Electric Vehicles (EVs) are active loads as they increase the demand for electricity and introduce several challenges to electrical distribution feeders during charging. Demand Response (DR) or performing load control in commercial buildings along with the deployment of solar photovoltaic (PV) and ice storage systems at the building level can improve the efficiency of electricity grids and mitigate expensive peak demand/energy charges for buildings. This research aims to provide such a solution to make EV penetration transparent to the grid. Firstly, this research contributes to the development of an integrated control of major loads, i.e., Heating Ventilation and Air Conditioning (HVAC), lighting and plug loads while maintaining occupant environmental preferences in small- and medium-sized commercial buildings which are an untapped DR resource. Secondly, this research contributes to improvement in functionalities of EnergyPlus by incorporating a 1-minute resolution data set at the individual plug load level. The research evaluates total building power consumption performance taking into account interactions among lighting, plug load, HVAC and control systems in a realistic manner. Third, this research presents a model to study integrated control of PV and ice storage on improving building operation in demand responsive buildings. The research presents the impact of deploying various combinations of PV and ice storage to generate additional benefits, including clean energy generation from PV and valley filling from ice storage, in commercial buildings. Fourth, this research presents a coordinated load control strategy, among participating commercial buildings in a distribution feeder to optimally control buildings' major loads without sacrificing occupant comfort and ice storage discharge, along with strategically deployed PV to absorb EV penetration. Demand responsive commercial building load profiles and field recorded EV charging profiles have been added to a real world distribution circuit to analyze the effects of EV penetration, together with real-world PV output profiles. Instead of focusing on individual building's economic benefits, the developed approach considers both technical and economic benefits of the whole distribution feeder, including maintaining distribution-level load factor within acceptable ranges and reducing feeder losses. / Ph. D.

Nanoparticles present a myriad of physical, optical, electrical, and chemical properties that provide valuable functionality to thin-film technologies. In order to successfully exploit these aspects of nanoparticles, appropriate dispersion and stability measures must be implemented. In this dissertation, different types of nanoparticles are coated with polymer and metallic layers to enable their effectiveness in both anti-reflection coatings (ARCs) and organic photovoltaics (OPVs). Ionic self-assembled multilayers (ISAMs) fabrication of poly(allylamine hydrochloride) (PAH) and silica nanoparticles (SiO2 NPs) results in highly-transparent, porous ARCs. However, the ionic bonding and low contact area between the film constituents lack sufficient mechanical and chemical stability necessary for commercial application. Chemical stability was established in the film by the encapsulation of SiO2 NPs by a photo-crosslinkable polyelectrolyte, diazo-resin (DAR) to make modified silica nanoparticles (MSNPs). UV-irradiation induced decomposition of the diazonium group and the development of covalent bonds with polyanions. Crosslinked MSNP/poly(styrene sulfonate) (PSS) ISAMs exhibited excellent anti-reflectivity (transmittance >98%, reflectance <0.2% in the visible range) and chemical stability against dissolution in a ternary solvent. Mechanical stability was also achieved by the incorporation of two additional PAH and poly(acrylic acid) (PAA) layers to create PAH/PAA/PAH/SiO2 NP interlayer ISAM ARCs. Thermal crosslinking of PAH and PAA facilitates the formation of covalent amide bonds between the two polyelectrolytes, as confirmed by FTIR. Since PAH and PAA are both weak polyelectrolytes, adjustment of the solution pH causes significant variations in the polymer chain charge densities. At low PAA pH, the decreased chain charge densities caused large SiO2 NP encapsulation thicknesses in the film with great mechanical stability, but poor anti-reflection (≤97% transmittance). At high PAA pH, the high chain charge densities induced thin encapsulation layers, insufficient mechanical stability, but excellent anti-reflection. At trade-off between the two extremes was founded at a PAA pH of 5.2 with excellent anti-reflection (less than 99% transmittance) and sufficient mechanical stability. The normal force required for scratch initiation was increased by a factor of seven for films made from a pH of 5.2 compared to those made from a pH of 6.0. Organic photovoltaics (OPVs) are an attractive area of solar cell research due to their inexpensive nature, ease of large-scale fabrication, flexibility, and low-weight. The introduction of the bulk heterojunction greatly improved charge transport and OPV performance by the blending of the active layer electron donor and acceptor