Satellites are evolving around the globe, expanding our possibility to explore space and many other applications. This thesis project is a model satellite used for teaching purposes in the course IE120V Electronics and Programming for Space Applications provided at KTH Royal Institute of Technology. The model can be used to teach Science, technology, engineering, and mathematics (STEM) in high school. The satellite is inspired by the MIniature Student saTellite (MIST) project carried out by the KTH Royal Institute of Technology, and hence this project will be called ”MiniMIST.” The MiniMIST aims to perform functions carried out on practical satellites. The onboard computer performs real-time image capturing, reads temperature from the surroundings, and analyzes power from solar panels and the power supply (batteries). The ground station setup is used to communicate with the satellite (MiniMIST) and receive data to be viewed and analyzed. The ESP32-Wrover was used as the main computer to run the MiniMIST. It was programmed with MicroPython and C++. Client-server communication using HTTP protocol emulated the communication between the ground station and MiniMIST with Web-Server communication. The ground station is a web page programmed using HTML, CSS, and JavaScript along with the AJAX framework. The thesis aims to build a working prototype of MiniMIST by dividing it into three sections: Hardware design, onboard computer software, and ground station software. / Satelliter utvecklas runt om i världen, vilket utökar vår möjlighet att utforska rymden och många andra applikationer. Detta examensarbete är en modellsatellit som används för undervisningsändamål i kursen IE120V Elektronik och programmering för rymdtillämpningar som ges vid Kungliga Tekniska Högskolan. Modellen kan användas för att lära ut naturvetenskap, teknik, ingenjörskap och matematik (STEM) på gymnasiet. Satelliten är inspirerad av projektet MIniature Student saTellite (MIST) som genomförts av Kungliga Tekniska Högskolan, och därför kommer detta projekt att kallas ”MiniMIST”. MiniMIST syftar till att utföra funktioner som utförs på praktiska satelliter. Datorn ombord utför bildtagning i realtid, läser av temperatur från omgivningen och analyserar ström från solpaneler och strömförsörjningen (batterier). Markstationsinställningen används för att kommunicera med satelliten (MiniMIST) och ta emot data som ska ses och analyseras. ESP32-Wrover användes som huvuddator för att köra MiniMIST. Den programmerades med MicroPython och C++. Klient-serverkommunikation med hjälp av HTTP-protokoll emulerade kommunikationen mellan markstationen och MiniMIST med webbserverkommunikation. Markstationen är en webbsida programmerad med HTML, CSS och JavaScript tillsammans med AJAX-ramverket. Avhandlingen syftar till att bygga en fungerande prototyp av MiniMIST genom att dela upp den i tre sektioner: Hårdvarudesign, inbyggd datormjukvara och markstationsmjukvara.

Philosophiae Doctor - PhD (Chemistry) / Renewable energy has become the centrepiece of research in resolving the energy crisis. One of the forms of renewable energy is solar energy. This form of energy is costly to develop. Organic molecules are promising materials for the construction of next generation photovoltaic cells considering their advantage of lower cost compared to crystalline silicon that is currently used in solar cells. This forms the basis of this research, which focused on the synthesis and characterisation of poly(3- hexylthiophene) P3HT, stannum (Sn) nanoparticles and stannum-based bimetallic stannum-titanium (SnTi), stannum-chromium (SnCr) and stannum-vanadium (SnV) nanoparticles for the application in the construction of heterojunction photovoltaic cells (PVCs).

