| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 93 === The first demonstration of efficient polymer light-emitting diodes (PLED) in 1990 stimulated great interest in display applications for conjugated polymers. Compared with organic light-emitting diode (OLED), PLED offer a wide variety of advantages, such as low cost and easy fabri- cation by spincoating. However, emission efficiency of the electroluminescent device needs further improvement. In order to achieve high EL efficiency, it is necessary to balance the injection rates of opposite charges and decrease the barriers of charge injection from the opposite contacts.
In this study, we prepared a series of random thiophene/maleimide copolymers and systematically investigated the influences of the thiophene content on photophysical, electrochemical, and electroluminescent properties of the resulting polymers. These copolymers exhibited good thermal stability with 5% weight loss temperature above 470℃ in nitrogen atmosphere. Optical properties of the polymers were investigated by absorption and photoluminescence spectra and electrochemical properties were studied by cyclic voltammetry. The study confirmed that the HOMO energy levels of the copolymers can be raised by increasing the thiophene content. Double layer devices ITO/PEDOT/Polymers/Al were successfully fabricated and their optoelectronic properties investigates. Incorporation of thiophene unit reduced the turn-on electric field, but decreased the luminance efficiency and the maximum brightness.
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