materials, poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), into an interpenetrating network with high interfacial area between adjacent nanodomains. However, constrained active layer thicknesses restrict the total optical absorption and device performance. The localized surface plasmon resonance (LSPR) of plasmonic nanoparticles, such as anisotropic silver nanoplates (AgNPs), provides large local field enhancements and in coupling with the active layer, substantial optical absorption improvements can be realized. AgNPs were first integrated into the hole-transport layer (PEDOT:PSS) by ISAM deposition. Here, PEDOT:PSS was used as a negatively-charged ISAM layer. Encapsulation of the AgNPs by PAH (ENPs) provided a positive surface charge and allowed for the creation of ENP/PEDOT:PSS ISAMs. Stability against acidic etching by PEDOT:PSS was imparted to the AgNPs by coating the edges with gold (AuAgNPs). The AuAgNP ISAMs substantially improved the optical absorption, but were ineffective at increasing the device performance. The dispersion effects of functionalized polymer coatings on AgNPs were also deeply investigated. Functionalized AgNPs were dispersed in methanol and spin-coated onto the active layer. When the AgNPs possessed hydrophilic properties, such as unfunctionalized or functionalized by poly(ethylene glycol) methyl ether thiol (PEG-SH), they formed large aggregates due to unfavorable interactions with the hydrophobic P3HT:PCBM layer. However, the hydrophobic functionalization of AgNPs with thiol-terminated polystyrene (PS-SH) (PS-AgNPs) resulted in excellent dispersion, optical absorption enhancements, and device performance improvements. At a PS-AgNP concentration of 0.57 nM, the device efficiency was increased by 32% over the reference devices. / Ph. D. / Investigations are presented on the quality of distribution or dispersion of functional inorganic (composed of silicon dioxide or silver) particles that have dimensions of less than 100 nanometers, called nanoparticles. The nanoparticle surfaces were covered with polymer layers, where polymers are organic materials with repeating molecular structures. The study of these nanoparticle distribution effects were first examined in anti-reflection coatings (ARCs). ARCs induce transparency of windows or glasses through a reduction in the reflection of light. Here, the ARCs were fabricated as self-assembled thin-films (films with thicknesses ranging from 1 to 2000 nanometers). The self-assembly process here was carried out by immersing a charged substrate (microscope slide) into a solution with an oppositely-charged material. The attraction of the material to the substrate leads to thin-film growth. The process can continue by sequentially immersing the thin-film into oppositely-charged solutions for a desired number of thin-film layers. This technique is called ionic self-assembled multilayers (ISAMs). ARCs created by ISAM with charged polymers (polyelectrolytes) and silicon dioxide nanoparticles (SiO2 NPs) can lead to highly-transparent films, but unfortunately, they lack the stability and scratch-resistance necessary for commercial applications. In this dissertation, we address the lack of stability in the ISAM ARCs by adding additional polyelectrolyte layers that can develop strong, covalent bonds, while also examining nanoparticle dispersive properties. First, SiO2 NP surfaces were coated in solution with a polyelectrolyte called diazo-resin, which can form covalent bonds by UV-light exposure of the film. After tuning the concentration for the added diazo-resin, the coated SiO2 NPs were used to make ARCs ISAM films. The ARCs had excellent nanoparticle dispersion, high levels of transparency, and chemical stability. Chemically stability entails that the integrity of the film was unaffected by exposure to polar organic solvents or strong polyelectrolytes. In a second method, two additional v polyelectrolyte layers were added into the original polyelectrolyte/SiO2 NP design. Here, heating of the film to 200 oC temperatures induced strong covalent bonding between the polyelectrolytes. Variation of the solution pH dramatically changed the polyelectrolyte thickness, the nanoparticle dispersion, the scratch-resistance, and the anti-reflection. An optimum trade-off was discovered at a pH of 5.2, where the anti-reflection was excellent (amount of transmitted light over 99%), along with a substantially improved scratch-resistance. A change of pH from 6.0 (highest tested pH) to 5.2 (optimal) caused a difference in the scratch-resistance by a factor of seven. In these findings, we introduce stability enhancing properties from films composed purely of polyelectrolytes into nanoparticle-containing ISAM films. We also show that a simple adjustment of solution parameters, such as the pH value, can cause substantial differences in the film properties. Nanoparticle dispersion properties were next investigated in organic photovoltaics (OPVs) OPVs use semiconducting polymers to convert sunlight into usable electricity. They have many advantages over traditional solar cells, including their simple processing, low-cost, flexibility, and lightweight. However, OPVs are limited by their total optical absorption or the amount of light