Syntheses and Properties of Ionic Iridium Complexes and Their Applications in Solid-State Light-Emitting Electrochemical Cells

發光電化電池（light-emitting electrochemical cell，LEC）擁有許多傳統有機發光二極體（organic light-emitting diode，OLED）沒有的優點。例如：可使用在空氣中穩定的電極（如：銀、金）和單層的元件結構，使得製程成本降低。發光電化電池的驅動電壓一般來說都很小，約等於發光分子的放光能階大小。而較低的驅動電壓有助於提高元件的壽命和電源效率。 本論文主要的研究是以離子性銥金屬錯合物或離子性有機分子為基礎，來製作低成本的發光電化電池。而設計及合成各種不同功能性的分子以符合不同元件的需求也在本論文中做了詳細的探討。在此，不同功能性的發光電化電池如白光發光電化電池、飽和深藍發光電化電池、高反應性發光電化電池及陰離子性銥金屬錯合物發光電化電池都被充分地研究並都有符合預期的效果。此外，利用歧化反應將陰陽離子性的銥金屬錯合物合成的“軟鹽”也在此討論其性質與應用。因為軟鹽屬電中性，因此在應用面是以有機發光二極體的應用來取代本論文的主軸發光電化電池。元件研究的結果顯示軟鹽內部的能階排列對於元件效率有著顯著的影響。LECs (light-emitting electrochemical cells) possess several advantages over conventional OLEDs (organic light-emitting diodes) such as compatibility with air-stable electrodes (e.g., Ag and Au) and single emissive layer which can be easily conducted from cost-effective solution process. The turn-on voltages of LEC devices are generally low and approximately equal to the measured optical band gaps of the emissive materials (close to Eg /e). The low operating voltages are beneficial for the device lifetimes and power efficiencies. In this thesis, cost-effective LEC devices based on ionic iridium complexes or ionic organic compounds have been demonstrated. The design and synthesis of various functional iridium-based complexes for the use in LEC devices including white LEC, saturated deep blue LEC, fast-response LEC, and LEC based on anionic iridium complexes were systematically performed. The results of the corresponding LEC devices are in good accordance with the expected outcome. In addition, three new Ir-based materials called “soft salt” were synthesized through metathesis reaction between halide and alkali metal salts of two cationic and three anionic iridium complexes, respectively. Since the net charge of the soft salts are zero, their use in light-emitting devices were conducted in OLED instead of LEC. The study suggests that the internal energy alignment between the two ions in the soft salts is responsible for the widely disparate results