Solar photovoltaics (PV) is expected to be a critical contributor to mitigating the effects of climate change by helping to satisfy net zero emissions. Since crystalline silicon-based solar cells are close to their practical efficiency limit, further reducing the balance of system (BoS) costs is only possible by increasing the cell efficiencies. The most promising candidate is perovskite/silicon (Si) tandem solar cell technology, which allows efficient solar spectrum harvesting. This relatively new technology attracts attention due to its potential to dominate the PV market; however, it also brings challenges that must be overcome, like stability and scalability concerns. This thesis project focuses on optimizing and characterizing recombination junctions (RJs) for monolithic perovskite/Si tandem solar cells aimed at improved performance and stability. Tandem solar cell PV parameter measurements, encapsulated stability measurements, and thin film characterizations are performed for RJ developments. The optimizations are performed for tandem solar cells with solution-processing and hybrid methods. Self-assembled monolayer (SAM) molecules and transparent conductive oxide (TCO) recombination layer (RL) combinations are optimized to obtain tandems with hybrid technique. In addition, the influence of the thickness of TCO RL on the tandem devices’ performance is also investigated, particularly solution-processed tandems. The improvements are observed by thinning down the thickness of TCOs regardless of the material type. 3 Characterizations revealed that ultra-thin ( 5 nm) amorphous indium zinc oxide (IZO) RL allows more workfunction shift, homogeneous surface potential distribution with SAM deposition, and better carrier recombination suppression at the perovskite/hole transport layer (HTL) interface. Ultra-thin RL idea is combined with some optical improvements in the device architecture, and stable high-efficient perovskite/Si tandem solar cells with 32.5% power conversion efficiency (PCE) and 80% fill factor (FF) values are realized. In addition, the preliminary examples of tandem devices with a larger active area (4 cm2 ) are presented. Finally, the remaining challenges and alternative concepts are also discussed.

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A stretchable silver ink was screen printed to TPU sheets, then tensile coupons of the TPU, both bare and laminated to cotton, Denim and spandex fabric, were subjected to 1000 cycles of 20% uniaxial strain. In-situ resistance measurements of printed traces were processed to generate datasets of maximum and minimum resistance per cycle. A mechanistic fit model was used to predict the resistance behavior of the ink across TPU/fabric levels. The results show that traces strained on TPU laminated to spandex (polyester) fibers had an average rate of increase in resistance significantly lower than that of traces strained on bare TPU. The variation in predicted resistance was significantly lower in the spandex group than in the TPU group. Trace width was not found to have a significant effect on the resistance behavior across TPU/fabric groups. More testing is required to understand the effect of lamination to high elasticity fabrics on resistance behavior as it relates to the viscoelastic properties of the fibers and weave structure.

The increasing role of sustainability will lead the mobility by road into a more efficient and interactive system between infrastructure, environment and vehicles. The expand of emobility based on Electric Vehicles has been restricted by numerous shortcomings such as their driving range, the battery size, the dependence on charging stations and the time required for its charging. One of the solutions to overcome these limitations is can be the construction of electrified roads. The study compares the most significant opportunities for eRoads as the solutions ofInductive Power Transfer (IPT), conductive track and pantograph in climate change aspect.This thesis is also intended to describe these systems, as they represent different ways for reach electrification of ordinary roads. IPT is a contactless solution which uses the well-known electromagnetic induction principle. Pantograph and conductive track are both conductive solutions. In the first case, it is an overhead solution and for the track, the energy is transferred to the vehicles from a continuous rail embedded in the pavement. The aim of the study is to develop an open and transparent Life Cycle Assessment (LCA)framework for electrified roads that could be used for decision support. The main objective is to build a cradle-to-grave LCA model in SimaPro for an electrified highway asphalt road in Sweden. / A fenntarthatóság, fenntartható fejlődés világszerte egyre fontosabb szerephez jut,elősegítve ezáltal azt, hogy hagyományos útburkolatok helyett hatékonyabb, interaktív rendszerek kerüljenek kiépítésre. Ezek az „okos” utak összekapcsolják az infrastruktúrát, akörnyezetet és az embert, mint járművezetőt. Jelenleg, a már hagyományosnak mondható e-közlekedésnek – mely az elektromos autók használatán alapul – számos hátrányafigyelhető meg. Többek között a korlátozott vezetési távolság és akkumulátor méret,valamint a töltési lehetőségektől és töltésidőtől való függés. Ezek leküzdésének egyik módja lehet a villamosított utak építése és elterjedése. A tanulmány célja egy nyílt, átlátható és könnyen kezelhető életciklus-elemzés (LCA) keretrendszer kiépítése a villamosított utak számára, mint döntéstámogató rendszer ajövőbeli beruházásokhoz. Ez egy svédországi villamosított autópálya, SimaPro programbanlétesített életciklus-elemzés modell építésével kerül bemutatásra. A dolgozat a három legjelentősebb típusú rendszereket hasonlítja össze a klímaváltozást befolyásoló hatások tekintetében. Ezek az indukció elvén alapuló IPT, a vezető pálya és a pantográf megoldások. A tanulmány szintén hivatott bemutatni a rendszereket, minthogyezek merőben különböző elveken alapuló megoldásokkal érik el a hagyományos utakvillamosítását. Míg elektro-mágneses töltés elvén alapuló rendszer a kontakt nélküli megoldások közé tartozik, addig a másik két rendszer álladó fizikai kapcsolatot igényel a jármű és a töltési rendszer elemei között.

