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The development of new semiconductor materials is one of the prime targets for the microelectronics industry. Tin disulphide (SnS2) is one such semiconductor material. It has a two dimensional layered structure which defines its chemical and physical properties. Currently no process has been developed to create SnS2 films with high structural quality at an industrial level. Chemical vapour deposition (CVD) is one technique that could offer an answer to this problem. To develop such a CVD process, it is necessary to have a good understanding of the mechanisms (nucleation and growth) that define said process. This dissertation, investigates the nucleation and growth of SnS2 using a SnCl4 / H2S CVD process for SnS2 on SiO2 wafers. The first part of experiments consists of the investigation of the temperature range in which SnS2 can be grown. To this end, Rutherford backscattering spectroscopy (RBS) is used to quantify the amount of deposited SnS2 . Various other techniques, e.g. Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), are used to examine the composition, phase and morphology of the SnS2 samples. It is found that in a temperature range of 300 to 400 ◦C SnS 2 deposition is possible for a SnCl4 / H2S ratio of 1/10, and that at 400 ◦C the films show the best crystal orientation. The second part of experiments looks at the nucleation and growth of SnS2 for CVD at 400 ◦C. The growth at 400 ◦C is followed using a.o. atomic force microscopy (AFM) for deposition times from five seconds to half an hour. A growth model is proposed, which consists of two growth regimes. The first regime consists of the nucleation on the SiO2 substrate and growth of the formed grains up to an incomplete layer closure, with a preferential lateral growth. A delayed growth model is proposed describing the formation of amorphous 3D islands, followed by crystallisation and lateral growth. The second regime describes the formation of a rough SnS2 layer via a 3D-growth. This regime is characterised by the formation of pyramidal like spirals, combined with growth of holes in the SnS2 film. It is concluded that the growth rate is too high. The surface diffusion of adatoms and their lattice incorporation rate is too low, compared to the adsorption rate of adatoms, to allow SnS 2 to grow via a 2D mechanism. For that reason, it is proposed that the main focus of further research should be; to decrease the growth rate of SnS 2 , and thus allow a more controlled and 2D growth.

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Starch, found in many plants, is a complex carbohydrate that serves as a source of energy. Next to the two main components: amylose (AM) and amylopectin (AP), it also has noncarbohydrate components present such as lipids, proteins, ... AM is a linear polymer containing α-(1,4)-glycosidic linkages that can form inclusion complexes with lipids or salicylic acid (obtained from sodium salicylate (NaSal)). AP, which is highly branched, also contains α-(1-6)-glycosidic linkages. Native maize starch has A-type crystallinity through the AP chains that are crystallized in a monoclinic lattice. The presence of these inclusion-complexes leads to V-type crystallinity. Upon heating starch in the presence of water, starch gelatinization occurs in which starch granules absorb water, swell, and burst, releasing AM and AP molecules into the medium. This will lead to the loss of their semi-crystalline structure which can be observed with small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). The gelatinization temperature (Tgel) can change due to the amount of water present or certain additives, like glucose or NaSal. These changes can be monitored with differential scanning calorimetry (DSC). Glucose is known for increasing Tgel while the hydrotrope (NaSal), an organic molecule that enhances solubility, decreases it. The amount of water will change the shape of the DSC peaks. In excess water, only one peak is formed, G endotherm, while in limited water, two peaks are formed, G and M1 peaks. An M2 peak is seen in the presence of AM-inclusion complexes. This research can be interesting as starch is crucial in the food industry but also in e.g. medicines, glue, etc. The search for less sugar in food and baked goods is nowadays a ‘hot topic’, but the amount of sugar influences the gelatinization temperature which can alter the final baked product. For glues and the other mentioned industries, it can be beneficial to lower the gelatinization temperature (e.g. addition of NaSal) so no heating is required. This research shows transient gelatinization stages in excess and limited water conditions in which part of the semicrystalline blocklets are converted to fully gelatinized starch while others remain as layered stacks in which the dense layers are ordered like smectic liquid crystals. In excess water conditions granules in the transient stage rapidly convert into fully gelatinized starch. However, in limited water conditions, the gelatinization process is arrested up to when gelatinization is resumed at higher III temperatures. At first sight, the involvement of a liquid crystalline state aligns with the side-chain liquid crystalline polymer (SCLP) model. However, unlike the SCLP model, the G and M1 endotherms do not seem to be strictly coupled with a helix-helix dissociation and a subsequent helix-coil transition. The double melting behaviour under limited water conditions thus seems to be related to a temporary arrest rather than to a split into two mechanistically different gelatinization steps (dissociation and helix unwinding). As expected, glucose indeed raises the gelatinization temperature while NaSal decreases it down to room temperature when enough NaSal is added. The glucose molecules, that are dissolved in water, seem to penetrate the starch granules when the granules are submerged into the aqueous glucose solution.

