Electrical doping of organic semiconductors with molecular oxidants (p-type) or reductants (n-type) can greatly improve charge injection and conductivity in devices. Simple one electron reductants that are capable of reducing most electron-transport materials will inevitably also be sensitive to reaction with oxygen. Coupling electron transfer step with bond breaking/ making processes in principle can address this problem. The rhodocene dimer and related ruthenium and iridium dimeric sandwich compounds have been discussed as example of such n-dopants, reducing a variety of organic semiconductors to the corresponding radical anions, while forming monomeric cations. This class of n-dopants can be used in both vapor- and solution-processed devices, and the dopant monomer cations are large and, therefore, fairly stable with respect to diffusion. This thesis focused on increasing the utility of these and related electrical dopants. In order to reduce various electron-transport materials with lower electron affinities, which are frequently used in OLEDs, strategies and limitations to develop stronger n-dopants is discussed. Controlling the kinetics of the dopant / semiconductor reactions to allow film processing in ambient conditions, with activation of the dopants being carried out thermally or photochemically in subsequent steps is presented. An approach to covalently tether monomeric cations with themselves, surfaces or electron-transport materials is described. Electrochemical studies that further our understanding of dopant kinetics and thermodynamics is described. The dimer dopant chemistry is also compared to the corresponding hydride-reduced complexes of the cations and manganese tricarbonyl benzene dimer. The directions for future dopant design with improved properties is discussed.

Organic and inorganic/organic hybrid material development is essential for the advancement of electronic devices, such as organic light emitting diodes (OLEDs), organic thin film transistors (OTFTs) and fuel cells. These materials are superior to their inorganic counterparts due to the ability to create flexible devices that can be produced on a large scale and at relatively low cost. First, electron-transport materials (n-type semiconductors) are severely lacking for the development of sufficient OTFTs. Metal-interrupted perylene analogues have been developed, in part, to take advantage of the ability to tune the electronic properties of these complexes by simply changing the metal center. Second, fluorescent molecules play an essential role in expansion of microscale sensor systems and OLEDs. Solvent dependent triple fluorescence has been discovered for a series of isobutylnaphthalimide derivatives, which is unique for naphthalimide materials which typically demonstrate dual fluorescence. Next, oxygen reduction electrocatalysts in fuel cells have hindered commercialization due to the high price of platinum. Here, polymer-containing palladium nanoparticles utilize the metal center embedded directly in the polymer backbone to serve as a seed point for metal nanoparticle growth. The palladium nanoparticles within the polymer matrix display significant catalytic activity towards oxygen reduction. Also, poly-9,9-dioctylfluorene is at the forefront of blue-light emitting materials for OLEDs due to high quantum efficiencies and good thermal stability; however, a low-energy green band emission contaminant in devices has hindered application. Oligofluorene synthesis to understand this phenomenon can be difficult thus a boronic acid protection has been implemented before Suzuki-Miyaura coupling occurs to reduce the number of byproducts produced and to accomplish synthesis of oligofluorenes such as a pentamer and heptamer. Lastly, while deviating from organic and inorganic/organic electronic materials, a discussion on the development of a mononuclear Rh(II) complexes, specifically a piano-stool conformation which assists in isolation of this species. The piano-stool ligand structure consists of alkyl chains for easy conformational adjustments when the Rh(I) metal center undergoes oxidation, bulky phosphine groups and an electron-donating arene ring to keep the Rh(II) metal center from dimerization. Most importantly, the research conducted has strived toward advancements over a broad range of scientific investigation. / text

