The work deals with the theory of preparing perovskite solar cells. How about basic structures and the specific types of training opportunities and reproducibility of results. In the third part describes the complete preparation of the article, which reached the highest efficiency and the procedure for subsequent repetition of the experiment

The tandem solar cell concept is a promising approach to improve the efficiency of photovoltaic devices. However, characterization of tandem solar cell devices is challenging since correct efficiency determination demands special experimental infrastructure as well as suitable characterization procedures. Even though the appropriate IEC and ASTM measurement standards define all that very precisely, they cannot be applied without special care to organic photovoltaics (OPV) because they were originally developed for inorganic devices. As a consequence, nowadays almost all tandem organic solar cell publications are not using correct characterization procedures, often resulting in questionable efficiency values. The aim of this work is developing a measurement procedure for tandem organic solar cells assuring their correct characterization. Therefore, at first the existing standards and measurement procedures for tandem solar cells are reviewed and challenges when applying these standards to organic solar cells are identified. As main challenges the relatively low fill factors and distinct nonlinearities of organic solar cells are identified. As preliminary experiments, single junction organic solar cells are investigated to analyze the influence of measurement parameters like bias irradiance, bias voltage, and chopper frequency on the external quantum efficiency (EQE) of organic solar cells. This results in parameter sets assuring minimized artifacts for the subsequent EQE determination of the subcells of tandem organic solar cells. The main part of this thesis presents the detailed characterization of a tandem OPV example device. First, EQE is measured and validated by two independent institutes. The EQE results are used to calculate the illumination conditions to reach AM1.5g conditions for both subcells with a multi-source sun simulator. The resulting efficiency value under standard reporting conditions (SRC) is found to be 5% lower than the efficiency measured with a single-source sun simulator. A full spectrometric characterization shows that differing fill factors of the subcells are the reason for this behavior. To overcome the main reason for the complicated measurement procedure of tandem solar cells, the inaccessibility of the individual subcells, three different approaches for the jV-characteristics determination of the subcells are presented. The so-called Bias Voltage Approach is based on EQE-measurements under varying bias voltage and needs no additional electrical contacts. Therefore, it can be applied to existing devices. The Voltage Contact Approach as well as the Current Contact Approach require in changed stack designs. Therefore, they cannot be applied to existing devices but give more accurate results. Finally, a procedure for characterizing tandem organic solar cells is formulated. This procedures aims at giving practical advice how to characterize tandem organic solar cells to achieve results conforming to the measurement standards and being as accurate and reproducible as possible. Hence, this thesis attempts to establish standards for a correct measurement of tandem organic solar cells of which other emerging solar cell technologies can profit as well.

Organic solar cells promise electricity generation at very low cost, and higher installation flexibility as compared to inorganic solar cells. The lower cost is achieved by cheaper semiconductors and easier manufacturing processes. The flexibility is naturally given by these ultra-thin, amorphous layers. Also the power conversion efficiency can be high enough for many applications. The organic molecules have to withstand the constant excitation by photons, transport of energy in form of excitons and charge. A small but significant amount of these photons has energy over the absorption gap, the excess of energy must be released without breaking the molecular bonds. In consequence, the solar cells can also heat up to temperatures at above 80°C. The objective of this work is to answer the question if the small molecules organic solar cells can be stable enough to operate under a very long time. The stability of organic doped layers in an organic solar cell is also addressed. This work starts with a general introduction followed by the description of the experimental procedures. The aging experiments of the solar cell were done with a self developed equipment. The fabrication of this equipment (a set of measurement boxes) was necessary to maintain the conditions, under which a solar cell can be aged, as constant as possible. The measurement boxes were used to control the electrical load of the cell, its temperature, the illumination intensity, and its electric connection to the IxV measurement equipment. A software package was also developed to control the equipment and to facilitate the work and visualization of the high volume of collected data. The model solar cells chosen for the aging experiments were donor-acceptor heterojunctions devices formed with the well-known materials C60 and ZnPc. Two basic different structures were analyzed, because they offered reasonable performance and potentially long lifetime: the flat heterojunction (FHJ) and the mixed heterojunction in a Metal-Insulator-p-Semiconductor (m-i-p) configuration. Variations of the FHJ and of the m-i-p structures are also used to verify the limits of the stability of electrically p- and n- doped organic semiconducting layers. The least stable solar cells are the FHJ devices. These devices show a fast initial decrease of all their characteristic conversion parameters but the Voc. After a few hundred hours, the saturation current (current under a reverse bias of 1 V) was almost stable. The saturation current is related to the number of absorbing centers, the decrease indicates that the degradation of the absorbing centers has stopped. With wavelength resolved external quantum efficiency measurements and chemical analysis, it was found that the degradation is related to the oxidation of C60. It was also shown that the use of organic dopants do not significantly affect the lifetime. The results show that the m-i-p solar cells are more stable than the FHJ devices. They are also stable under high temperatures up to 105°C. Outdoor testing also showed that the solar cells remained chemically, electrically and mechanically stable during a 900 h test.

