A study of poly(3,4-ethylenedioxythiophene) (PEDOT) and related device applications is presented in this work. Some of the fundamental properties and applications of organic electronic materials are introduced in Chapter 1, while organic light-emitting diodes (OLEDs) are discussed in greater detail in Chapter 2. A brief review of previous work on conductivity enhancement in PEDOT films is presented in Chapter 3. In Chapter 4, the final introductory chapter, some of the key organic materials and experimental techniques used in this work are described. Chapter 5 details optoelectronic characterization of F8T2Ipolyfluorene blends for OLED application. Development of deep-blue light-emitting dendrimers for electroluminescence and optical gain applications is detailed in Chapter 6. The focus of Chapter 7 is on the effects of secondary doping poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) with a series of short-chain glycols. FinaJly, in Chapter 8, the synthesis, morphology and optoelectronic properties of highly conductive PEOOT films prepared by vapour phase polymerization (VPP) are reported. The emphasis of the final two chapters is on the development of VPP PEOOT and secondary doped PEOOT-PSS as suitable organic alternatives to ITO anodes in OLEOs and other organic electronic devices.