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We herein report the design and synthesis of small-donor molecules, 2,1,3-benzothiadiazole derivatives (2a–d), by Stille or Suzuki reaction. The synthesized compounds were characterized by spectroscopic and electrochemical methods. The compounds 2a–d absorb the light in a wide range (the UV-green/yellow light (2c)) and emit from green to red/near IR light (2c). Furthermore, these compounds show a narrow energy gap (1.75–2.38 eV), and high Ea values increasing for polymers, which prove their electron-donating nature and semiconductor properties. The measurements were enhanced by theoretical modeling.

Organische optoelektronische Baugruppen erreichen bislang noch nicht überall die Leistungsfähigkeit bereits etablierter anorganischer Systeme. Optimierungen der Einzelkomponenten sowie der Zusammenstellung der Baugruppen sind daher das Mittel der Wahl um die Wirksamkeit zu erhöhen. Die damit verbundenen Herausforderungen, insbesondere, dass sich die Eigenschaften einer Baugruppe nicht anhand der Eigenschaften der Einzelkomponenten vorhersagen lassen, werden in den ersten Teilen dieser Arbeit anhand der Modellsysteme der photorefraktiven Polymerkomposite und der organischen Solarzellen aufgezeigt. Ferner wird auf die Herausforderungen bei der Fertigung in herkömmlicher Atmosphäre eingegangen. Im letzten Teil der Arbeit wird anhand von Azopolymerfilmen gezeigt, dass diese sich zur Erzeugung von Oberflächenreliefs mittels strukturierter Lichtfelder eignen. Aus diesen Reliefs abgeformte PDMS-Filme erlauben die Beeinflussung der Lichtpropagation. Letztere wird mittels FDTD-Simulationen analysiert und verschiedene Strukturen bezüglich ihres Einflusses auf das Licht bewertet. To date, organic optoelectronic assemblies are not always able to achieve the performance of their inorganic counterparts. Hence, optimization of the single components as well as the compositions of the assemblies are the typical methods of choice to improve the efficiency. Challenges connected to this procedure, especially the fact that properties of an assembly cannot be derived from the properties of the single components, are demonstrated in the first parts of this thesis. Photorefractive polymer composites and organic solar cells act as model systems for this purpose. Additionally, challenges occurring during fabrication under ambient conditions are discussed. In the last part of this thesis, the fabrication of surface-relief gratings in azopolymer films via structured light fields is demonstrated. PDMS films molded from the reliefs allow for manipulation of light propagation. The effect is analyzed via FDTD simulations and multiple patterns are evaluated regarding their influence on light.

In this paper, we present a novel generalized multiparticle drift-diffusion (mp-DD) model capable to overcome some limitations imposed by the classic drift-diffusion model by taking into account multiple carrier populations. We demonstrate the model’s ability and flexibility in simulating systems from different application contexts. We conclude that the developed mp-DD model allows investigating a wide range of complex mechanisms, such as subband charge transport calculation or intersystem crossing (ISC), which are crucial for the understanding and design of organic and inorganic semiconductor devices largely employed for both photovoltaics and light emitting applications.

Transparent conductive thin films are widely used in technologies like solar cells, light-emitting diodes, and display technologies. The fabrication of transparent conductive films is currently realized with thin films of transparent conductive oxides and in particular indium tin oxide (ITO). The as-made ITO transparent conductors suffer from limitations like costly fabrication process and brittleness. The use of solution-processable nanomaterials, and especially metallic nanowires, appears as a promising alternative since it affords a large area, low-cost deposition method with high performances. This thesis aims at optimizing silver and copper nanowires synthesis and purification methods. Printing by spray coating of percolative NWs network allows manufacturing of flexible electrodes demonstrating excellent opto-electronic properties (>90 %T, Les matériaux conducteurs transparents font partie intégrante de très nombreux dispositifs optoélectroniques (de type cellule solaire, OLED, capteur tactile, etc.). Les matériaux actuellement utilisés sont essentiellement des couches minces d’oxydes métalliques et principalement d'ITO (Indium Tin Oxide). Pour des raisons techniques et économiques (évolution des marchés vers les applications flexibles), le développement de nouvelles électrodes flexibles pouvant se substituer à celles-ci est l'objet d'importantes recherches. En effet, de par sa faible résistance mécanique à la flexion et son coût d’élaboration élevé, l'ITO ne répond pas aux besoins de ces marchés émergents. L'utilisation de nanomatériaux en solution, et en particulier de nanofils métalliques, apparaît comme une alternative très prometteuse qui offre la possibilité d'utiliser des méthodes d'impression bas coût et grande surface.Ces travaux de thèse présentent les procédés de synthèse et purification de nanofils d’argent et de cuivre à forme facteur de forme. L’impression par spray de réseaux 2D percolants permet la réalisation d’électrodes flexibles démontrant d'excellentes propriétés optoélectroniques. Les nanofils d'Ag semblent toutefois être de meilleurs candidats que les nanofils de Cu (synthèse multi-grammes, impression grande surface, meilleure stabilité à l'air, etc.). Ainsi, après avoir identifié les principaux verrous technologiques ayant trait à l'utilisation des Ag NF (rugosité, adhésion, travail de sortie, stabilités environnementales/électriques), différentes solutions ont été proposées dans le but d’améliorer les performances et de rendre les nanofils d'argent compatibles avec l'intégration en dispositif.Le potentiel des nanofils d'argent en tant que remplaçants de l'ITO a été confirmé grâce à l'intégration réussie d'électrodes dans divers dispositifs fonctionnels (cellule solaire organique, capteur tactile capacitif ou encore film chauffant).

We have developed a room-temperature solution processing approach to integrate colloidal anatase titanium dioxide nanorods (TiO2 NRs) and lead sulfide quantum dots (PbS QDs) into a heterostructured p-n junction device. To this aim we have exploited a post-deposition treatment to remove surface-adsorbed ligands by means of UV-light-irradiation of TiO2 NRs and a dilute acid treatment of PbS QDs. Here we report a systematic study on the optimization of the post-deposition treatments and device fabrication. Our approach is fully compatible with plastic device technology and is potentially useful for the integration of crystalline TiO2 as active component into disparate solar cell architectures and organic optoelectronic devices. © 2013 Elsevier B.V. All rights reserved.

A new ruthenium sensitizer based on a heteroaromatic-4,4'-π-conjugated 2,2'-bipyridine, bearing conjugated it-excessive heteroaromatic rings as donors is presented. Dye-sensitized solar cells have been fabricated based on the novel ruthenium complex [Ru(II)LL'(NCS) 2 ] (L = 4,4'-bis[(E)-2-(3,4-ethylenedioxythien-2-yl)vinyl]-2,2'-bipyridine, L' = 4,4'-(dicarboxylic acid)-2,2'-bipyridine) and their photoelectrochemical properties have been measured under various conditions. Using this sensitizer photovoltaic efficiencies up to 9.1 % under standard global AM 1.5 sunlight were obtained. DFT/TDDFT calculations have been performed for the sensitizer in solution. By calculating the excited states energy and character and comparing the results with the conduction band edge of a model TiO 2 nanoparticle, we were able to highlight the factors affecting the measured photovoltaic efficiencies.