This thesis studies parameters influencing both the performance and stability of solid state sensitized solar cells (ssSSCs). ssSSCs benefit from their low materials and manufacturing processing costs, a consequence of using solution processed materials. However, solution processed materials are often structurally and electronically disordered. By characterizing fully operational ssSSCs and their charge transport properties, this thesis elucidates the factors limiting charge transport and proposes routes towards both improved photovoltaic conversion efficiency and long-term stability. Chapter 2 provides an explanation of the operation of ssSSCs, while Chapter 3 discusses the basic methods used in this thesis. Having set this background, Chapter 4 explores the interaction between atmospheric oxygen and charge doping mechanisms in the organic semiconductors used in ssSSCs. To understand the implications of the findings presented in Chapter 4, a new technique, “transient mobility spectroscopy”, was developed to understand the evolution of balanced charge transport behaviour of disordered semiconductors at different operating conditions in ssSSCs. This technique is presented in full in Chapter 5. The understanding gained in Chapters 4 and 5 suggest that alternative light absorbers with higher extinction coefficients may be beneficial to improving the performance of ssSSCs. Chapter 6 discusses the use of an organometal trihalide perovskite, as light absorber in ssSSCs. Using time resolved techniques, the charge transport and recombination mechanisms in various device architectures are explored, allowing suggestions to be made towards future improvements. Chapter 7 uses the technique presented in Chapter 5 to understand a rapid degradation mechanism of working ssSSCs. Particular focus is placed on the titanium dioxide charge-transporting layer. Building on this newfound understanding, two methods for attaining stable photovoltaic performance are provided, a great step forward for this technology.

The primary aim of this thesis is to explore the immunostimulatory properties of a family of layered, crystalline, inorganic materials known as layered double hydroxides (LDHs). <strong>Chapter One</strong> provides an introduction to relevant aspects of the immune system, and the context for investigating the immunostimulatory properties of inorganic materials in terms of vaccine/adjuvant formulations. The possible mechanisms of action of commercial adjuvant materials are also reviewed, and the structure, synthesis methods and applications of LDHs are discussed. <strong>Chapter Two</strong> details the controlled synthesis and characterisation of LDHs in specific particle sizes. A series of MgAl-CO3 LDHs with precisely controlled particle sizes ranging from 20 to 10000 nm were successfully synthesised, then the techniques used were extended to other compositions to create a panel of LDHs for use in subsequent Chapters. In <strong>Chapter Three</strong>, the responses of monocyte-derived dendritic cells (Mo-DC) to the LDH particle sizes discussed in Chapter Two are assessed in terms of viability, surface molecule expression, and cytokine secretion. A statistical modelling approach using the physicochemical properties of the LDHs as explanatory variables for immune responses was employed to evaluate the validity of the model formulated in the previous work, and to establish if particle size could be used to improve its predictive ability. It was found that strong relationships between LDH particle size and certain Mo-DC responses exist, and that these responses could be predicted with a high degree of accuracy. <strong>Chapter Four</strong> is concerned with the investigation of T cell responses to LDH-stimulated allogeneic Mo-DC. Various methods were used for assessing T cell division and proliferation, and a protocol for intracellular cytokine staining was developed to probe T cell polarisation. Five LDHs, which have elicited potentially interesting T cell responses in previous work, were selected for investigation. However, using the assays described, no discernible improvement in proliferation or polarisation was observed with any of the LDHs tested. <strong>Chapter Five</strong> presents an initial exploration of the interactions between LDH particles and cells. Experiments have shown that LDH particles both adhere to and are internalised by Mo-DC. Variations in the extent of internalisation with both particle size and composition were highlighted by confocal microscopy studies. Through investigations into interactions between LDH particles and the plasma membrane using protease enzymes, it was revealed that adhesion of LDH particles is partly protein-dependent. Further studies have also demonstrated a pH-dependent element to particle association with Mo-DC. Details of the experimental procedures employed are included in <strong>Chapter Six</strong>. Supplementary information referred to in the main thesis may be found in the <strong>Appendices</strong>.