Organische Solarzellen besitzen das Potential für leichte und zugleich flexible photovoltaische Anwendungen, die kostengünstig hergestellt werden können und damit einen Beitrag zur Verminderung der Emission von Kohlendioxid, Methan und Stickoxiden leisten können. Zur Herstellung von organischen Solarzellen werden nur geringe Mengen der organischen Materialien benötigt und die Prozessierung findet bei vergleichsweise geringen Temperaturen statt, was die Abscheidung auf z. B. Plastikfolie ermöglicht. Man unterscheidet drei Arten von organischen Solarzellen. Erstens, Solarzellen bestehend aus kleinen Molekülen, die im Vakuum durch Sublimation auf das Substrat abgeschieden werden. Zweitens, Polymersolarzellen, deren Schichten aus Lösung meist durch „spin-coating“ oder Druckverfahren präpariert werden. Und drittens, „dye-sensitized“ Solarzellen (auch Grätzel-Zellen), die aus einer porösen Schicht Titandioxid und einem flüssigen Elektrolyten für den Ladungsträgertransport bestehen. Diese Arbeit beschäftigt sich ausschließlich mit organischen Solarzellen aus kleinen Molekülen. Die höchsten erreichten Wirkungsgrade organischer Solarzellen aus kleinen Molekülen liegen derzeit bei etwa 5 % . Um die Effizienzen von Solarzellen aus kleinen Molekülen zu steigern, ist es einerseits notwendig das Verständnis der physikalischen und chemischen Prozesse innerhalb der Bauelemente genauer beschreiben zu können, andererseits werden neue Materialien mit optimierten Eigenschaften für die organische Photovoltaik benötigt. In dieser Arbeit wurden zwei Strategien zur Optimierung organischer Solarzellen verfolgt: • Durch die Optimierung des Versatzes der Energieniveaus der organischen Materialien konnte die Leerlaufspannung in einem Modellsystem maximiert werden. An diesem Modellsystem wurden der Ursprung der Leerlaufspannung und die Rekombinationsdynamik von photogenerierten Ladungsträgern untersucht. Bezüglich der Leerlaufspannung zeigen Solarzellen, deren photoaktive Materialien in einer Mischschicht vorliegen, im Vergleich zu Solarzellen, die eine photoaktive Doppelschicht beinhalten, fundamentale Unterschiede . • Des Weiteren wurden neue Thiophenderivate untersucht, die als aktive Materialien in organischen Solarzellen eingesetzt wurden. Durch elektronenziehende Endgruppen wurde das Ionisationspotential der Thiophenderivate abgesenkt und die optische Bandlücke verringert. Das Thiophenderivat DCV3T fungiert in Kombination mit herkömmlichen Donator-Materialien als Akzeptor. In Mischschichten aus DCV3T und C60 kommt es durch einen Hin- und Rücktransfer der Anregungsenergie zwischen den Materialien statt der Generation von freien Ladungsträgern zu einer Erhöhung der Triplett-Exzitonendichte auf DCV3T . Diese Exzitonen besitzen auf Grund der hohen Lebensdauer von Triplett-Exzitonen das Potential für eine erhöhte Exzitonendiffusionslänge, die in einem neuen Solarzellenkonzept ausgenutzt werden konnte . / Organic solar cells have the potential for light weight and flexible applications. They can be manufactured cost-effectively and can thus contribute to the reduction of the emission of carbon dioxide, methane and nitric oxides. In order to manufacture organic solar cells, only small amounts of organic materials are required. They can be processed at comparably low temperatures. Therefore, the fabrication on substrates like plastic foil is possible. Three different types of organic solar cells exist. The first kinds are solar cells prepared from small molecules that are manufactured via sublimation of the material in a vacuum. The second kind are polymer solar cells manufactured from solution by spin coating techniques or ink jet printing. And thirdly, dye sensitized solar cells - also known as Grätzel cells - consisting of a porous layer of titanium dioxide and most commonly a liquid electrolyte for the charge transport. This work deals exclusively with small molecule solar cells. The highest power conversion efficiencies reached by small molecule organic photovoltaics are now in the range of 5 %. In