that can potentially be converted to electricity. The addition of plasmonic nanoparticles into an OPV device is a suitable way to increase optical absorption without changing the other device properties. Plasmonic nanoparticles, which are composed of noble metals (such as silver or gold), act as “light antennas” that concentrate incoming light and radiate it around the particle. In this dissertation, we investigate the dispersion and stability effects of polymer or metallic layers on silver nanoplates (AgNPs). The stability of the AgNPs was found to be greatly enhanced by coating the nanoparticle edges with a thin gold layer (AuAgNPs). AuAgNPs could then be introduced into a conductive, acidic layer of the OPVs (PEDOT:PSS) to increase the overall light absorption, which otherwise would be impossible with uncoated AgNPs. Next, the AgNPs were distributed on top of the photoactive layer or the layer that is responsible for absorbing light. Coating the AgNPs with a polystyrene polymer layer (PS-AgNPs) allowed for excellent dispersion on this layer and contrastingly, dispersion of the uncoated AgNPs was poor. An increased amount PS-AgNPs added on top of the photoactive layer progressively increased the optical absorption of the OPV devices. However, trends were quite different for the power conversion efficiency or the ratio of electricity power to sunlight power in the OPV device. The greatest PCE enhancements (27 – 32%) were found at a relatively low coverage level (using a solution concentration of 0.29 to 0.57 nM) of the PS-AgNPs on the photoactive layer.

With the increasing destruction of our natural environment, and with the realization that we ultimately depend upon this environment, my thesis explores the role of Architecture in designing the built environment to be harmonious with the natural one. How can Architecture be a teaching tool for the natural and built environments? Through the design of The Sun School for Environmental studies involving the integration of a building’s site, photovoltaic technology, daylighting, and natural ventilation, how can Architecture encourage a building to teach about itself? How can a building respond to its occupants, and to sun, wind, daylight and temperature? How can Architecture encourage the occupants to interact with the building, learn about it, respond to it, and consequently to increase their awareness of it? / Master of Architecture

This thesis presents novel materials for photovoltaic conversion. The materials described are solution-processable organic semiconductors and have been used in the fabrication of organic photovoltaic cells (OPVs). The widely used PEDOT:PSS layer was investigated in P3HT and PTB7 photovoltaics. By doping, the efficiencies recorded were amongst the highest reported in the field using a conventional architecture. Two low band-gap BODIPY-based polymers were introduced and shown to have properties favourable for optoelectronics. Photovoltaics consisting solely of the polymers as the active component surpassed the performance expected without the use of an acceptor, indicating ambipolar behaviour, which was verified by charge carrier mobility measurements. When blended with an acceptor, the devices demonstrated a short-circuit current density similar to that of P3HT, a well-studied and successful OPV material. They also revealed a broad spectral response and were shown to operate as photodiodes. Two small molecules containing diketopyrrolopyrrole (DPP) and BODIPY were introduced and characterised. The addition of thiophenes red shifted the absorption but did not result in a sufficient bathochromic shift. Instead, a propensity to aggregate limited the performance. PLQY measurements showed the aggregation to quench luminescence. The study demonstrated the importance of controlling aggregation for efficient devices. Two solution-processable small molecules with a germanium-bridged spiro centre were investigated, and the molecular, electrochemical and optical properties discussed. The small molecule with shorter conjugation length exhibited an interesting packing motif shown to be favourable for charge transport. The mobility measurements were an order of magnitude higher than those reported for sexithiophene, a small molecule analogue, and the same order of magnitude as P3HT. The two-dimensional charge transporting nature of the material was verified with two independent techniques: time of flight (TOF) and organic field-effect transistor (OFET) measurements. The mobility of the material was found to vary with annealing, a result of morphological changes. These were studied with optical, electron and scanning probe microscopies. By controlling the morphology with the implementation of a well-defined annealing method, it was possible to improve the performance of OFETs and planar-heterojunction OPVs. Solution-processed bulk-heterojunction OPVs were fabricated, characterised and optimised with Ge spiro molecules. A PCE similar to that of P3HT, 2.66 %, was achieved for the one, whilst a PCE of 1.60 % was obtained for the other. The results are encouraging, and there is scope for improvement by increasing the overlap between the absorption and solar spectrum, for example.

