Novel Materials and Deposition Techniques for Solution Processed Solar Cells

Whilst many advances have been made in the field of solution processed solar cells (SPSCs), there is still much work to be done if they are to fulfil their potential and reduce the cost of commercial photovoltaic devices. This thesis aims to assist in moving towards this objective by investigating ways to overcome some of the barriers to the commercialization of SPSCs. Such barriers include the costly and mechanically brittle electrode material of indium tin oxide, the use of solution deposition techniques which are not compatible with large-scale production, and a lack of understanding of the properties of promising new semiconducting materials such as organometal halide perovskites. In this work a novel indium-free multilayer semi-transparent electrode has been fabricated and incorporated as the anode in polymer solar cells. Whilst molybdenum oxide is typically used as the ‘seed layer’ material in such trilayer structures, its replacement with tellurium dioxide has been found to lead to an enhanced transmittance in the optimised electrodes and to an increased short circuit current when such electrodes are employed in polymer solar cells. The roll-to-roll compatible deposition technique of ultrasonic spray-coating has, for the first time, been successfully used for the fabrication of films of the organometal trihalide perovskite CH3NH3PbI3-xClx. Such films were subsequently successfully employed as the active layer in planar solar cells. This deposition technique is then extended to hole transporting and electron transporting materials in order to move towards a fully spray-deposited solar cell. Finally, a combination of structural investigation techniques have been employed to monitor the formation of the perovskite CH3NH3PbI3-xClx during thermal annealing of a precursor film. In-situ X-ray scattering measurements are used together with ex-situ scanning electron microscopy in order to correlate the evolution of the film during annealing to solar cell performance. In addition, the activation energy for the transition from precursor to perovskite has been calculated

Peer role-play and standardised patients in communication training: a comparative study on the student perspective on acceptability, realism, and perceived effect

<p>Abstract</p> <p>Background</p> <p>To assess the student perspective on acceptability, realism, and perceived effect of communication training with peer role play (RP) and standardised patients (SP).</p> <p>Methods</p> <p>69 prefinal year students from a large German medical faculty were randomly assigned to one of two groups receiving communication training with RP (N = 34) or SP (N = 35) in the course of their paediatric rotation. In both groups, training addressed major medical and communication problems encountered in the exploration and counselling of parents of sick children. Acceptability and realism of the training as well as perceived effects and applicability for future parent-physician encounters were assessed using six-point Likert scales.</p> <p>Results</p> <p>Both forms of training were highly accepted (RP 5.32 ± .41, SP 5.51 ± .44, n.s.; 6 = very good, 1 = very poor) and perceived to be highly realistic (RP 5.60 ± .38, SP 5.53 ± .36, n.s.; 6 = highly realistic, 1 = unrealistic). Regarding perceived effects, participation was seen to be significantly more worthwhile in the SP group (RP 5.17 ± .37, SP 5.50 ± .43; p < .003; 6 = totally agree, 1 = don't agree at all). Both training methods were perceived as useful for training communication skills (RP 5.01 ± .68, SP 5.34 ± .47; 6 = totally agree; 1 = don't agree at all) and were considered to be moderately applicable for future parent-physician encounters (RP 4.29 ± 1.08, SP 5.00 ± .89; 6 = well prepared, 1 = unprepared), with usefulness and applicability both being rated higher in the SP group (p < .032 and p < .009).</p> <p>Conclusions</p> <p>RP and SP represent comparably valuable tools for the training of specific communication skills from the student perspective. Both provide highly realistic training scenarios and warrant inclusion in medical curricula. Given the expense of SP, deciding which method to employ should be carefully weighed up. From the perspective of the students in our study, SP were seen as a more useful and more applicable tool than RP. We discuss the potential of RP to foster a greater empathic appreciation of the patient perspective.</p

Caenorhabditis elegans N-glycan Core β-galactoside Confers Sensitivity towards Nematotoxic Fungal Galectin CGL2

The physiological role of fungal galectins has remained elusive. Here, we show that feeding of a mushroom galectin, Coprinopsis cinerea CGL2, to Caenorhabditis elegans inhibited development and reproduction and ultimately resulted in killing of this nematode. The lack of toxicity of a carbohydrate-binding defective CGL2 variant and the resistance of a C. elegans mutant defective in GDP-fucose biosynthesis suggested that CGL2-mediated nematotoxicity depends on the interaction between the galectin and a fucose-containing glycoconjugate. A screen for CGL2-resistant worm mutants identified this glycoconjugate as a Galβ1,4Fucα1,6 modification of C. elegans N-glycan cores. Analysis of N-glycan structures in wild type and CGL2-resistant nematodes confirmed this finding and allowed the identification of a novel putative glycosyltransferase required for the biosynthesis of this glycoepitope. The X-ray crystal structure of a complex between CGL2 and the Galβ1,4Fucα1,6GlcNAc trisaccharide at 1.5 Å resolution revealed the biophysical basis for this interaction. Our results suggest that fungal galectins play a role in the defense of fungi against predators by binding to specific glycoconjugates of these organisms