As technology advances, a need for non-metal, conductive materials has arisen for several types of applications. Lithographic techniques are helpful to develop some of these applications. Such techniques require materials that are insulating and become conductive after irradiated. Composites of polyaniline in its emeraldine base form (PANI-EB) doped with photo-acid generators (PAG) become conductive upon photo-irradiation. This increase in conductivity is due to the protonation of PANI-EB. Such materials may be utilized to fabricate conducting patterns by photo-irradiation; however, the conductivity obtained by direct irradiation of PANI-EB/PAG composites is normally quite low (<10-3 S/cm) due to aggregation of highly loaded PAG. In this work, poly(ethylene glycol) (PEG), a proton transfer polymer, was added to PANI-EB/PAG. Results showed the addition of low molecular weight (MW) (550) PEG significantly enhanced the photo-induced conductivity to a level comparable to that of PANI-salt synthesized by oxidizing aniline in the presence of an acid. High MW (8000) PEG is less effective than PEG 550, and composites of PANI-EB and N-PEG-PANI showed conductivity as high as 102 S/cm after treatment with HCl vapor. The photo-induced conductivity of the N-PEG-PANI/PANI-EB/PAG composite reached 10-2-10-1 S/cm. Polychlorinated biphenyls (PCBs) are a class of chemicals with 209 different congeners, some of which are known carcinogens, and are persistent organic pollutants in the environment. After its synthesis, it was seen as a phenomenal additive in a multitude of different applications leading to the wide spread use of PCBs and a need for a safe, effective, and inexpensive remediation technique. While it is known that magnesium can degrade PCBs, the mechanism of this reaction was not well-understood. In order for magnesium to be broadly used as a remediation tool, it is necessary to fully understand how the reaction is taking place and if the PCBs are able to be fully dechlorinated into biphenyl. This research focuses on the hydrodechlorination of PCBs with zero-valent magnesium in acidified ethanol. The degradation pathways of 2, 2', 3, 5, 5', 6- hexachlorobiphenyl were investigated to determine the identity of the daughter PCBs produced, how and if they continue to be dechlorinated into biphenyl. The proton source for this hydrodehalogenation reaction was also studied using both deuterated solvent and acid to give more detail to the mechanism of this reaction.

This thesis project was executed at ABB AB. The purpose of the thesis was to formulate aselection of ionic liquids with different thickeners as greases and experimentally understand thetribological characteristics and electrical properties. The performance of four ionic liquids, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (IL6), 1-Butyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide (IL2), 1-Hexyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide (IL3), and 1-Hexyl-1-methylpyrrolidiniumbis(trifluoromethylsulfonyl)imide (IL4) and two thickeners, polytetrafluoroethylene (PTFE)powder and lithium stearate were evaluated for tribological and electrical properties. Two ionicliquids, 1-Ethyl-3-methylimidazolium dicyanamide, 1-Butyl-3-methylimidazolium dicyanamidefailed to form stable greases due to poor miscibility with the thickeners. Frictional tests for all thecomposed grease were performed and afterwards analyzed with a light optical microscope forassessment of the wear tracks. Electrical conductivity was measured with a contact resistancetest setup. Moreover, the dropping point for the greases was measured to ensure theformulations were qualified as lubricant greases. Ionic liquid greases containing PTFE as athickener show better thermal stability than those containing lithium stearate. In regards to antiwearand friction reduction, the results indicate better tribological properties for the IL3 and IL4with the 25 wt% of PTFE and lithium stearate. The electrical conductivities were similar for allthe ionic liquid grease formulations which were higher than the general purpose grease as thereference. The work has paved the way for further investigation of ionic liquid based greaseswhich show potential in mitigation of bearing current in electric machines.