Τα φωτοβολταϊκά είναι κατάλληλες ενεργειακές συσκευές τόσο για εφαρμογή σε κεντρικές μονάδες παραγωγής ηλεκτρισμού (φωτοβολταϊκά πάρκα) όσο και σε ξεχωριστές μονάδες (κατοικίες και άλλα κτήρια). Και στις δύο αυτές περιπτώσεις, η εγκατάσταση των φωτοβολταϊκών επιδιώκεται να έχει την βέλτιστη κλίση και αζιμούθια γωνία των φβ πλαισίων, για να επιτυγχάνεται μεγιστοποίηση του παραγόμενου ηλεκτρισμού. Εκτός από τις περιπτώσεις που είναι εφικτή η βέλτιστη εγκατάσταση των φβ, υπάρχουν και περιπτώσεις που η εγκατάσταση παρουσιάζει ιδιαιτερότητα ως προς την τοποθέτηση και χρειάζεται ειδική μελέτη για την επίτευξη ικανοποιητικού αποτελέσματος. Στις περιπτώσεις αυτές και εκτός από το αυξημένο κόστος τα άλλα κριτήρια είναι κυρίως η επιλογή του κατάλληλου φβ πλαισίου και η λειτουργική και αισθητική ιδιαιτερότητα της εγκατάστασης, σε συνδυασμό με τις ενεργειακές και περιβαλλοντικές προεκτάσεις. Σκοπός της εργασίας αυτής είναι η μελέτη νέων τρόπων εγκατάστασης φωτοβολταϊκών, με την εξέταση των παραμέτρων που επηρεάζουν την ενεργειακή συμπεριφορά τους, ανάλογα του είδους και της τοποθέτησης των φβ πλαισίων, των συνθηκών θερμοκρασίας λειτουργίας, του πνέοντος ανέμου και φωτισμού και των ειδικών απαιτήσεων της εφαρμογής, στην κάλυψη των αναγκών σε ηλεκτρισμό. Ιδιαίτερη αναφορά γίνεται και στις συνέπειες από την ικανοποίηση αισθητικών απαιτήσεων των εγκαταστάσεων των φβ, επιδιώκοντας τον βέλτιστο συγκερασμό. Στην εργασία μελετάται πειραματικά και σε συνθήκες φυσικού ηλιασμού η συνεισφορά των διάχυτων και κατοπτρικών ανακλαστήρων στην ενεργειακή απόδοση των φβ, η απαγωγή θερμότητας από τα φβ με νερό ή αέρα, η εγκατάσταση των φβ σε δυσμενή ενεργειακά κλίση και αζιμούθια γωνία, η χρήση διαπερατών στο φως φβ πλαισίων, κλπ. Δοκιμάστηκαν διάφορα φβ πλαίσια (πυριτίου, CIS, λεπτού φιλμ, οργανικά, άκαμπτα, εύκαμπτα, κλπ) και προτείνονται σχεδιάσεις φβ εγκαταστάσεων για ειδικές περιπτώσεις εφαρμογών. Επιπλέον, υπολογίστηκαν και τα περιβαλλοντικά οφέλη από την ευρεία χρήση των φωτοβολταϊκών, ανάλογα με τις ιδιαιτερότητες των εφαρμογών τους. / Photovoltaics are solar energy devices suitable for applications in both central power generation units (solar farms) and in separate units (residential and other buildings). In both cases, the aim is to install the photovoltaic modules with optimum tilt and azimuth angle, so that the electrical output is maximized. However, there are times where the photovoltaic modules cannot be placed with optimum angles and special considerations must be done in order to achieve a satisfactory result. In such cases, besides the increased cost, there are other things that need to be considered, such as the selection of a suitable type of photovoltaic module, the functional and aesthetic particularities of the installation in combination with the energy and environmental implications. The aim of this thesis is to study new ways of installing photovoltaics, by examining the parameters that affect their energy behavior, depending on the type of pv module and the way they are installed, the operating temperature conditions, the wind, the lighting and the specific requirements of the installation, in order to meet the electrical needs. A particular reference is made at the consequences of satisfying the aesthetic requirements of pv installations, seeking the optimal solution between functional and aesthetic application. In this thesis, experiments are conducted in