Solid-state dye-sensitized solar cells (ssDSCs) offer the possibility of high power conversion efficiencies (PCEs) of over 20%. However, after more than a decade of research, devices still barely reach over 7% PCEs. In this thesis, limitations to device performance are studied in detail, and solutions for future advancement are put forward. In the first part of the thesis, factors limiting charge generation are explored by studying the crystallization environment of mesoporous TiO2 self-assembled through block copolymers. It was found that the density and distribution of sub band gap states are a function of the synthesis conditions and critically affect the performance characteristics of the self-assembled titania used in ssDSCs. As a result, the self-assembled mesoporous oxide system presented in this thesis outperforms for the first time the conventional nanoparticle based electrodes fabricated and tested under the same conditions, with demonstrated PCEs of over 5%. In chapters 6, 7, and 8, the factors limiting the diffusion length and hence, the thickness of the fabricated devices, are carefully examined. Previous literature points towards insufficient pore-filling of the hole transporting material (HTM) as the main limiting factor. In chapter 6, a pore-filling study is shown where a new technique to evaluate the pore-filling fraction of the HTM in the conventional mesoporous metal oxide electrode is also presented and conclude that sufficient pore-filling of thick films can easily be achieved. Another usual strategy to extend the electron lifetime in the devices and thus, the charge diffusion length, involving thin film coatings of insulating metal oxides is examined in chapter 7, with satisfactory results for SnO2-based ssDSCs. The diffusion length can also be extended if the factors limiting the diffusion of charges through the device are identified and removed, as presented in chapter 8. Finally, a study on the stability of the ssDSC is presented in chapter 9. The developments achieved enable long term stability to be effectively targeted, and represent a key milestone towards commercial realization of ssDSCs.

Graphene, as a recently discovered carbon allotrope, possesses with it many outstanding properties ranging from high electrical conductivity to great mechanical strength. Single layer graphene can be prepared by mechanical cleavage of graphite or by a more sophisticated method, CVD. However, the scale-up process for these preparation techniques is still unconvincing. Solution-processed graphene from exfoliation of graphite oxide on the other hand provides an alternative prospect resulting in the formation of graphene nanoplatelets (GNPs), which can be readily manipulated to tailor-suit various application demands. The main aim of the thesis is to explore the possibility and availability of this versatile method to produce graphene nanoplatelet and its composites with good all-round performance in energy and bioanalytical applications. A range of physical and chemical characterisation techniques were utilised including SEM, TEM, AFM, XPS, XRD, DLS, FTIR, Raman and UV-Vis spectroscopy in order to investigate the structural and chemical information of the graphene-based materials prepared. Functionalisation of graphene oxide with polyelectrolyte polymer could facilitate deposition of platinum nanoparticles in the formation of Pt-GNPs composites. The resultant composite was employed for bioanalytical application in the detection of an important neurotransmitter, glutamate, based on glutamate oxidase enzyme. The performance of Pt-GNPs based glutamate sensor exhibited enhanced sensitivity and prolonged stability compared to the sensors based on Pt decorated diamond or glassy carbon electrodes. The significant interfering effect from concomitant electrochemically active biological compounds associated with Pt-GNPs electrode however could be alleviated via opting for Prussian blue deposited GNPs electrode instead. The oppositely charged Pt-GNPs due to different functionalising polymers were also subject to self-assembly, which was enabled by the electrostatic interaction of the opposite charges of Pt-GNPs. The self-assembled film showed enhanced mechanical stability than the conventional drop-casted film and provided reasonably good activity towards oxidation of hydrogen peroxide. Three-component composite of graphene, nanodiamond and polyaniline was prepared via in-situ polymerisation for usage as an electrode material in electrochemical capacitors ("supercapacitors"). The addition of graphene was shown to significantly enhance specific capacitance while nanodiamond could improve the stability of the electrode by strengthening the polymer core. Another approach to produce a supercapacitor was via electrodeposition of nickel and cobalt hydroxides on graphene oxide film corporated with bicarbonate salt. The film was then subject to thermal reduction of GO and expansion of graphene layers within the film was observed. This leavening process enhanced the surface area of graphene film and thus the higher specific capacitance was obtained. The decoration of nickel and cobalt hydroxides onto the film also boosted the specific capacitance further however the poor cycling stability of the heated film still remained an issue. Graphene nanoplatelets were also used as a support for electrodeposition of Pt nanoparticles for methanol oxidation in acidic media. The preferential phase of the Pt deposited and large surface area of graphene in comparison to other carbon supports studied led to good catalytic activity being observed.