Organic solar cells offer the possibility for lightweight, flexible, and inexpensive photovoltaic devices. This thesis studies the physics of a wide range of materials designed for use in organic solar cells. The materials investigated include conjugated polymers, conjugated dendrimers, and inorganic nanocrystals. The materials studied in this thesis fall into five categories: conjugated polymers blended with a buckminsterfullerene derivative PCBM, nanocrystals synthesised in a conjugated polymer matrix, conjugated polymers designed for intramolecular charge separation, conjugated dendrimers blended with PCBM, and nanocrystals synthesised in a matrix of conjugated small molecules or dendrimers. Conjugated polymers blended with PCBM have been extensively studied for photovoltaic applications, and hence form an ideal test bed for new experiments. In this thesis this blend was used to achieve the first pulsed electrically detected magnetic resonance experiments on organic solar cells. Nanocrystals are attractive for photovoltaics because it is possible to tune their band gap across the solar spectrum. In this thesis a one-pot synthesis is used to grow PbS and CdS nanocrystals in conjugated polymers, soluble small molecules, and dendrimers, and characterisation is performed on these composites. Previous work on dendrimer: nanocrystal composites has been limited to non-conjugated molecules, and the synthesis developed in this thesis extends this work to a conjugated oligomer and a conjugated dendrimer. This synthesis can potentially be extended to a variety of conjugated soluble small molecule: nanocrystal and dendrimer: nanocrystal systems. Conjugated dendrimers have been successfully employed in organic light emitting diodes, and in this thesis they are applied to organic solar cells. Materials based on fluorene and cyanine dye cores show excellent absorption tunability across the solar spectrum. A set of electronically asymetric polymers designed for intramolecular charge separation were investigated. Quenching of the luminescence was observed, and light induced electron paramagnetic resonance measurements revealed that photoexcitation led to approximately equal numbers of positive polarons and nitro centred radical anions. This indicates that charge separation is occurring in these molecules.

Innovative electronic device concepts that use polarization charges to provide improved performance were validated. The strength of the electric fields created by polarization charges (PCs) was suggested to act as an additional design parameter in the creation of devices using III-nitride and other highly polar materials. Results indicated that polarization induced electric fields can replace conventional doping schemes to create the charge separation region of solar cells and would allow for a decoupling of device performance from doping requirements. Additionally, a model for calculating current through polarization induced tunnel diodes was proposed. The model was found to agree well with experimental current values. Several polarization induced tunnel junction (PTJ) designs were analyzed. A novel double-barrier PTJ was conceived that would allow for the creation of a multi-junction solar cell using strained InGaN absorption layers. Future research would include the fabrication of these devices and the inclusion of thermal effects in the model for calculating current through PTJs.

Ce travail de thèse s'inscrit dans l'essor important que connaît actuellement le domaine des énergies renouvelables en terme de recherche et de nouvelles technologies de l'énergie. Il est consacré à l'étude de nouveaux matériaux hybrides "nanoparticules ZnO - cristaux liquides" en vue d'applications aux cellules solaires de type hétérojonctions en volume. La motivation est d'utiliser les propriétés d'auto-organisation et de transport de charges des cristaux liquides et d'augmenter les interfaces donneur-accepteur afin d'améliorer leurs performances. Pour la mesures des mobilités des porteurs de charge, un banc de mesure "temps de vol" entièrement automatisé a été développé. Deux cristaux liquides calamitiques ont été caractérisés (DSC, microscopie optique polarisée, UV et "temps de vol"). Deux types de transports de charge, l'un ionique, l'autre électronique sont mis en évidence pour des charges positives et négatives avec des mobilités indépendantes du champ électrique et des comportements différents en fonction de la température. Un procédé d'élaboration des matériaux hybrides a été mis au point. Les caractérisations de ces matériaux montrent l'influence de la concentration en nanoparticules (0,05 à 38% en volume). La taille des domaines dans les phases cristal liquide augmente avec la concentration alors que la température de transition isotrope-SmA diminue fortement. Un résultat important est que les phénomènes de transport sont conservés pour des concentrations importantes (jusque 12% en volume). Le transport électronique est même amélioré. Les propriétés des matériaux élaborés apparaissent intéressantes pour des applications aux cellules photovoltaïques. / This thesis work is a part of the significant growth that is currently taking place in the field of the renewable energy in terms of research and new energy technologies. It is dedicated to the study of new hybrid material "zno particles - liquid crystals" for the applications in "bulk heterojunction" solar cells. The motivation is to increase the donor-acceptor interfaces in hybrid material and to combine the self-organizing and charge transport properties of liquid crystals, in order to improve their performance. A completely automated "time of flight" measuring set-up is developed, for the measurement of the charge carriers mobility in the aforementioned hybrid material. Using the dsc, polarized optical microscopy, uv-visible spectroscopy and "time of flight", we have characterized two calamitic liquid crystals. Two types of charge transport, one ionic, and the other electronic, are highlighted for positive and negative charges with electric field independent mobility and different behaviors with temperature. A process for the elaboration of hybrid materials is developed. The characterization of these materials show the influence of nanoparticles concentrations (0,05 to 38% by volume). The size of the domains in the liquid crystal phases increases with the concentration whereas the isotropic-sma phase transition temperature decreases monotically. Under controlled dispersion of zno nanoparticles in host liquid crystal up to 12% by volume, we have conserved the transport phenomena in hybrid material and study has shown that electronic transport is improved. The characterized hybrid materials have shown their potential application in organic photovoltaic.