Polymer-derived ceramics (PDCs) are exceptional ultra-high temperature and stable multifunctional class of materials that can be synthesized from a polymer precursor through thermal decomposition. The presented research focuses on 1-D nanofibers, 2-D films and 3-D bulk, carbon-rich silicon carbon nitride (SiCN) ceramics. 1-D nanofibers were prepared via electrospinning for light weight, flame retardant and conductive applications. The commercially available CerasetTM VL20, a liquid cyclosilazane pre-ceramic precursor, was mixed with polyacrylonitrile (PAN) in order to make the cyclosilazane electrospinnable. Carbon-rich PDC nanofibers were fabricated by electrospinning various ratios of PAN/cyclosilazane solutions followed by pyrolysis. Surface morphology of the electro spun nanofibers characterized by SEM show PDC nano?bers with diameters ranging from 100-300 nm. Also, thermal stability towards oxidation showed a 10% mass loss at 623°C. 2-D carbon/SiCN films were produced by drop-casting a mixture of PAN/cyclosilazane onto a glass slide followed by pyrolysis of the film. Samples ranging from 10:1 to 1:10 PAN:cyclosilazane were made by dissolving the solutes into DMF to produce solutions ranging from 1% to 12% by weight. Green, heat-stabilized, and pyrolyzed 8% films were examined with FTIR to monitor the change in chemical structure at each step of the ceramization. SEM shows that high PAN samples produced films with ceramic embedded spheroid components in a carbon matrix, while high cyclosilazane samples produced carbon embedded spheroid. Finally, this research focuses on the challenge of making fully dense, 3-D bulk PDCs materials. Here we present a composite of SiCN with reduced graphene oxide (rGO) aerogels as a route for fully dense bulk PDCs. Incorporation of the rGO aerogel matrix into the SiCN has its pros and cons. While it lowers the strength of the composite, it allows for fabrication of large bulk samples and an increase in the electrical conductivity of the PDC. The morphology, mechanical, electrical properties and thermal conductivity of graphene-SiCN composite with varying rGO aerogel loading (0.3-2.4%) is presented. The high temperature stability, high electrical conductivity and low thermal conductivity of these composites make them excellent candidates for thermoelectric applications. Generally, carbon-rich SiCN composites with improved thermal and electrical properties are of great importance to the aerospace and electronics industries due to their expected harsh operating environments.

ABSTRACT The Characterization and Analysis of In-vitro and Elevated Temperature Repassivation of Ti-6Al-4V via AFM Techniques Aaron J Guerrero Research in the corrosion of orthopaedic implants is a growing research field where implants have been known to show adverse effects in patients who have encountered the unfortunate dissolution of their implants due to corrosion. Once corrosion begins within the body, many adverse biological reactions can occur such as late on-set infections resulting in severe health complications. The focus of this research is specifically related to the problem of late on-set infections caused by localized corrosion of orthopaedic implants. In medical implants today the most common form of corrosion protection is the implant materials’ ability to impede corrosion through the formation of an oxide layer. This ability to passivate and quickly repassivate a uniform and stable oxide layer dictates how well an orthopaedic implant will survive in-vivo. To better understand the repassivation of orthopaedic implant materials, research was conducted at the nanoscale via atomic force microscopy (AFM) on anodized Ti-6Al-4V. Using an Asylum Research MFP-3DTM AFM and AFM lithography techniques, nano scratch test methods were created simulating in-vitro surface repassivation conditions. These nano-scratches were created and characterized in Hank’s balanced saline solution (HBSS) with the AFM in contact mode at 1 and 3 Hz scan rates. HBSS was used as it best simulates the pH, ionic compounds, and constituents that are commonly found in blood. It was discovered that the AFM was successful in creating in-vitro repassivation conditions. However, the ability of the AFM to successfully observe repassivation was limited by the speed of the AFM scanner. Using the same AFM scratch methods, experiments were performed in air and in-vitro and characterized with AFM conductance measurements at 20, 37, & 45 °C. The conductance measurements were taken using an AFM conductance module and allowed for observations of decreasing current measurements over time. The current data was then used to calculate current density, resistivity, conductance, and electron mobility and compared to similar experiments This study highlights the ability of the AFM to create and characterize repassivation and shows promise in developing further capability to use the AFM for characterization of repassivation on the nanoscale. Keywords: Orthopaedics, late on-set infections, repassivation, AFM, lithography, conductive measurements.

Emerging memory technologies are being intensively investigated for extending Moore\'s law in the next decade. The conductive bridge random access memory (CBRAM) is one of the most promising candidates. CBRAM shows unique nanoionics-based filamentary switching mechanism. Compared to flash memory, the advantages of CBRAM include excellent scalability, low power consumption, high OFF-/ON-state resistance ratio, good endurance, and long retention. Besides the nonvolatile memory applications, resistive switching devices implement the function of memristor which is the fourth basic electrical component. This research presents the characterization and modeling of Cu/TaOx/Pt resistive switching devices. Both Cu and oxygen vacancy nanofilaments can conduct current according to the polarity of bias voltage. The volatile resistive switching phenomenon has been observed on Cu/TaOx/delta-Cu/Pt devices and explained by a flux balancing model. The resistive devices are also connected in series and in anti-parallel manner. These circuit elements are tested for chaotic neural circuit. The quantum conduction has been observed in the I-V characteristics of devices, evidencing the metallic contact between the nanofilament and electrodes. The model of filament radial growth has been developed to explain the transient I-V relation and multilevel switching in the metallic contact regime. The electroforming/SET and RESET processes have been simulated according to the mechanism of conductive filament formation and rupture and validated by experimental results. The Joule and Thomson heating effects have also been investigated for the RESET processes. / Ph. D.