Single-molecule detection has provided insights into how molecules behave. Without the averaging effect of ensemble measurements, the stochastic behaviour of single molecules can be observed and intermediate steps in multistep transformations can be clearly detected. The single-molecule reactants range from small molecules (e.g. propene) to proteins of several tens of kDa (e.g. myosin). One single-molecule detection technique is single-channel electrical recording. This approach is based on the measurement of the transmembrane ionic current flowing through a nanoscale transmembrane pore under an applied potential. In this thesis, the protein α-hemolysin was employed as a nanoreactor. α-Hemolysin is a toxin secreted by Staphylococcus aureus. Its transmembrane pore (~100 Å in length and ≥14 Å in diameter) allows ions, water and small molecules to pass through its lumen. Under an applied potential, chemical changes in reactants attached to the internal wall of the pore modulate the flow of ions, leading to changes in the transmembrane ionic current. Analysis of this current provides information about the reaction kinetics and mechanisms. Chapter 1 – Single-Molecule Chemistry and α-Hemolysin is an introductory chapter that is divided into two parts. Section 1.1 provides an overview of the different techniques for the detection of chemical reactions at the single-molecule level. Section 1.2 gives a brief review of the protein pore α-hemolysin, including its structure, properties and various applications. Chapter 2 – S-Nitrosothiol Chemistry applies cysteine-containing α-hemolysins to study the biologically relevant chemistry of S-nitrosothiols (RSNO). RSNO are important molecules involved in cell signalling, which control physiological processes such as vasodilation and bronchodilation. Three reactions, namely transnitrosation (the transfer of the ‘NO’ group from RSNO to a thiol), S-thiolation (the formation of a disulfide from RSNO and thiol) and S-sulfonation (the generation of an S-sulfonate (RSSO₃⁻) from RSNO and sulfite ion), were investigated at the single-molecule level. The pH-dependency of the two competing reactions (transnitrosation and S-thiolation), the lifetime of the proposed transnitrosation intermediate, and nature of the chemical reaction between RSNO and sulfite (a bronchoconstrictor) were determined. Chapter 3 – Silver(I)-thiolate and cadmium(II)-thiolate complexes describes the kinetics of the formation and breakdown of these two metal-thiolate complexes. Ag⁺ and Cd²⁺ are commonly used in probing the membrane topology and gating properties of ion channels using the scanning cysteine accessibility method (SCAM). The binding of two Ag⁺ ions per thiol group and the stepwise build-up and dissociation of Cd²⁺-glutathione complexes were unambiguously characterized. Chapter 4 – Copper(II)-Catalyzed Diels-Alder Reactions reports the attempt to carry out copper(II)-catalyzed Diels-Alder reactions inside an engineered α-hemolysin. An iminodiacetate ligand was covalently attached within the lumen of the α-hemolysin pore. This ligand chelates Cu²⁺ ion, which can bind bidentate dienophiles and activate them towards Diels-Alder reaction with dienes. However, due to the ‘slow’ reaction rate of the Diels-Alder reaction (rate constant ~10⁻¹ M⁻¹s⁻) relative to the time-scale of the single-molecule experiment, we failed to observed chemical conversion at the single-molecule level. Nevertheless, the engineered metal-binding α-hemolysin may be useful for sensing molecules bearing metal-coordinating groups.