The manufacture of photovoltaic (PV) system components has a role to play in the industrialisation and poverty reduction strategies of developing countries. It has also been suggested that small scale local manufacture of balance of systems components has the potential to improve the maintenance, installation and use of the technology. However, PV is a complex technology and most developing countries have not been able to build the capabilities required to manufacture PV system components of an appropriate quality and price, either in the modern or small scale sectors. The factors that determine the success of PV manufacturers in developing countries are therefore of interest. Previous studies on learning in the PV industry have been focused on industry-wide concerns and have not explicitly addressed enterprise-level capability building or challenges specific to developing countries. In particular, there has been very little published about small scale PV manufacture. This thesis therefore aims to improve understanding of the factors that influence capability building, with a view to assisting decision making in relation to PV manufacture in developing countries. The aims of the study have been fulfilled by the development and assessment of a software simulation training tool for PV cell production line engineers, the development of an analysis framework, and application of it to several case study PV enterprises. Through the application of the framework to the case studies, it has been possible to assess the role of software simulations, the suitability of countries with different types of infrastructure for hosting PV manufacturing and the institutional arrangements or interventions that could be used to promote capability building for PV manufacturers in developing countries. While further case studies are required to make more than tentative conclusions, the framework developed and tested in this thesis may now be used as a tool to systematically and rapidly analyse the appropriateness of different types of PV manufacture in particular countries, to identify the weaknesses in their PV technological systems and therefore to suggest where resources should be invested and where appropriate institutional changes could be made. The simulation software has been demonstrated to be an effective capability building tool, thus providing one of the key elements required for successful manufacturing.

<p>Solar electricity is a promising energy technology for the future, and by using reflectors for concentrating solar radiation onto photovoltaic cells, the cost per produced kWh can be significantly reduced. The optical efficiency of a concentrating system determines the fraction of the incident energy that is transferred to the cells and depends on the optical properties of the system components. In this thesis, low-concentrating photovoltaic and photovoltaic-thermal systems with two-dimensional parabolic reflectors were studied and optimised, and a new biaxial model for the incidence angle dependence of the optical efficiency was proposed.</p><p>Concentration of light generally results in high cell temperatures, and the uneven irradiance distribution on cells with parabolic reflectors leads to high local currents and temperatures, which reduce fill-factor and voltage. Cooling the cells by means of water increases the voltage and makes it possible to utilize the thermal energy. The performance of a 4X concentrating photovoltaic-thermal system was evaluated. If operated at 50°C, this system would produce 250 kWh_electrical and 800 kWh_thermal per m² cell area and year. Optical performance can be increased by 20% by using better reflectors and anti-reflectance glazing.</p><p>Low-concentrating photovoltaic systems for façade-integration were studied and optimised for maximum annual electricity production. The optimisation was based on measured short-circuit currents versus solar altitude. Measurements were performed outdoors and in a solar simulator. It was found that the use of 3X parabolic reflectors increases the annual electricity production by more than 40%. High solar reflectance is crucial to system performance but by using a low-angle scattering reflector, the fill-factor and power are increased due to a more even irradiance on the modules.</p><p>Long-term system performance depends on the durability of the components. The optical properties and degradation of reflector materials were assessed using spectrophotometry, angular resolved scatterometry, Fresnel modelling, optical microscopy, and surface profilometry before and after ageing. The degradation of reflectors was found to be strongly dependent on material composition and environmental conditions. Back surface mirrors, all-metal reflectors, and polymer-metal laminates degraded in different ways, and therefore accelerated ageing must be tailored for testing of different types of reflector materials. However, new types of reflector laminates showed a potential for increasing the cost-effectiveness of low-concentrating solar energy systems.</p>

