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Idag är människor i behov av Wi-Fi, eluttag samt belysning och samtidigt är kollektivtrafiken en stor del av människors vardag. Syftet med arbetet är att undersöka huruvida en implementering av solceller kan gynna samhället utifrån ekonomiska, ekologiska och sociala perspektiv. Studien beskriver även hur prisskillnaden mellan On-Grid och Off-Grid kan variera på grund av komponenter som används i implementeringen. I genomförandet undersöks energibehovet för Wi–Fi, LED-belysning och eluttag och detta har lett till att batteristorleken för systemet är 150 Ah. Däremot har Sverige få soldagar vilket leder till att antal mörka nätter approximeras till två och batteristorleken fördubblas därför till 300 Ah. Resultatet uppvisar att anslutande av elnät till busshållplatsen betingar ett pris av 100 000 kr men att implementera Off-Grid system på busshållplatsen kostar 23 653 kr för huvudkomponenter exklusive pris av montering, säkring och kablar. Genom att implementera solceller på On-Grid systemet kan elkostnader för bolaget minskas och återbetalningstiden förkortas. Studien kom fram till att två paneler av Midsummer BOLD med 195 Wp kommer täcka systemets behov. Dessa paneler är svensk tillverkad från 100% förnyelsebar el och har lågt koldioxidutsläpp med runt 90% lägre än traditionella solceller. / Today, people need Wi-Fi, electrical outlets, and lighting, and at the same time public transport is a large part of people's everyday lives. The purpose of the work is to investigate whether the implementation of solar cells can benefit society from an economic, ecological, and social perspective. The study also describes how the price difference between On-Grid and Off-Grid can vary due to components used in the implementation. The implementation examines the energy needs for Wi-Fi, LED lighting and electrical outlets and this has led to the battery size for the system being 150 Ah. On the other hand, Sweden has few sunny days, which leads to the number of dark nights being approximated to two and the battery size therefore doubling to 300 Ah. The results show that connection of the electricity network to the bus stop requires a price of SEK 100,000, but implementing Off-Grid systems at the bus stop costs SEK 23,653 for main components excluding the price of assembly, fuse, and cables. By implementing solar cells on the On-Grid system, electricity costs for the company can be reduced and the repayment period shortened. The study concluded that two panels of Midsummer BOLD with 195 Wp will cover the system's needs. These panels are Swedish made from 100% renewable electricity and have low carbon dioxide emissions with around 90% lower than traditional solar cells.

<p>An ammonium polysulfide (NH₄)₂S_x solution was optimized through a series of experiments to be used for surface passivation of III-V nanowires . The effectiveness of sulfur passivation was investigated by measuring the photoluminescence from p-InP nanowires before and after passivation. The optimized parameters included solvent type, molarity and passivation time. According to the experiments, passivation of nanowires in 0.5 M solution diluted in isopropyl alcohol for 5 min produced the maximum photoluminescence improvement. It was also demonstrated that the whole surface passivation of vertical nanowires in ensemble samples caused a 40 times increase in the photoluminescence intensity while top surface passivation of individual nanowires resulted in a 20 times increase of photoluminescence intensity. A model was developed to calculate the photoluminescence from single nanowires under different surface recombination and surface potential. The model showed that the 40 times increase in the photoluminescence is mainly due to the reduction of surface state density from 10¹² cm^-2before passivation to 5×10¹⁰ cm^-2after passivation.</p> <p>The effect of sulfur passivation on core-shell p-n junction GaAs nanowire solar cells has been investigated. The relative cell efficiency increased by 19% after passivation.</p> / Doctor of Philosophy (PhD)

To improve the performance of solar energy converters and its implementation as a more sustainable electricity source worldwide, researchers have been trying to increase the efficiency of photovoltaic devices while lowering their costs. Conversion efficiency of solar cells can be enhanced through light trapping structures and concentration of incoming light. Light trapping is usually realized by texturization of the solar cell’s surfaces, while concentration is achieved by addition of external apparatus, such as reflectors. A novel design for silicon solar cells is proposed in this thesis, which contains hemispherical dish microconcentrators for light trapping purposes. Through a process flow that includes maskless photolithography, thermal reflow, and metallization via sputtering, the microconcentrators were fabricated and demonstrated to have good concentration properties. Further studies need to be done for optimization of the hemispherical structures, as well as successfully perform the proposed upconverting photolithography for auto-aligned exposure of the photoresist at the microconcentrator’s focus, thus allowing a complete solar cell to be created based on this design. / Thesis / Master of Applied Science (MASc)