Monodispersed microgels composed of poly-acrylic acid (PAAc) and poly(N-isopropylacrylamide) (PNIPAM) interpenetrating networks were synthesized by 2-step method with first preparing PNIPAM microgel and then polymerizing acrylic acid that interpenetrates into the PNIPAM network. The semi-dilute aqueous solutions of the PNIPAM-PAAc IPN microgels exhibit an inverse thermo-reversible gelation. Furthermore, IPN microgels undergo the reversible volume phase transitions in response to both pH and temperature changes associated to PAAc and PNIPAM, respectively. Three applications based on this novel hydrogel system are presented: a rich phase diagram that opens a door for fundamental study of phase behavior of colloidal systems, a thermally induced viscosity change, and in situ hydrogel formation for controlled drug release. Clay-polymer hydrogel composites have been synthesized based on PNIPAM gels containing 0.25 to 4 wt% of the expandable smectic clay Na-montmorillonite layered silicates (Na-MLS). For Na-MLS concentrations ranging from 2.0 to 3.2 wt%, the composite gels have larger swelling ratio and stronger mechanical strength than those for a pure PNIPAM. The presence of Na-MLS does not affect the value of the lower critical solution temperature (LCST) of the PNIPAM. Surfactant-free hydroxypropyl cellulose (HPC) microgels have been synthesized in salt solution. In a narrow sodium chloride concentration range from 1.3 to 1.4 M, HPC chains can self-associate into colloidal particles at room temperature. The microgel particles were then obtained in situ by bonding self-associated HPC chains at 23 0C using divinyl sulfone as a cross-linker. The volume phase transition of the resultant HPC microgels has been studied as a function of temperature at various salt concentrations. A theoretical model based on Flory-Huggins free energy consideration has been used to explain the experimental results. Self-association behavior and conformation variation of long chain branched (LCB) poly (2-ethyloxazoline) (PEOx) with a CH3-(CH2)17 (C18) modified surface are investigated using light scattering techniques in various solvents. The polymer critical aggregation concentration (cac) strongly depends on solvent polarity, decreasing as the solvent becomes more hydrophobic.

This thesis studies quaternary chalcogenide nanocrystals and their photovoltaic applications. A temperature-dependent phase change between two distinct crystallographic phases of stoichiometric Cu₂ZnSnS₄ is investigated through the development of a one pot synthesis method. Characterisation of the Cu₂ZnSnS₄ nanocrystals was performed using absorption spectroscopy, transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). An investigation was conducted into the effects of using hexamethyldisilathiane (a volatile sulphur precursor) in the nucleation of small (<7nm), mono-dispersed and solution-stable quaternary Cu₂ZnSnS₄ nanocrystals. A strategy to synthesize high quality thermodynamically stable kesterite Cu₂ZnSnS₄ nanocrystals is established, which subsequently enabled the systematic study of Cu₂ZnSnS₄ nanocrystal formation mechanisms, using optical characterization, XRD, TEM and Raman spectroscopy. Further studies employed scanning transmission electron microscopy (STEM) energy dispersive x-ray (EDX) mapping to examine the elemental spatial distributions of Cu₂ZnSnS₄ nanocrystals, in order to analyse their compositional uniformity. In addition, the stability of nanocrystals synthesised using alternative ligands is investigated using Fourier transform infrared spectroscopy, without solution based ligand substitution protocol is used to replace aliphatic reaction ligands with short, aromatic pyridine ligands in order to further improve Cu₂ZnSnS₄ colloid stability. A layer-by-layer spin coating method is developed to fabricate a semiconductor heterojunction, using CdS as an n-type window, which is utilised to investigate the photovoltaic properties of Cu₂ZnSnS₄ nanocrystals. Finally, three novel passivation techniques are investigated, in order to optimise the optoelectronic properties of the solar cells to the point where a power conversion efficiency (PCE) of 1.00±0.04% is achieved. Although seemingly modest when compared to the performance of leading devices (PCE>12%) this represents one of the highest obtained for a Cu₂ZnSnS₄ nanocrystal solar cell, fabricated completely under ambient conditions at low temperatures.