natural conditions in order to determine the effects of the sunlight contribution of diffuse and specular reflectors at the energy efficiency of photovoltaics, the heat dissipation with water or air, the installation of pv modules with an unfavorable inclination and azimuth angle, the use of transparent pv modules, etc. Furthermore, several types of pv modules are tested (silicon, CIS, thin film, organic, rigid, flexible, etc.) and suggestions are made for special applications. In addition, an estimation of the environmental benefits of the widespread use of photovoltaics is done, according to the particularities of their applications.

This thesis outlines investigations of metal oxide/organic interfaces in photo-voltaic devices. It focuses on device instabilities originating from the metal oxide layer surface sensitivity and it presents suggested mechanisms behind these in- stabilities. A simple sol-gel solution deposition technique for the fabrication of stable and highly performing transparent conducting mixed metal oxides (ZnMO) is presented. It is demonstrated that the use of amorphous, mixed metal oxides allows improving the performance and stability of interfacial charge extraction layers for organic solar cells. Two novel ternary metal oxides, zinc-strontrium- oxide (ZnSrO) and zinc-barium-oxide (ZnBaO), were fabricated and their use as electron extraction layers in inverted organic photovoltaics is investigated. We show that using these ternary oxides can lead to superior devices by: prevent- ing a dipole forming between the oxide and the active organic layer in a model ZnMO/P3HT:PCBM OPV as well as lead to improved surface coverage by a self assembled monolayer and promote a significantly improved charge separation efficiency in a ZnMO/P3HT hybrid device. Additionally a spectroscopic technique allowing a versatility of characterisa- tion for long-term stability investigations of organic solar cells is reported. A device instability under broadband light exposure in vacuum conditions for an inverted ZnSrO/PTB7:PC71BM OPV is observed. Direct spectroscopic evidence and electrical characterisation indicate the formation of the PC71BM radical an- ion associated with a loss in device performance. A charge transfer mechanism between a heavily doped oxide layer and the organic layers is suggested and dis- cussed.

This diploma thesis deals with the photovoltaic power plant in Zlín. Power plant is used for electricity supply of office building and stock. For better self-sufficiency there is designed battery system as storage for electrical energy which the object can not consume itself. In the theoretical part there are described development of photovoltaics and components used in power plants. Further there was described the building, construction of photovoltaic power plant and eventually also a subsidy program by which the project was financially supported. Main task in the practical part was to develop scripts in Matlab for evaluation of online measured data. Next point was an energetic evaluation of power plant operation. In the end there was calculated power plant return with subsidy support and without support. These calculations were done in PV SOL software. Eventually, there was evaluated how the system works and how the power generated by the photovoltaic power plant is used. In conclusion, there is summary of the measurements and calculations.