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Microplastic pollution is one of the most critical environmental issues in the world right now. Many studies about human exposure to these micro-and nanoplastics (MNP) and the toxic effects they can cause are being conducted at this moment. Quantification and identification of these MNP lie at the bottom of solving this global problem. The most popular identification methods are Fourier-transform infrared spectroscopy and Raman spectroscopy. These techniques are lacking in non-destructive analysis with high sensitivity and low background noise. This thesis aims to develop an optical spectroscopy method to detect and identify microplastics after staining with Nile Red. The latter is a lipophilic solvatochromic dye. Staining will cause the particle to fluoresce, with its emission spectrum depending on its polarity. More polar plastics will have a more red-shifted emission maximum. Via hyperspectral analysis, the MNP can be identified based on this spectrum. Fluorescence lifetime imaging microscopy is also implemented. The fluorescence lifetime is the time that a fluorophore spends in the excited state, after absorbing a photon, before returning to the ground state. The lifetime depends on the fluorophore's micro-environment and therefore is also different for each MNP type. Differentiation is possible based on this lifetime value, but a graphical, fit-free phasor approach is also used. This allows for the mapping of the lifetime distribution in an image. When two different MNP types are present in one sample, they will each have a separate distribution cloud on the phasor plot, allowing for the graphical distinguishment of MNP. The plastics used are PP, PVC, HDPE, PET, and PS, these samples contain a range of shapes and sizes. A bought suspension of pure PS polymer particles of a fixed shape and size of 0,6 μm was also examined. The spectral data were processed in two ways. By calculating a ‘weighted average’ with the intensity values at each wavelength. This resulted in each MNP being attributed a weighted average value. After recording spectra of different particles, a statistical analysis, ANOVA and t-test, was done. This showed that the weighted averages of PP & HDPE and PS (self-made) & PVC do not differ significantly. The second option is through comparing the spectra themselves, using a relative similarity percentage. Because of the low similarity MNP gave when compared with themselves, only MNP with a significantly large similarity percentage could be distinguished. The same statistical tests were done on lifetime data. Measurements done on different particles of the same plastic showed that only HDPE & PET lifetimes did not differ significantly. Multiple measurements done on the same particle showed slightly different lifetimes. It could be concluded that HDPE & PET and PS (self-made and 0,6 μm) & PET cannot be differentiated. Finally, phasor plot analysis of samples containing two different plastics showed a possibility of recognizing MNP types based on the location of their phasor cloud on a phasor plot. When combining these two techniques, making use of the ’weighted average’ value and lifetime analysis, it could be possible to identify each plastic. The combination with similarly weighted averages, PP & HDPE give significantly different fluorescent lifetimes values and are possible to separate on a phasor plot. Still, both techniques have some flaws and improvement is possible.