The organic light-emitting diode (OLED) technology is emerging to be the future technology of choice for thin, flexible and efficient display and lighting panels and is a potential competitor for the existing flat panel display technologies, like liquid crystal display (LCD) and plasma display panel (PDP). OLEDs display is already making their way from both lab and industry research to display market and the pace of development of laboratory OLED design into a commercial product is very impressive. The OLED display offers several advantages over other display technologies, such as low power consumption, easy fabrication, high brightness & resolution, light weight, compact, flexible, wide viewing angle and fast response. However, OLED display is still in amateur stage in terms of their cost and lifetime. Despite of the abovementioned advantages of OLEDs, there still several issues that need to be addressed to explore the full potential of this display technology. The development of materials with high photoluminescence quantum yield (PLQY), thermal and electrochemical stability, packaging, and light extracting technology are some of the major issues. Among the emitting materials, the achievement of robust blue emitting material with high PLQY and color purity is still a challenge due to its intrinsic wide bandgap and complex device configuration. The work presented in this thesis is devoted to the development of robust blue emitting materials based on fluoranthene derivatives. Fluoranthene unit has been chosen due to its blue emission, high photoluminescence quantum yield, thermal and electrochemical stability. The thesis is organized in six chapters, and a brief discussion on the content of individual chapters is provided below. Chapter 1 provides a short description of evolution of display technology and history of OLEDs. The generation wise development of emitting materials for white OLED is concisely illustrated. The working principle, function of individual layer and factors governing external quantum efficiency of OLED device are elaborated. Finally, the important prerequisite properties of blue emitting materials for OLED application are outlined. Chapter 2 reports the design and synthesis of symmetrically and asymmetrically functionalized fluoranthene-based materials to address the issue of PL quenching in solid state, and subsequently for application in non-doped electoluminescent devices. A detailed experimental and theoretical study has been performed to understand the effect of symmetric and asymmetric functional groups on optical, thermal and electrochemical properties. The fluoranthene derivatives reported in this chapter exibited deep blue emission with high PLQY in both solution and solid state. The vacuum deposited non- doped OLED devices were fabricated and characterized utilizing these materials as emitting layer. Chapter 3 describes the rationale design of thermally stable fluoranthene derivatives as electron transport materials for OLEDs. The two derivatives investigated in this chapter comprised of two fluoranthene units linked by diphenylsulfane and dibenzothiophene linkage. The effect of rigidity provided by ring closure in molecular structure on the physical and charge transport properties has been investigated. Such materials are urgently demanded for better performance and durability of displays. In an extension to chapter 3, fluoranthene based dual functional materials possessing blue light emission and electron transport characteristics are described in Chapter 4. The application of these materials in bilayer blue OLED device successfully demonstrated. The development of such dual functional materials is an important step to not just simplify the OLED device architecture; but also has the potential to reduce the manufacturing and processing cost significantly. Chapter 5 reports the synthesis of the star-shaped fluoranthene-triazine based blue photoluminescent materials for solution processable OLEDs. The effect of chalcogen on the photophysical and electroluminescence properties has been investigated. The main advantage of such solution processable materials over small molecules is to overcome the power consuming vacuum thermal evaporation technique for deposition. Chapter 6 describes the design and synthesis of a new blue emitting material comprising of a donor moiety and an acceptor unit to observe thermally activated delayed fluorescence (TADF). However, photophysical studies did not show any sign of delayed fluorescence in this molecule. Nevertheless, a deep blue electroluminescence is achieved using a multilayer OLED device configuration.

The history of silicon technology showed that controlled doping was a key step for the realization of e®ective, stable and reproducible devices. When the conduction type was no longer determined by impurities but could be controlled by doping, the breakthrough of classical microelectronics became possible. Unlike inorganic semiconductors, organic dyes are up to now usually prepared in a nominally undoped form. However, controlled and stable doping is desirable in many organic-based devices as well. If we succeed in shifting the Fermi level towards the transport states, this could reduce ohmic losses, ease carrier injection from contacts and increase the built-in potential of Schottky- or pn-junctions.

The history of silicon technology showed that controlled doping was a key step for the realization of e®ective, stable and reproducible devices. When the conduction type was no longer determined by impurities but could be controlled by doping, the breakthrough of classical microelectronics became possible. Unlike inorganic semiconductors, organic dyes are up to now usually prepared in a nominally undoped form. However, controlled and stable doping is desirable in many organic-based devices as well. If we succeed in shifting the Fermi level towards the transport states, this could reduce ohmic losses, ease carrier injection from contacts and increase the built-in potential of Schottky- or pn-junctions.