[pt] Uma arquitetura que exige uma enorme demanda de energia contraria o conceito de um Edifício de Energia Quase Zero (em inglês Nearly Zero Energy Building - NZEB). Pesquisas indicam que edifícios de alto desempenho podem ser alcançados com um design integrado que combina estratégias de eficiência energética, como vidro de alto desempenho, com energia fotovoltaica. A metodologia BIM pode incorporar a Análise de Desempenho do Edifício para apoiar a tomada de decisão de um projeto integrado, essa abordagem é considerada essencial para alcançar um NZEB bem-sucedido. A presente investigação inclui uma revisão sistemática da literatura que orientou a pesquisa. Com base na SLR, foi desenvolvido um Manual de Entrega de Informações que propõe um novo fluxo de trabalho no qual os estudos de energia são realizados nos estágios iniciais do design para alcançar projetos com maior eficiência energética e aproveitar a colaboração intrínseca à metodologia BIM. Por fim, é apresentado um experimento hipotético de um edifício comercial para ilustrar o fluxo de trabalho proposto no IDM desenvolvido. O software Autodesk Revit foi usado para modelar o edifício e a simulação energética foi realizada no software DesignBuilder. Verificou-se que, para que esses dois softwares fossem interoperáveis, o modelo precisava ser exportado do Revit no formato gbXML. As opções de design foram baseadas na proporção de janela/parede (30 por cento, 50 por cento e 100 por cento), no vidro adotado e no sistema fotovoltaico. A análise de viabilidade econômica foi realizada com base no Valor Presente Líquido e na Taxa Interna de Retorno. Os resultados indicaram que o uso da fachada norte para produção fotovoltaica combinado com o sistema fotovoltaico da cobertura forneceu um balanço de energia próximo de zero na maioria dos casos. Por fim, todos os casos analisados têm um tempo de retorno de investimento inferior a garantia do fabricante dos módulos fotovoltaicos (25 anos), exceto no caso com 100 por cento de relação janela/parede e vidro PV na fachada norte. / [en] An architecture that requires a huge energy demand goes against the concept of a Nearly Zero Energy Building (NZEB). Research on the subject indicates that high performing buildings can be achieved with an integrated design that combines energy efficiency strategies, such as high performing glass, with photovoltaic energy (PV). The Building Information Modeling (BIM) methodology can incorporate Building Performance (BP) analysis to support decision making of an integrated design, which is considered essential to achieve a successful NZEB. The present investigation includes a Systematic Literature Review (SLR) that guided the research. Based on the SLR, an Information Delivery Manual was developed that propose a new workflow in which the energy studies are performed in the early stages of design to achieve more energy efficient projects and take advantage of the collaboration intrinsic to the BIM methodology. Lastly, a hypothetical experiment of a commercial building is presented to illustrate the workflow proposed in the developed IDM. The Autodesk Revit software was used to model the building and the energy computer simulation was performed in the DesignBuilder software. It was found that for these two software tools to be interoperable, the model had to be exported from Revit in gbXML format. The design options in the experiment were based on window-to-wall ratio (30 per cent, 50 per cent and 100 per cent), on the adopted glass, and on the photovoltaic system. The economic feasibility analysis was performed based in the Net Present Value (NPV) and the Internal Rate of Return (IRR). The results indicated that the use of the north facade for PV production combining with the PV roof system provided a nearly zero energy balance in most of the cases. Finally, all cases analyzed had a payback time of less than the PV module manufacturer guarantee (25 years), except for the case with 100 per cent window-to-wall ratio and PV Glass in the north facade.