order to increase the efficiencies of solar cells prepared from small molecules, two major aspects must be developed. The understanding of the physical processes within the organic devices must be improved. And secondly, new materials are required with physical properties optimized for organic photovoltaics. In this work, I followed two strategies for optimizing organic solar cells: • By optimizing the offset of energy levels between donor and acceptor material, the open circuit voltage could be increased. In the investigated model system, the origin of the open circuit voltage and the recombination dynamics of photo generated charge carriers were analyzed. Concerning the open circuit voltage, solar cells consisting of a donor acceptor double layer structure, show fundamental differences to solar cells consisting of a donor acceptor blend. • Furthermore, new thiophene derivatives used as photoactive materials were investigated. By the attachment of electron withdrawing end groups, the ionization potential of the oligothiophenes is increased and the optical band gap is reduced at the same time. The investigated thiophene derivative DCV3T acts as an acceptor in combination with the commonly used donor-materials. A back- and forth-transfer of excitation energy is observed in blends of DCV3T and fullerene C60. In these blends, excitons are not separated into free charge carriers. This back and forth transfer leads to an enhancement of the density of triplet excitons on DCV3T. These excitons have a potentially high diffusion length due to the long lifetime of triplet excitons. This effect was utilized in the organic solar cells.

As the demand for energy increases, competition for a sustainable alternative to non-renewable energy resources has resulted in the growth of the photovoltaic industry. Although most photovoltaic technologies are based on crystalline silicon, thin film technologies have been developed with the expectation of generating a comparably high-performing product with lower processing costs. These materials have demonstrated sufficiently high optoelectronic performance to enable commercialization but concerns such as material scarcity limit terawatt level power production.<div><br></div><div>In the continuous pursuit of earth abundant solar absorber materials appropriate for thin film technologies, enargite Cu3AsS4 has been identified as a promising material due to its ideal direct band gap, stability, and high absorption. Recent efforts have demonstrated this class of copper chalcogenides exhibits band gap tunability and has solution processing capabilities for potentially scalable manufacturing. Furthermore, recent first-principles calculations of enargite Cu3AsS4 have hypothesized this material may have high carrier mobility and defect-tolerant optoelectronic properties, which further support investigation into this material. <br></div><div><br></div><div>In this dissertation, a novel reactive deposition processing route has been developed which has produced dense, single-phase enargite thin films. A champion device efficiency of 0.54% was achieved following a post deposition etching procedure on these films, which demonstrates the density and observable secondary phases were not limiting to initial nanoparticle-based device performances. Together with recent modeling efforts, the non-ideal band alignment with both the back contact and diode junction is concluded to be the primary limiting factor for high efficiency devices. <br></div><div><br></div><div>As this technology contains arsenic, concerns have been raised about its potential carcinogenicity and toxicity. Similar concerns were raised during the development of cadmium telluride technology, but these concerns have been mitigated through careful life cycle analyses and identifying strategies for responsible life cycle management. Therefore, a life cycle analysis and two risk assessments have been completed on Cu3AsS4 systems. Although emissions of arsenic and its contributions to life cycle impacts are