Solar electricity is a promising energy technology for the future, and by using reflectors for concentrating solar radiation onto photovoltaic cells, the cost per produced kWh can be significantly reduced. The optical efficiency of a concentrating system determines the fraction of the incident energy that is transferred to the cells and depends on the optical properties of the system components. In this thesis, low-concentrating photovoltaic and photovoltaic-thermal systems with two-dimensional parabolic reflectors were studied and optimised, and a new biaxial model for the incidence angle dependence of the optical efficiency was proposed. Concentration of light generally results in high cell temperatures, and the uneven irradiance distribution on cells with parabolic reflectors leads to high local currents and temperatures, which reduce fill-factor and voltage. Cooling the cells by means of water increases the voltage and makes it possible to utilize the thermal energy. The performance of a 4X concentrating photovoltaic-thermal system was evaluated. If operated at 50°C, this system would produce 250 kWhelectrical and 800 kWhthermal per m2 cell area and year. Optical performance can be increased by 20% by using better reflectors and anti-reflectance glazing. Low-concentrating photovoltaic systems for façade-integration were studied and optimised for maximum annual electricity production. The optimisation was based on measured short-circuit currents versus solar altitude. Measurements were performed outdoors and in a solar simulator. It was found that the use of 3X parabolic reflectors increases the annual electricity production by more than 40%. High solar reflectance is crucial to system performance but by using a low-angle scattering reflector, the fill-factor and power are increased due to a more even irradiance on the modules. Long-term system performance depends on the durability of the components. The optical properties and degradation of reflector materials were assessed using spectrophotometry, angular resolved scatterometry, Fresnel modelling, optical microscopy, and surface profilometry before and after ageing. The degradation of reflectors was found to be strongly dependent on material composition and environmental conditions. Back surface mirrors, all-metal reflectors, and polymer-metal laminates degraded in different ways, and therefore accelerated ageing must be tailored for testing of different types of reflector materials. However, new types of reflector laminates showed a potential for increasing the cost-effectiveness of low-concentrating solar energy systems.

