Electrochemistry Of The Fourteen Novel Electroluminescence Materials For Organic LEDs

Since the first OLED was reported by Tang and Vanslyke in 1987, the OLED has been applied in a variety of products such as electronic and optoelectric commercial products. As we known, the electronic structure of the emitting materials is of vital importance to the characteristics of OLEDs. For example, the energy gap is defined by the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and the energy levels are required to match the work function of corresponding electrodes. The measurement of electrochemical redox properties provides a basis for estimating andassessing the electronic structure of theÏ€-conjugated molecules. However, the studies in thefield are restricted. In this thesis, we have done some work and the main results are expressed as follows:1. Uv-vis spectra and electrochemical characters of the six novel oxadiazole-based compounds were investigated in detail. The electrode reaction mechanism was reported in detail and their dynamic parameters were also calculated. In addition, the energy gap (E_g) was evaluated from the onset absorption wavelength (λ_onset /nm) of Uv-vis spectra and the energy levers of HOMO and LUMO were calculated by cyclic voltammetry(CV) and Uv-vis spectra.2. The electrochemical behaviour of two novel conjugated polymers (m-Polymer and Ph-Polymer) containing phenothiazine moieties in main chain were studied in DMF with 0.1M TBAP by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on the glassy carbon electrode (GCE). The results show that m-Polymer has a stable oxidative peak at 1.084V and a reductive peak at -1.546V due to the inserting of the group of-CN. However, PA-Polymer has two oxidative peaks at 0.852V and 1.155V and two reductive peaks at -1.682V and -2.044V respectively. By some electrochemical techniques, the electrode reaction processes were investigated in detail and their dynamic parameters were obtained. In addition, the energy levels of the frontier orbits of the two polymers were calculated using CV and UV.3. The electrochemical behaviour of another range of six novel conjugated polymers containing phenothiazine moieties in main chain was studied by electrochemical techniques in details. Their dynamic parameters were accounted using many electrochemical methods and the electrode reaction processes were deduced in detail. And the energy levels of the frontier orbits of the six polymers were calculated and analyzed. In addition, the effect characteristics of these six polymers with IIB metal ions were investigated too. The results show the addition of IIB metal ions shifts the oxidation peak potential of the corresponding phenothiazine group to more cathodal position. And it was found that the smaller shifts were obtained upon addition of Zn²⁺ and Hg²⁺ ions for those without nitrogen atoms with free electron pair such as PQ and PQDB. On the other hand, for those containing nitrogen atoms with free electron pair such as PQDN , PQTN, PQS and PQSe, the bigger shift of oxidation potentials resulted from the addition of the Zn²⁺ and Hg²⁺ ions. In addition, the value of the shift result from Zn²⁺ is larger than that of the Hg²⁺.