expected to be low due to the small quantity required, hot spots have been identified to reduce waste and emissions. Reduction strategies for this material system are found to be applicable to other PV systems and include minimizing molybdenum sputter waste, reusing and recycling balance of system components, and investigating low-energy processing routes on thin substrates. This work serves to establish a basis on which the potential environmental implications of this thin film technology are understood. <br></div><div><br></div><div>This dissertation will serve as a guide toward the technical and environmental development of Cu3AsS4 thin films. Having a life cycle perspective during the systematic development of a technology will enable sustainable engineering. Furthermore, the processing and characterization methods detailed herein are expected to be generally applicable to other copper chalcogenide systems. <br></div>

The goal of this thesis is to, on behalf of JB Eco Tech, investigate a novel method of interconnecting photovoltaic (PV) modules. The principle is to stick the interconnecting strings on the cells with a transparent tape instead of soldering. As a part of the assembly process, the module is laminated under heat which makes the strings stick to the PV cell. The method is going to reduce one step in the production process, replacing the soldering procedure with the lamination of the strings onto the cells. Also, the replacement of lead and silver will spare costs and the environment. To analyse the effects of the novel method on the performance of the cell, the optical properties of the module were investigated by mathematical models and Light Beam Induced Current (LBIC). Also, the electrical properties were compared to the conventional method of soldering by analysing the I-V characteristics. The experiments were done on mini modules. Although the mini module displayed a reflectance of about 5.7 – 6.0% the contribution of the tape only accounted for a maximum of 0.5%. Since the tape only covers a fraction of the cell, this reflectance is negligible. Only 3 modules were successfully analysed, and the electrical properties of the novel method did not differ from the conventional method. To solidify the later a claim a more extensive rapport has to be made. The thesis opens up a new research area where improvements to the novel method can be done. / Det här examensarbetet är gjort på uppdrag av JB Eco Tech. De har utvecklat en ny metod i produktionen av solcells moduler. Syftet med studien är att undersöka metoden som baseras på att fästa transparant tejp med en belagd koppartråd på solcellerna istället för den konventionella metoden som använder sig av lödning. Metoden kommer att reducera ett steg i produktionskedjan genom att utesluta lödningsprocessen. Processen kommer också bidra till en minskning i användandet av silver och bly vilket bidrar till en reducerad kostnad och en minskad miljöpåverkan. För att analysera effekterna av prestandan till följd av den nya metoden så analyserades de optiska egenskaperna med hjälp av matematiska modeller och Light Beam Induced Current (LBIC). De elektriska egenskaperna hos solcells modulerna jämfördes med den konventionella metoden som involverar lödning genom att analysera I-V karakteristiken för de båda metoderna. De ovannämnda experimenten utfördes på miniatyr moduler. Resultaten som erhållits visade på att modulerna hade en reflektans av 5.7 – 6.0% och att tejpen endast stod för max 0.5%. Tejpen täcker endast en bråkdel av cellen därför går det att konstatera att reflektansen som härstammar från tejpen är försumbar. Det innebar att de optiska egenskaperna inte bidrog till en signifikant påverkan på prestandan av modulerna. De elektriska egenskaperna av modulerna påvisade ingen signifikant skillnad mellan de två olika metoderna. För att säkerställa det senare antagandet krävs en utökad studie inom området. Studien har öppnat upp för nya rön som grundas på den nya metoden där det finns utrymme för förbättringar av tejpen.