Indium-free multilayer semi-transparent electrodes for polymer solar cells

We have explored the fabrication of indium-free electrodes for use in a PCDTBT:PC70BM organic photovoltaic (OPV) device, and compare different multilayer electrodes as the device anode. Two oxide/metal/oxide structures were investigated that consisted of MoO3/Ag/MoO3 (MAM) and TeO2/Ag/MoO3 (TAM) multilayers. Using scanning electron microscopy measurements, we find that the electrode utilising a TeO2 seed layer encouraged the growth of a more continuous silver layer at low film thickness relative to an MoO3 seed layer, and thus combines enhanced optical transmission (by around 7%) with low sheet resistance (14 Ω/□). This enhanced optical transmittance results in an increased short-circuit current in photovoltaic cells, with TAM-based devices having a power conversion efficiency around 6% higher than those fabricated using a comparable MAM electrode

Land–sea correlations in the Australian region: 460 ka of changes recorded in a deep-sea core offshore Tasmania. Part 2: the marine compared with the terrestrial record

We present an array of new proxy data and review existing ones from core Fr1/94-GC3 from the East Tasman Plateau. This core is positioned at the southern extreme of the East Australia Current and simultaneously records changes in both oceanography and environments both in offshore and in southeastern Australia. Microfossils, including planktonic and benthic foraminifera, ostracods, coccoliths and radiolarians, were studied to interpret palaeo-oceanographic changes. Sea-surface temperature was estimated using planktonic foraminifera, alkenones and radiolaria. From the silicate sediment fraction, the mean grain size of quartz grains was measured to detect the changes in wind strength. An XRF scan of the entire core was used to determine the elemental composition to identify provenance of the sediment. We also compare these data with a pollen record from the same core provided in an accompanying article that provides the longest well-dated record of vegetation change in southeastern Australia. In an area of slow sedimentation, Fr1/94-GC3 provides a continuous record of change in southeastern Australia and the southern Tasman Sea over approximately the last 460 ka. We determine that the East Australian Current varied in intensity through time and did not reach the core site during glacial periods but was present east of Tasmania during all interglacial periods. The four glacial–interglacial periods recorded at the site vary distinctly in character, with Marine Isotope Stage (MIS) 9 being the warmest and MIS 5 the longest. Through time, glacial periods have progressively become warmer and shorter. Deposition of airborne dust at the core site is more substantial during interglacial periods than glacials and is believed to derive from mainland Australia and not Tasmania. It is likely that the source and direction of the dust plume varied significantly with the wind regimes between glacials and interglacials as mean effective precipitation changed.The core was obtained during cruise Fr1-94 with the RV Lady Franklin which was funded by the Australian National Facility through a grant awarded to De Deckker. The original scientific crew consisted of Michael Ayress, Timothy Barrows, Leanne Armand [n ee Dansie], Chikara Hiramatsu, the late Jean Jacques Pichon, Stefan Nees, Tony Rathburn and Patrick De Deckke

Recent progress and challenges of organometal halide perovskite solar cells

We review recent progress in the development of organometal halide perovskite solar cells. We discuss different compounds used to construct perovskite photoactive layers, as well as the optoelectronic properties of this system. The factors that affect the morphology of the perovskite active layer are explored, e.g. material composition, film deposition methods, casting solvent and various post-treatments. Different strategies are reviewed that have recently emerged to prepare high performing perovskite films, creating polycrystalline films having either large or small grain size. Devices that are constructed using meso-superstructured and planar architectures are summarized and the impact of the fabrication process on operational efficiency is discussed. Finally, important research challenges (hysteresis, thermal and moisture instability, mechanical flexibility, as well as the development of lead-free materials) in the development of perovskite solar cells are outlined and their potential solutions are discussed

Aquacultured Rainbow Trout (Oncorhynchus mykiss) Possess a Large Core Intestinal Microbiota That Is Resistant to Variation in Diet and Rearing Density

As global aquaculture fish production continues to expand, an improved understanding of how environmental factors interact in fish health and production is needed. Significant advances have been made toward economical alternatives to costly fishmeal-based diets, such as grain-based formulations, and toward defining the effect of rearing density on fish health and production. Little research, however, has examined the effects of fishmeal- and grain-based diets in combination with alterations in rearing density. Moreover, it is unknown whether interactions between rearing density and diet impact the composition of the fish intestinal microbiota, which might in turn impact fish health and production. We fed aquacultured adult rainbow trout (Oncorhynchus mykiss) fishmeal- or grain-based diets, reared them under high- or low-density conditions for 10 months in a single aquaculture facility, and evaluated individual fish growth, production, fin indices, and intestinal microbiota composition using 16S rRNA gene sequencing. We found that the intestinal microbiotas were dominated by a shared core microbiota consisting of 52 bacterial lineages observed across all individuals, diets, and rearing densities. Variations in diet and rearing density resulted in only minor changes in intestinal microbiota composition despite significant effects of these variables on fish growth, performance, fillet quality, and welfare. Significant interactions between diet and rearing density were observed only in evaluations of fin indices and the relative abundance of the bacterial genus Staphylococcus. These results demonstrate that aquacultured rainbow trout can achieve remarkable consistency in intestinal microbiota composition and suggest the possibility of developing novel aquaculture strategies without overtly altering intestinal microbiota composition