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Semiconductors and semiconductor materials have proven themselves to be an integral cornerstone of modern technological achievements and advancements. From the first transistors to the cutting-edge solar cells and LEDs of today, they have revolutionised materials science and engineering. In pushing for materials with higher efficiencies, superior opto-electronic properties and longer operational lifetimes, perovskites have risen to the forefront of semiconductor developments. Leading to record-breaking efficiencies in devices, this class of materials is being extensively researched. Recently many groups have started focussing on lead halide perovskites (LHPs) for use in LEDs due to their excellent properties such as high colour purity, remarkable efficiencies, solvent processability and compositional tuneability. Developments in LHPs have already provided highly efficient and relatively stable green LEDs while those of blue LEDs remain lacking. Red LEDs achieve high efficiencies but experience low operational lifetimes, limiting their use. The most common material used in red LEDs, caesium lead iodide (CsPbI3), has an inherent phase instability issue caused by the formation of non-active yellow phase at room temperature under the influence of both moisture and oxygen. A recent approach to remedying this issue is by synthesizing CsPbI3 nanocrystals. These are nanoparticles ranging from 2-20 nm in size and thus have a significantly higher surface to volume ratio; allowing for surface stabilisation methods to be employed. Long chain organic ligands are added to the synthesis which can attach to the nanocrystal surface after synthesis, encapsulating the ionic perovskite structure in an apolar organic shell, preventing moisture from entering and degrading the crystal while at the same time increasing efficiencies by filling in surface defects. The apolar shell around the nanocrystals also makes solvent processability possible since the nanocrystals can be dispersed in a solvent like hexane. This suspension can then be used to print thin films of the semiconducting material, greatly cutting fabrication costs. In this research new diammonium dopants were utilized in the synthesis of CsPbI3 nanocrystals, butanediammonium (BDA) and propanediammonium (PDA). Their ammonium group and its hydrogen bonding properties have previously been shown to lead to increased efficiencies and stabilities in perovskite materials. The doped particles were successfully prepared using the hot injection method, a technique well suited for delivering nanocrystals with narrow particle size distributions. The resulting nanocrystal suspensions were used to coat glass coverslips to measure their photoluminescence (PL) and UV-Vis spectra and left to age over a period of 9 weeks to investigate the long-term stability. UV-Vis confirmed a superior phase stability of BDA doped nanocrystals, especially in 2% and 5% molar concentrations, with yellow phase peaks appearing weeks later than in normal CsPbI3. It 4 was also found that BDA doping led to films with blue shifted emissions in 2% and 5% molar percentages while not affecting PL position in 10% concentration. The former two samples however, also showed an increase in emission width. PLQY measurements performed after synthesis also show a decrease in quantum yields to undoped CsPbI3. XRD was performed on a thin NC film and showed no change in peak position, meaning the cation did not integrate into the structure. The change

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In de maatschappij van nu is een leven zonder polymeren niet in te beelden, maar toch heeft het woord “polymeer” een slechte connotatie. Ondanks de slechte reputatie van polymeren wordt het elke dag gebruikt in elk huishouden en is het ook aanwezig in vele industriële processen. Deze polymeren bestaan uit bouwstenen die aan elkaar gekoppeld zijn en zo een ketting vormen. Door de natuur geïnspireerd hebben polymeer chemisten om perfecte controle te krijgen over de sequentie van deze bouwstenen in de ketting (sequentie gedefinieerde polymeren). Verscheidene methoden zijn ontwikkeld om deze sequentie gedefinieerde polymeren te synthetiseren. Meer recent is de focus verschoven naar polymeren die bestaan uit een afwisselende enkele en dubbele binding, omdat deze aantrekkelijke elektronische eigenschappen bevatten. Deze worden geconjugeerde polymeren genoemd. In deze thesis is een nieuwe strategie ontwikkeld om geconjugeerde polymeren te ontwikkelen met een perfecte controle over de sequentie van de bouwstenen wat sequentie gedefinieerde geconjugeerde polymeren (SDCP) wordt genoemd. Deze strategie gebruikt twee verschillende reacties om de bouwstenen aan elkaar te koppelen. Bij elke reactie wordt de ketting met één monomeer verlengt waarbij telkens een differentiatie kan ingebouwd worden. Dit zal gedaan worden door gebruik te maken van twee verschillen zijketens. Voor de reacties zijn er twee verschillend bouwstenen nodig, dus voor elke zijketen zijn er twee nodig en in het totaal moeten er dus vier verschillende bouwstenen worden gemaakt. Extra bouwstenen zijn nog nodig om de synthese van de SDCPen te starten (startblok). Deze startblokken bezitten maar één dat kan reageren in één van de reacties en een andere plaatst is beschermd. Hierna kan één van de reactie gebruikt worden om een startblock te koppelen aan een bouwsteen dat kan verder koppelen met een ander bouwsteen via de andere reactie. De twee reactie worden alternerend gebruikt om een grote ketting te bouwen (SDCP). De vier bouwstenen zijn succesvol gesynthetiseerd alsook twee efficiënte startblokken. Één van deze startblokken kan reageren in de ene reactie en de andere startblok kan reageren in de andere reactie. Het eerste startblok is succesvol gekoppeld met twee extra bouwstenen maar dit resulteerde in de vorming van een mengeling van twee producten en de opzuivering van de eerste reactie was zeer langdurig. Het andere startblok is succesvol gekoppeld met een bouwsteen en was gemakkelijk op te zuiveren. Nadien kon de bescherming van het startblok er ook gemakkelijk afgehaald worden.