Solar cells are designed to transform the optical energy into electrical energy. Using solar energy is the best way for humans to solve the energy shortage problem. Dye sensitized solar cell(DSSC) has a low cost and helps people to obtain the solar energy expediently. The DSSC is based on nano structured TiO2 ; and dye molecules help the particles of TiO2 to absorb more photons. Hence DSSC has higher efficiency than SC(solar cell without dye). This thesis elaborates and analyzes the dye which is sensitized to TiO2. The absorption spectrum of the dye was achieved. Two kinds of dye sample were made on the basis of their places in structure of TiO2. One dye sample is solution, nanopowder of the dye in aceton. The other dye sample is film, thin film on a quartz plate. The absorption spectrums of the samples have been measured in laboratory. The measurement suggests that the dye works improves the absorption of solar energy in DSSC. This thesis mainly contains the following sections: Chapter I reviews the solar energy technology development, the research purposes, and the principles of DSSC. Chapter II introduces the theory of optical spectroscopy. Chapter III and Chapter IV describe the apparatus employed in this experimental system, the experimental method, and the testing results. Chapter V gives the conclusions drawn from the experiments.

The need to accurately measure multi-junction (MJ) tandem solar cells' subcell current-voltage characteristics is increasing due to the vital information they provide about the efficiency, stability, and longevity of the cells. These measurements are rather difficult compared to their counterpart single-layer solar cell measurements. The purpose of this project is to construct an instrument that is able to successfully bias multiple subcells in a tandem solar cell. This would allow accurate measurements of the J-V behaviours of individual subcells within the stack and by extent, allow analysis to optimise future tandem cell technology. The instrument made is a controllable multi-chromatic light-emitting diode array, consisting of six wavelength-different LEDs ranging between ultraviolet and infrared light, which the intensity of is controlled bya slider control Graphical User Interface (GUI). This instrument will bemounted on a laboratory station at the institution of solar cell technology, Ångström laboratory. Although not perfect, the instrumentcan provide sufficient background light for biasing subcells of an MJ solar cell for a wide selection of cell band gaps

In today’s society many non-renewable and environmentally harming energy sources are used to facilitate people’s everyday energy demands. This causes ecosystems to break down, global temperatures to rise, pollution and many more critical long lasting problems. By replacing non-renewable energy sources and taking advantage of the 100% renewable energy source, light, these problems will diminish. This project has been in collaboration with a company called Epishine who develop indoor organic solar cell devices to be able to replace conventual battery driven electrical devices with solar power harvested from indoor light. Since there is no good existing contacting solution, for Epishine to be able to enter the market, a contact solution between their solar cell device and the electrical devices it will power has to be developed. This thesis focuses on developing, designing, testing and evaluating the performance of new contact solutions for encapsulated flexible organic printed solar cells with the feasibility, viability, scalability and durability in focus. This project was conducted by first performing a literature study, thereafter, establishing a baseline for future referencing of new contact solutions and the main part, developing new concepts and evaluating them. By using the design thinking method, an iterative process could take place, allowing for a constant