Yes / Organic photovoltaics (OPVs) die due to their interactions with environmental gases, i.e., moisture and oxygen, the latter being the most dangerous, especially under illumination, due to the fact that most of the active layers used in OPVs are extremely sensitive to oxygen. In this work we demonstrate solution-based effective barrier coatings based on composite of poly(vinyl butyral) (PVB)and mica flakes for the protection of poly (3-hexylthiophene) (P3HT)-based organic solar cells (OSCs)against photobleaching under illumination conditions. In the first step we developed a protective layer with cost effective and environmentally friendly methods and optimized its properties in terms of transparency, barrier improvement factor, and bendability. The developed protective layer maintained a high transparency in the visible region and improved oxygen and moisture barrier quality by the factor of ~7. The resultant protective layers showed ultra-flexibility, as no significant degradation in protective characteristics were observed after 10 K bending cycles. In the second step, a PVB/mica composite layer was applied on top of the P3HT film and subjected to photo-degradation. The P3HT films coated with PVB/mica composite showed improved stability under constant light irradiation and exhibited a loss of <20% of the initial optical density over the period of 150 h. Finally, optimized barrier layers were used as encapsulation for organic solar cell (OSC) devices. The lifetime results confirmed that the stability of the OSCs was extended from few hours to over 240 h in a sun test (65◦C, ambient RH%) which corresponds to an enhanced lifetime by a factor of 9 compared to devices encapsulated with pristine PVB. / Higher Education Commission of Pakistan through NED University of Engineering and Technology, Karachi, Pakistan and “The APC was funded by Deanship of Scientific Research, King Saud University for funding through Vice Deanship of Scientific Research Chairs”.

Since their discovery, fullerenes and metallofullerenes have been investigated regarding their structures, synthesis, isolations, and applications. The highly symmetric structures of fullerenes and metallofullerenes lead to extraordinary physical properties, such as electron transfers, and attract major attention from the science community. It has been well established that the stabilities of fullerenes and metallofullerenes can be estimated by recognizing structural patterns. Recently, we developed a generalized spiral program and additional codes and believe they are useful for fullerene/metallofullerene researchers. The higher fullerenes, those with more than 90 carbon atoms, also follow certain structural patterns. In our studies, we have shown that the higher fullerenes with tubular structures are stable in thermodynamics and can survive the aminopropanol reaction, but other spherical fullerenes cannot. For the past three decades, great efforts have been devoted to applying fullerenes and metallofullerenes as electronic materials. In our studies, we find the ground state electron transfer properties endow metallofullerenes as an ideal material for perovskite solar cells to enhance the stabilities. It has been shown in our investigations that common metallofullerenes, such as Sc3N@C80, are capable to be as the electron transfer layers in perovskite solar cells, and the test demonstrates that our novel perovskite solar cells may achieve high stability and high efficiency. The electron transfer abilities of metallofullerenes are studied with the M2@C79N since electron densities located in between the two metal atoms convert between a single electron bond and a double electron bond. The huge spherical electron delocalized structures of fullerenes and metallofullerenes lead to strong interactions with other delocalized systems, such as graphene. Previous studies have shown that graphene has a unique ability in molecular adsorptions. However, the graphene surface is not always flat and the rippled areas have effects on the packing styles. Therefore, we examined the behavior of fullerenes on the rippled graphene surface and then compared with another flat molecule, PTCDA. The results show that the effect of rippled areas varies due to molecular structures. This study gives instructions for electronic device manufacturing using graphene and fullerenes. In our studies, polarizability is a key factor of fullerenes and metallofullerenes. It has been shown that the chromatographic retention behavior has a strong relationship with the average polarizability of a molecule. Based on the experimental data, we built a model for the prediction of chromatographic retention times using computational polarizabilities. After that, we validated the model by two series of chromatographic data. The characterization of carbon-based materials has been long investigated. In the last chapter, we introduce a dynamic nuclear polarization-based method to characterize the structures of chars and studied the adsorption of oxygen on the activated radical sites. Overall, the dissertation reports my Ph. D. studies in the areas including theoretical studies of fullerene geometries, chromatographic models, applications and also experimental studies of the applications of fullerenes/metallofullerenes and characterization. / Doctor of Philosophy / Fullerenes and metallofullerenes are important materials for engineering and science. In general, a fullerene cage contains only carbon atoms and has a closed spherical structure. Theoretically, for a given number of carbon atoms, there are thousands of different ways to assemble a fullerene structure, just like assembling Lego. However, just a limited number of fullerene molecules have been discovered. In the past four decades, several theories have been proposed to explain the fact. For example, an isolated pentagon rule shows that the fullerene structures should not have any conjugated pentagons, which will decrease the stabilities of fullerene molecules. In this dissertation, I would like to show our results, which demonstrate fullerenes that can be synthesized follow certain patterns. We apply experimental and theoretical methods to discover the patterns and explain the reason. The application of fullerenes/metallofullerenes is another hot topic. We consider the structures of fullerenes endow them extraordinary abilities of electron transfers. Therefore, we use metallofullerenes as electron transfer material in a solar cell, and we have a good solar cell with high efficiency. We also inspect the interactions between fullerenes and rippled graphene surface. The results are also extended to understand the chromatographic behavior of fullerenes. By considering the physical properties of fullerenes, we build up simple models to simulate the chromatographic retention behaviors of fullerene inside the chromatographic column. The characterization of carbon-based material is a big challenge and in this dissertation, we demonstrate our contributions of a novel method for characterization, which can detect activated carbons.