Title: Morfology and surface chemical composition of porous silicon prepared at various conditions Author: Bc. Martin KONEČNÝ Author's e-mail: konecmar@seznam.cz Department: Department of Chemical Physics and Optics Supervisor: Doc. RNDr. Juraj Dian, CSc. Supervisor's e-mail: Juraj.Dian@mff.cuni.cz Abstract: Porous silicon is a silicon-based material prepared mainly by anodic etching of crystalline silicon in hydrofluoric acid. Physical and chemical properties of porous silicon are governed by structures with sizes of the order of ones to tens of nanometers. Properties of nanostructure material are affected - as compared to macroscopic counterparts - by quantum confinement effect and enormous internal surface. According to type of silicon substrate (type of dopant, conductivity, crystallographic orientation) and technological conditions a material with different mean size of pores (macro-, meso- and nanoporous silicon) and surface chemical composition (different ratio of Si-O and Si-H bond) can be prepared. Morphology and surface chemical composition predestinated application potential of porous silicon for sensors of chemical species by taking advantage of strong sensitivity of physical properties of silicon nanocrystals - especially of photoluminescence - on the chemical state of a surface. Detection of...

Regulation of genetically modified organisms and nanotechnology (comparison of British, Czech and Slovak legislation in the context of EU) The aim of this thesis is to first compare the british, czech and slovak legislation relating to genetically modified organisms. By the analysis of their respective features, the author points out the difficult bits and tries to look for the ideal solutions to the current problems of the european GM legislation. In spite of the fact, that the european legislation in this field is highly harmonised, there are still some areas that can be regulated by the member states as well as some holes waiting to be fixed. This thesis is composed of six main chapters which correspond to six main topics of present biotechnology legislation that are in the author's opinion the most significant. First chapter deals with the basic issues of releases of genetically modified organisms into the environment, on market, and with their contained use. Secondly, the author dissects the GM labelling and traceability legislation and shows the various thresholds of GM presence that are applicable to different areas. Third chapter then analyses the rules on co-existence between GM plants on one hand and conventional and organic plants on the other. Nextly, the unilateral acts of member...

The objective of this Ph.D. study is to explore an important and fertile research topic on the methods for synthesis of nanomaterials by homogeneous nonaqueous solution phase reaction. Research in this work focuses on synthesizing several kinds of nanomaterials in different environments and structure, including spherical nanoparticles, nanowires and core-shell structure composites We first synthesized metallic nanomaterials in this system, such as ~10 nm Fe nanoparticles, ~6 nm Au nanoparticles, and ~100 nm Bi nanoparticles, this system are the preparation for the following studies. Secondly, we synthesized bimetallic nanomaterials in this system, such as Fe50Co50 alloy and Bi doped with Mn. For FeCo alloy, after annealing at 500 °C, a pure phase of Fe50Co50 was obtained. And we first synthesized the nanowires of bismuth doped with manganese. By studying intermediates at different temperatures during the growth process of nanowires, the evolution of the crystallization of metallic products and the mechanism of the formation of the nanowires are investigated. Thirdly, we synthesized core-shell structure nanocomposites, including either gold as the shell or polymer as the shell. Au-coated magnetic Fe nanoparticles have been successfully synthesized by partial replacement reaction in a polar aprotic solvent with about 11 nm core of Fe and about 2.5 nm shell of Au. HRTEM images show clear core-shell structure with different crystal lattices from Fe and Au. SQUID magnetometry reveals that particle magnetic properties are not significantly affected by the overlayer of a moderately thick Au shell. The Aucoated particles exhibit a surface plasmon resonance peak that red-shifts from 520 to 680 nm. And Poly (Vinyl Pyrolidone) (PVP) coated iron nanoparticles also have been successfully synthesized in a polar aprotic solvent, which shows the welldefined core-shell structures. In this approach, Poly (Vinyl Pyrolidone) (PVP) was employed as the coating polymer directly coated on metallic core (iron) nanoparticles. In this work, a combination of TEM (transmission electron microscopy), EDS (Energy disperse X-ray spectroscopy), XRD (X-ray powder diffractometry), ICP (inductively-coupled plasma spectrometer), TGA (Thermogravimetric analysis), UV-visible absorption spectroscopy, IR (infrared) spectroscopy and SQUID magnetometry (Superconducting Quantum Interference Device) were employed to characterize the morphology, structure, composition and magnetic properties of the products. In summary, this Ph.D. study successfully and systematically synthesized several kinds of nanocomposites in a system. The synthetic procedure is simple, economic and easily scaled-up for further applications. And many techniques were employed to characterize the products.