flow of new ideas whilst testing concepts throughout the project. The baseline tests were successful and the hypothesis of organic materials degrading over time was confirmed. From the many sub-concepts and production methods for a new contacting solution, two concepts showed promising results and were merged into one main concept. Two devices were created with the new concept, one functional device and one showing the design. To conclude, the thesis resulted in a functional solar cell device with a new contact solution which shows great potential and a new production method which enables all organic printed electronics to be design and developed in a more compact and component dense design. This production method is beneficial to not only Epishine, but everywhere where printed electronics are used and need to be optimized due to restrictions such as space and weight. / I dagens samhälle används många icke-förnybara energikällor för att underlätta människans vardagliga behov men skadar samtidigt miljön. Detta leder till att hela ekosystem fallerar, den globala temperaturen stiger, giftiga ämnen släpps fria och flera kritiska, långvariga problem skapas. Genom att byta ut icke-förnybara energikällor och istället dra nytta av den 100 % förnybara energikällan, ljus, kommer dessa ovanstående problem att minska. Detta projekt har varit i samarbete med ett företag vid namn Epishine som utvecklar organiska solcellsenheter för inomhusbruk, för att kunna ersätta konventionella batteridrivna elektriska apparater med solenergi tillvaratagen av inomhusbelysning. I dagsläget finns det ingen bra kontaktlösning mellan solcellsenheten och den apparat den ska driva, vilket är ett av Epishines större problem i nuläget, som hindrar dem från att kunna slå igenom på marknaden. Denna avhandling fokuserar på att utveckla, designa, testa och utvärdera prestandan av nya kontaktlösningar för inkapslade flexibla organiska solceller. Projektet började med en litteraturstudie, därefter etablerades en ”baseline” för att kunna jämföra de nya kontaktlösningarna. Största delen av rapporten handlar om att utveckla och testa nya kontaktlösningar för att sedan utvärdera dem. Genom att använda ”Design thinking” processen, kunde en iterativ process äga rum, vilket möjliggjorde ett konstant flöde med nya idéer som genererades samtidigt som koncept och prototyper utvecklades och utvärderades. Resultaten av ”baseline”-testerna var framgångsrika och hypotesen om att de konduktiva egenskaperna av organiska material försämras med tiden bekräftades. Från alla delkoncept och potentiella produktionsmetoderna för en ny kontaktlösning visade två koncept lovande resultat och slogs därför samman till ett huvudkoncept. Två olika solcellsenheter skapades med den nya kontaktlösningen implementerad. En funktionell enhet skapades och en enhet som visar layouten och designen. Sammanfattningsvis resulterade avhandlingen i en funktionell solcellsenhet med en ny kontaktlösning som visar stor potential samt en ny produktionsmetod som gör att all organisk tryckt elektronik kan designas och tillverkas i en mer kompakt och komponenttät design. Denna produktionsmetod är en fördel inte bara för Epishine utan också överallt där tryckt elektronik används och behöver optimeras i form av utrymme och vikt.

Die steigende Nachfrage nach erneuerbarer elektrischer Energie erfordert neue photovoltaische Technologien. Effiziente organische Solarzellen mit gemischten, absorbierenden organischen Molekülen wandeln Sonnenlicht in Elektrizität um und die jüngsten Rekorde des Wirkungsgrads zeigen das Potenzial für eine alternative Energieerzeugung. Trotz dieser Durchbrüche führt die Verwendung komplexer organischer Moleküle, die zu einer selbstorganisierten Absorberschicht zusammengemischt werden, zu komplizierten Morphologien, die bisher nur unzureichend abgebildet werden konnten. Die Morphologie hat jedoch einen entscheidenden Einfluss