Increased demand of power, limited fuel resources and environmental concerns have recently prompted a huge thrust on research areas of alternative energy and photovoltaics have been hailed as energy source for future. Particularly, third generation solar cell configurations like dye-sensitized solar cells and quantum dot Schottky barrier solar cells have drawn more attention because of their ease of processability, cheap cost with decent performance, low payback time and portability. Quantum dots are very attractive materials as sensitizers because of their size dependent bandgap tunability, increased oscillator strength and hence higher absorption coefficient, possibility of multiple exciton generation and photochemical robustness. Hence syntheses of quantum dot based hybrid nanostructures have received huge attention among researchers for using it quantum dot sensitized solar cell configuration. This dissertation can be divided in two parts. In the first part two different methods have been reported to prepare interconnected mesoporous nanostructures of wide band gap semiconductors like TiO2 and ZnO which is very important in providing high surface area for absorption or attachment of the sensitizers. In the second part, methods have been developed to establish direct contacts between quantum dots and wide bandgap substrates without molecular linkers which are expected to increase the electron injection rate from quantum dots to TiO2/ZnO. The entire thesis based on the results and findings obtained from the present investigation is organised as follows: Chapter-I provides a general introduction on the working principle of different type of solar cells and then gives a detailed description of the structure and electronic process of dye sensitised solar cells. Then, benefits of quantum dots as sensitizer over dye molecules has been discussed followed by the modification needed in case of quantum dot sensitized solar cells. Chapter-II deals with the materials and methods which essentially gives the information about the materials used for the synthesis and the techniques utilized to characterize the materials chosen for the investigation. Chapter-III describes a hybrid sol-gel combustion technique to synthesize large quantities of highly crystalline and phase-pure anatase powder in a single step. Titanium isopropoxide reacts with oleic acid to form a viscous liquid (oxocarboxoalkoxide) which undergoes non-hydrolytic polycondensation to form TiO2 during combustion. Oleylamine takes part in formation of reverse micelle which expands during combustion giving rise to porous interconnected membrane like microstructure of pore size ~5 nm, BET surface area of ~100 m2/g and porosity of ~ 48%. More importantly, this porous powder having a pre-existing network can be used to form thicker film by doctor blade technique from its paste and at the same time is expected to have better transport properties due to its less particulate nature. Chapter-IV presents a general method to prepare mesoporous structure from rod-like morphologies by partial sintering of a green pellet. Material having inherent anisotropy in their crystal structure tends to grow in a particular direction rather undergoing equiaxial growth. For instance, hexagonal ZnO and tetragonal rutile usually grow as rod-shaped particles. A loose compact of these nanorods give nanoporous morphology upon heating. Advantage of this method is the tunability of pore size by tuning the aspect ratio of the nanorods. Preparation of porous TiO2, ZnO and hydroxyapatite has been demonstrated from their corresponding nanorods. Chapter-V deals with a solvothermal based technique that has been developed for in-situ deposition of nanoparticles on any plane or curved surfaces conformally. This has been demonstrated for nanoparticles of FeCo, Au, Co, CdS on substrates like glass, mica, Si, NaCl, Al2O3 M-plane and also conformal coating of Au nanoparticles on polystyrene latex spheres. CdSe on rutile nanorods, ZnO nanorods and CNTs are promising hybrid nanostructures for third generation photovoltaics and their successful preparation has been detailed in the chapter. The mechanism proposed is based on dominant attractive sphere-plate interaction under high temperature and high autogeneous pressure condition which at reduced density and surface tension of the solvent reduces the dispersibility of the nanoparticle and allow effective spreading of the nanoparticles on the substrate. This method is also advantageous for coating of complicated geometry like inner walls of porous structures. Chapter-VI presents a method to coat chalcogenide nanoparticles on mesoporous TiO2 without any molecular linker which can enhance the electron injection rate from the chalcogenide quantum dots to TiO2. CdS, PbS can be easily synthesized through aqueous chemistry. For deposition of these sulfides, the ion layer gas absorption and reaction (IGLAR) method was modified to form uniform dense nanoparticles on anatase and ZnO surfaces. Nitrate salts of corresponding metal ions are dried directly on the semiconductor surface and instead of exposing it to H2S gas, it was treated with a concentrated sulfide solution. This introduces two competitive process i) dissolution of nitrate salt ii) formation of the metal sulfide. This dissolution step was absent when treated with H2S gas (IGLAR) and hence lead to a continuous coating. We have successfully produced CdS-TiO2 and PbS-TiO2 composites using this approach. Photoelectrochemical measurements on CdSTiO2 composites show an overall efficiency of 2.8% which is among the highest values obtained for this system demonstrating the applicability of the method to engineer interfaces to achieve high efficiency solar cells. Chapter-VI explores the combination of strategies of nanocrystal conversion chemistry with previously described sol-gel combustion technique to create dense and uniformly coated QD sensitized TiO2 electrode without compromising heat-treatment routines which is essential for better adhesion and to enhance performance with reduced leakage. Intimate biphasic oxide mixtures of PbO and CdO with TiO2 are first synthesized by nonhydrolytic solgel process with is followed by combustion to produce porous morphology. This powder can be coated as electrode and can sustain high temperature heat treatment routines and finally can be selectively converted to sulfides with Na2S treatment as TiO2 is immune to sulfidation under this condition. Materials at different stages are characterised by XRD, TEM, EDS, UV-Vis and XPS.

The manufacture of photovoltaic (PV) system components has a role to play in the industrialisation and poverty reduction strategies of developing countries. It has also been suggested that small scale local manufacture of balance of systems components has the potential to improve the maintenance, installation and use of the technology. However, PV is a complex technology and most developing countries have not been able to build the capabilities required to manufacture PV system components of an appropriate quality and price, either in the modern or small scale sectors. The factors that determine the success of PV manufacturers in developing countries are therefore of interest. Previous studies on learning in the PV industry have been focused on industry-wide concerns and have not explicitly addressed enterprise-level capability building or challenges specific to developing countries. In particular, there has been very little published about small scale PV manufacture. This thesis therefore aims to improve understanding of the factors that influence capability building, with a view to assisting decision making in relation to PV manufacture in developing countries. The aims of the study have been fulfilled by the development and assessment of a software simulation training tool for PV cell production line engineers, the development of an analysis framework, and application of it to several case study PV enterprises. Through the application of the framework to the case studies, it has been possible to assess the role of software simulations, the suitability of countries with different types of infrastructure for hosting PV manufacturing and the institutional arrangements or interventions that could be used to promote capability building for PV manufacturers in developing countries. While further case studies are required to make more than tentative conclusions, the framework developed and tested in this thesis may now be used as a tool to systematically and rapidly analyse the appropriateness of different types of PV manufacture in particular countries, to identify the weaknesses in their PV technological systems and therefore to suggest where resources should be invested and where appropriate institutional changes could be made. The simulation software has been demonstrated to be an effective capability building tool, thus providing one of the key elements required for successful manufacturing.