| Electrogenerated Chemiluminescence (ECL) was generated at high frequencies using microelectrodes in order to investigate various ECL reaction mechanisms. The first part of this thesis involves using microelectrodes to examine the ECL processes for compounds used in solid-state organic display devices (organic light-emitting diodes, OLEDs). Chapter 2 describes electrochemical, spectroscopic, and electrochemiluminescent investigations of some of the most common compounds used in OLEDs. The solution-phase data is compared to the solid state and qualitative conclusions are made about the nature of the emitting species and light-producing efficiencies and mechanisms. Chapter 3 takes this study a step further using Marcus theory to probe the efficiency of the ECL cross-reactions as a function of the Gibb's free energy of reaction (Δ G). The pathways leading to light emission were established and compared to Marcus theory predictions. For most of the systems, the T-route was determined to be the dominant pathway to light emission. These results were then extrapolated to the solid state. Chapter 4 is devoted to the role of triplet states in the ECL of OLED materials. The spectroscopic, electrochemical, and electrochemiluminescent properties of two phosphorescent materials are described. A different type of ECL mechanism is considered in Chapter 5. The coreactant ECL between Ru(bpy) 3+2 and tripropylamine was studied at carbon fiber microelectrodes in order to optimize this reaction and apply it for the detection of amines. Chapter 6 takes advantage of the fact that we were able to detect individual photons with our high-speed ECL setup. Individual photons were observed for the reaction between Ru(bpy)3+2 and tripropylamine, and the stochastic nature of these individual events demonstrated. In Chapter 7, light-emitting electrochemical cells based on ECL were constructed. |