<p dir="ltr">This research presents a comprehensive study of a 3D Perovskite Solar Cell model using Finite Element Analysis (FEA) and Machine Learning (ML). The research aims (i) to understand how material properties impact solar cell’s performance by applying basic semiconductor physics principles (ii) to investigate how interfacial delamination affects the performance of Perovskite solar cells (iii) to determine the optimum thickness of different layers of the solar cell (iv) to determine the fatigue life cycle of Perovskite layer.</p>

Mesoporous semiconductors such as TiO2 nanoparticles, as well as transparent conducting oxides (TCOs) such as indium tin oxide films are typically employed for setting up the photo-electrode module in variety of photoelectrochemical cells including Dye-Sensitized Solar Cells (DSSCs). In order to exhibit a high performance efficiency, the photo-electrodes in such applications are required to be able to harvest the light and transport the generated electrons effectively. Accordingly mesoporous layers with high values of surface area and well-established pore structure along with highly transparent and conductive TCOs are deposited on suitable substrates through the physical or chemical vapor deposition methods. The processing facilities and materials required to fabricate such high-quality devices with high values of efficiency are complicated and expensive, whereas devices of lower quality do not fulfill the demands. This issue is of particular importance regarding the energy production and developing the solar cell technologies, as it is considered by the concept of “cost per watt”. Thus, a great deal of effort is being carried out globally to enhance the efficiency of affordably-produced solar cells such as low-cost DSSCs. Utilizing the wet chemical techniques such as sol-gel method which provide a considerably more affordable route to synthesize nanoparticles and deposit thin films without the need of applying high temperature or vacuum condition is a widely-used approach to decrease the processing expenses. However, to achieve an acceptable cost-per-watt ratio requires enhancing the obtained efficiency value as well, and therefore, modifying the processing procedures to improve the required features of the products are highly encouraged. This thesis focuses on two individual activities: synthesis of TiO2 nanoparticles, and also thin film deposition of a promising TCO called aluminum-doped zinc oxide (AZO); both obtained through the sol-gel route that is modified to contribute to nanostructures with suitable features for application in photoelectrochemical devices such as DSSC. In the first part, mesoporous anatase nanoparticles were synthesized through the surfactant-mediated sol–gel route. Through changing the refluxing time and water-to-surfactant molar ratio, as-prepared nanocrystals of high density and large and narrowly-distributed pore sizes were obtained, displaying surface area values up to 240 m2·g-1, much higher than the reported values for commercial TiO2-based catalysts. In the second part, sol–gel dip–coating of ZnO thin films doped with 2 at.% of aluminium ions was carried out. By altering the hydrolysis reaction and changing the thermal treatment procedure, thin films of highly c-axis preferred orientation were obtained with optical transmittance of around 80% and resistivity values down to 6 – 15 mΩ·cm, corresponding to sheet resistance of around Rsh ~ 500 Ω/sq. The obtained conductivity values, even though one order magnitude lower than those reported for the AZO thin film prepared via expensive techniques, are in the suitable range to improve the cost per watt ratio in applications such as inkjet printing of low-cost printed electronics and more affordable DSSC devices.