Investigations of Charge-Transport and Photophysical Properties of Wide-Gap Organic Semiconducting Materials and Their Device Applications

Organic light emitting devices (OLEDs) have attracted wide interest for display and lighting applications in the past decade. Thus high-efficiency OLEDs with three primary color, red, green, and blue, are important for high quality display and lighting applications. Highly efficient red and green OLEDs have become readily available nowadays. However, efficient and stable blue emitters are still highly desired. Therefore the researches of wide-gap organic semiconductors for further developments are very important. mong the characteristics of organic materials, charge-transport and photophysical properties have significant effects on the device performances. In organic semiconductors, slight modification of the molecule configuration could alter the material properties significantly. Therefore, the relation between the molecule configuration and the corresponding charge-transport and photophysical properties is of high interest. n the thesis, we first investigate a series of oligofluorenes with different side-chain substituents on C9 to depict the effects of the side-chain substituents on the charge-transport properties. Subsequently, the charge-transport and photophysical properties of a series of indenofluorenes with different main-chain length are investigated. In addition, we investigate the photophysical and charge-transport properties of a series of triphenylsilyl/trityl-substituted carbazoles. The obtained information is used to explain the corresponding device performance. Further, the photophysical and charge-transport properties of a series of oligocarbazoles with different linking topologies are investigated. Ambipolar charge-transport properties are observed for the first time in some pure oligocarbazole systems. In the end, two fluorene-based materials are employed as the active layers in organic light-emitting transistors (OLETs) to demonstrate blue and color-controllable OLETs.