It is of paramount importance to our society that the environment, life style, science and amusement flourish together in a balanced way. Some trends in this direction are the increased utilization of renewable energy, like solar photovoltaics; better health care products, for example advanced biosensors; high definition TV or high resolution cameras; and novel scientific tools for better understanding of scientific observations. Advancement of micro and nanotechnologies has directly and positively impacted our stance in these application domains; one example is that of vertical periodic or aperiodic nano or micro pillar assemblies which have attracted significant research and industrial interest in recent years. In particular, Si pillars are very attractive due to the versatility of silicon. There are many potential applications of Si nanopillar/nanowire assemblies ranging from light emission, solar cells, antireflection, sensing and nonlinear optical effects. Compared to bulk, Si pillars or their assemblies have several unique properties, such as high surface to volume ratios, light localization, efficient light guiding, better light absorption, selective band of light propagation etc.      The focus of the thesis is on the fabrication of Si pillar assemblies and hierarchical ZnO nanowires on Si micro structures in top-down and bottom-up approaches and their optical properties and different applications. Here, we have investigated periodic and aperiodic Si nano and micro structure assemblies and their properties, such as light propagation, localization, and selective guiding and light-matter interaction. These properties are exploited in a few important optoelectronic/photonic applications, such as optical biosensors, broad-band anti-reflection, radial-junction solar cells, second harmonic generation and color filters.         We achieved a low average reflectivity of ~ 2.5 % with the periodic Si micropyramid-ZnO NWs hierarchical arrays. Tenfold enhancement in Raman intensity is also observed in these structures compared to planar Si. These Si microstructure-ZnO NW hierarchical structures can enhance the performance and versatility of photovoltaic devices and optical sensors. A convenient top-down fabrication of radial junction nanopillar solar cell using spin-on doping and rapid thermal annealing process is presented. Broad band suppressed reflection, on average 5%, in 300- 850 nm wavelength range and an un-optimized cell efficiency of 6.2 % are achieved. Our method can lead to a simple and low cost process for high efficiency radial junction nanopillar solar cell fabrication.            Silicon dioxide (SiO2) coated silicon nanopillar (NP) arrays are demonstrated for surface sensitive optical biosensing. Bovine serum albumin (BSA)/anti-BSA model system is used for biosensing trials by photo-spectrometry in reflection mode. Best sensitivity in terms of limit of detection of 5.2 ng/ml is determined for our nanopillar biosensor. These results are promising for surface sensitive biosensors and the technology allows integration in the CMOS platform.         Si pillar arrays used for surface second harmonic generation (SHG) experiments are shown to have a strong dependence of the SHG intensity on the pillar geometry. The surface SHG can be suitable for nonlinear silicon photonics, surface/interface studies and optical sensing.         Aperiodic Si nanopillar assemblies in PDMS matrix are demonstrated for efficient color filtering in transmission mode. These assemblies are designed using the ‘‘molecular dynamics-collision between hard sphere’’ algorithm. The designed structure is modeled in a 3D finite difference time domain (FDTD) simulation tool for optimization of color filtering properties. Transverse localization effect of light in our nanopillar color filter structures is investigated theoretically and the results are very promising to achieve image sensors with high pixel densities (~1 µm) and low crosstalk. The developed color filter is applicable as a stand-alone filter for visible color in its present form and can be adapted for displays, imaging, smart windows and aesthetic applications. / <p>QC 20160407</p>

This thesis details the development of a novel photovoltaic device based on organometal halide perovskites. The initial focus of this thesis begins with the study of lighttrapping strategies in solid-state dye-sensitised solar cells (detailed in chapter 3). While I report enhancement in device performance through the application of near and far-field light-trapping techniques, I find that improvements remain step-wise due to fundamental limitations currently employed in dye-sensitised solar cell technology— notably, the available light-sensitising materials. I found a promising yet under researched family of materials in the methyl ammonium tri-halide plumbate perovskite (detailed in chapter 4). The perovskite light-sensitiser was applied to the traditional mesoscopic sensitised solar cell device architecture as a replacement to conventional dye yielding world-record breaking photo-conversion e!ciencies for solid-state sensitised solar cells as high as 8.5%. The system was further developed leading to the conception of a novel device architecture, termed the mesoporous superstructured solar cell (MSSC), this new architecture replaces the conventional mesoporous titanium dioxide semiconductor with a porous insulating oxide in aluminium oxide, resulting in very low fundamental losses evidenced through high photo-generated open-circuit voltages of over 1.1 V. This development has delivered striking photo-conversion ef- ficiencies of 10.9% (detailed in chapter 6).