auf die Umwandlung von Photonen in Elektronen und auf den Photostrom, was sich auf die Gesamtleistung der Solarzelle auswirkt. Diese Dissertation ist eine Studie über die Morphologie organischer Dünnfilm-Mischschichten in verschiedenen organischen Solarzellen unter Verwendung analytischer Elektronenmikroskopietechniken (REM, TEM, EDX). In einem weiteren Schritt werden auch die Einflüsse der Mikrostruktureigenschaften dieser im Vakuum abgeschiedenen organischen Solarzellen auf ihre elektronischen Eigenschaften untersucht. Diese Studie umfasst bekannte Zinkphthalocyanin- (ZnPc) und Fulleren (C60) Mischschichten (ZnPc:C60) sowie neu entwickelte Materialien, DTDCTB und NGX gemischt mit C60. Auf mikroskopischer Skala wurde der Einfluss der Abscheidung der oben genannten Schichten auf unterschiedlich erhitzte Substrate, sowie deren Auswirkungen auf die elektronische Leistungsfähigkeit untersucht. Es wurden drei sehr unterschiedliche Wachstumssysteme beobachtet: • Filme mit guter Phasentrennung (ZnPc:C60) • Gut gemischte dünne Schichten (DTDCTB:C60) • Selbstorganisierende Nanodrähte (NGX:C60) Um die gewachsene Mikrostruktur zu erklären werden thermodynamische Modelle zur Erklärung der experimentellen Ergebnisse eingesetzt. Diese Arbeit bietet daher einen Rahmen, der die Planung zukünftiger Experimente leiten kann. Für die in dieser Arbeit untersuchten Schichtsysteme konnte die Korrelation zwischen den Präparationsbedingungen und der Leistungsfähigkeit der Solarzellen durch die beobachtete Mikrostruktur und die Phasenseparation von Donor und Akzeptor gut erklärt werden.:1 MOTIVATION AND INTRODUCTION 5 2 THEORETICAL FUNDAMENTALS 2.1 BASICS OF ORGANIC SOLAR CELLS 2.1.1 Organic semiconductors materials 2.1.2 Working principle of organic solar cells 2.1.3 Characteristic curves of solar cells 2.1.4 Concept of bulk heterojunction 2.1.5 Morphology and phase separation 2.2 RELEVANT LENGTH SCALES IN THE STUDY OF ORGANIC SOLAR CELLS 2.3 THE SCANNING ELECTRON MICROSCOPE 2.3.1 Introduction and working principle 2.3.2 Interaction of primary electrons with sample 2.3.3 Detecting SE and BSE electrons 2.3.4 SEM tool with FIB 2.4 THE TRANSMISSION ELECTRON MICROSCOPE 2.4.1 Working principle and components of TEM 2.4.2 Scattering in TEM 2.4.3 Operation modes in TEM 2.5 ANALYTICAL ELECTRON MICROSCOPY 2.5.1 EDX in TEM 2.5.2 EDX with high-tech detectors 2.6 CHALLENGES OF ELECTRON MICROSCOPY ON ORGANIC MATERIALS 2.6.1 Contrast formation and electron scattering 2.6.2 Damage induced by electron beam 2.6.3 Contrast formation and electron scattering 2.6.4 Necessity of low energy microscopy 3 MATERIALS AND METHODS 3.1 DONORS AND ACCEPTOR 3.1.1 The donor ZnPc 3.1.2 The donor DTDCTB 3.1.3 The donor NGX 3.1.1 The acceptor C60 3.2 FABRICATION OF ORGANIC SOLAR CELL DEVICES AND THIN FILMS 3.2.1 Vacuum deposition 3.2.2 Solar cell devices 3.2.3 Electrical Characterization 3.2.4 Organic thin films on the substrate 3.3 ELECTRON MICROSCOPES AND SAMPLE PREPARATION 3.3.1 Cross-sections using focused ion beam 3.3.2 Experimental details used in TEM/SEM 4 RESULTS AND DISCUSSIONS 4.1 ZNPC AS DONOR MATERIAL 4.1.1 Morphology of ZnPc:C60 thin films 4.1.2 Solar cell devices with ZnPc:C60 active layer 4.1.3 Conclusions and discussion 4.2 DTDCTB AS DONOR MATERIAL 4.2.1 Peculiar performance of the solar cell 4.2.2 Morphology of DTDCTB:C60 thin films 4.2.3 Solar cell devices with DTDCTB:C60 active layer 4.2.4 Conclusions and discussion 4.3 NGX AS DONOR MATERIAL 4.3.1 Morphology of NGX:C60 thin films 4.3.2 Conclusions and discussion 5 CONCLUSION AND OUTLOOK 6 APPENDIX A1 NEAREST NEIGHBOR DISTANCE A2 FROM DARK FIELD TEM IMAGES TO THE ELEMENTAL MAP A3 COMPARING THE COMPOSITION OF DARK AND BRIGHT POINTS IN THE EDX-ELEMENTAL A4 ROUGHNESS MEASUREMENTS FROM EDX IMAGES A5 SPECTROSCOPY MEASUREMENTS ON DTDCTB:C60 7 LISTS 7.1 ABBREVIATIONS 1.: Acronyms B2.: Materials B3.: Symbols 7.2 LIST OF FIGURES 7.3 LIST OF TABLES BIBLIOGRAPHY