) and by its steady-state volume of distribution (VDSS=1.89± 0.48 L∙Kg− 1). AntiOxCIN3 is expected to locate parallel to the membrane phospholipids, causing a bilayer stiffness effect. AntiOxCIN3 is also predicted to permeate through blood-brain barrier and reach its therapeutic target – the brain.Conclusion: Drug interactions with biological interfaces may be evaluated using membrane model systems and serum proteins. This knowledge is important for the characterization of drug partitioning, positioning and orientation of drugs in membranes, their effect on membrane biophysical properties and the study of serum protein binding. The analysis of these interactions makes it possible to collect valuable knowledge on the transport, distribution, accumulation and, eventually, therapeutic impact of drugs which may aid the drug development process.Keywords: biomimetic models, biophysical profiling, drug–membrane interaction, blood–brain barrier permeability, drug distribution, small and wide-angle X-ray diffraction

Thin films comprising three-dimensional germanium (Ge) quantum dot lattices formed by nitrogen assisted magnetron sputtering deposition in alumina matrix have been deposited using magnetron sputtering deposition. Self-organized growth of Ge QDs in alumina is regarded as a combination of diffusion-mediated nucleation and enhanced nucleation probability in the troughs of the underlying substrate. We have investigated how deposition conditions affect structural properties and the quantum confinement effect. In quantum-confined semiconductors, it is possible that multiple exciton generation (MEG) would occur. Multiple exciton generation is the process where multiple pairs of electrons and holes are generated after the absorption of a single photon. This process could be particularly beneficial for solar cells where they have the potential to increase the photocurrent significantly. In this work, we have shown how the optical and electrical properties of the films, especially their photo-induced current, and quantum efficiency can be modulated by changing the deposition conditions. Moreover, a significant photo- response and effect of multiple exciton generation effects is observed.

Self-supporting thin films containing nanopores are very promising materials to be used for multiple applications. Here we present a method for the production of nanomembranes containing a 3D ordered network of nanopores in an alumina matrix, with a diameter of about 1 nm, and body centered tetragonal structure of the network nodes [1]. The material is produced by magnetron sputtering deposition of a 3D ordered network of Ge nanowires in alumina matrix, followed by a specific annealing process resulting in the evaporation of Ge. We demonstrate that the films can be easily grown on different substrates, including porous ones. We believe that these films have a potential for applications in the fields of filtration, separation and sensing.

Effect of nitrogen presence during magnetron sputtering deposition of Ge quantum dot lattices embedded in the alumina matrix was studied. Three series of samples were deposited by varying substrate temperature, nitrogen flow rate, and germanium content. The aim was to examine the effects of these parameters on the structural and optical properties of the material and the self- assembled growth regime. Special attention was devoted to the oxidation of Ge quantum dots, and their effect on the optical properties of the material. It was shown that the presence of N affects the size of Ge QDs, their oxidation, and their optical properties. Deposition temperature and Ge content also affect Ge QD sizes and consequently bandgap and optical properties. Thus, the combination of the mentioned parameters presents a powerful tool for control of the properties of the material that are important for optoelectronic applications.

Exposure to environment yields corrosion of metals, while to corrodent will increase the rate. Thereof, the development of protective coatings has been continuous industrial demand. With plethora of various mono-functional coatings, the concerns have been raised regarding their environmental acceptability, and stability. With recently developed smart coatings that bring about concepts like self-healing, and selective/multi-activity, concerns repose on difficulties to achieve complex architectures or functional groups in simple, cheap and easy-to-scale-up manner. Yet, recent activities show it is possible to exhibit multi-functionality without abovementioned discrepancies. Thereof, this investigation utilises cheap-wet-chemistry to from simple nano-architectures by “smart assembly” with functionalities comparable to those of “smart materials”. First of all, we withhold from one-pot synthesis and thereof, with the help of hydrolysis-rate-control-agents, sol-stabilisers, drying-control-agents and post-processing, the distinction of properties was maximised in each layer. Sol-gel method was utilised to tailor different (porosity or high specific surface control) but homogeneous and compatible layers that can be assembled into multifunctional composites. First, metal-contacted protection-layer was dense, crystalline, thin, i.e. barrier from both from environment and chemicals, with low porosity and SS surface, closed pores and excellent mechanical properties. Second layer was thicker, amorphous, container-type with additives, open mezzo-pores and reasonable mechanical properties. Various agents can be infiltrated. Third layer was based on core-shell particles partially penetrating/closing the pores of the 2nd layer thus blocking the infiltrated additives and partially forming additional top layer. Overall, the submicron multi-layer-coating was processed below 350°C to show crack-free, anti-corrosive and tribo-efficiency with good mechanical properties.