新穎超分子電洞傳輸材料應用在有機發光二極體之研究

Abstract

本研究將超分子基團尿嘧啶（uracil，U）導入高分子poly(3 -hexylthiophene)（P3HT）中，並成功以格林納反應合成出高規則度的PUC6T-click系統，以氯化鐵反應合成出較低規則度的PUC6T-FeCl3、P3HT-U 3:1系統，提升電洞傳輸材料P3HT之抗蝕性、熱穩定性及光電性質，使其光學性質與物理性質能夠在應用上有正面的改進。藉由FT-IR可以清楚觀測到氫鍵作用力的生成，利用1H NMR spectroscopic titration求得在d-CDCl3溶劑下Ka值為28.6 M-1。熱性質方面，當 U 導入側鏈後會因π-π堆疊的破壞而降低Td、Tg，同時也使得最大UV-vis、螢光放光光譜的峰值皆往藍位移。此外，本研究所合成出來的PUC6T系統能有效抵抗甲苯及氯苯等PLED製程常用的溶劑，不會因為接下來的濕式製程而影響到電洞傳輸層的完整性，說明了我們的材料具有運用在PLED元件上的潛力。我們所合成的材料作為電洞傳輸層製成兩層的發光二極體，其結構為 ITO/HTL/Alq3/LiF-Al ，此元件的各項效率皆隨著高分子中 U 的含量增加而增加，PUC6T-FeCl3之EQE可達0.363 比P3HT-commercial的0.041高出近十倍。在導入 U 後亦可提升材料的能階，使LUMO高於發光層材料，使得本研究所合成之材料不僅可以做為電洞傳輸層，同時亦有電子阻擋的作用。

A new concept to modify and enhance properties of existed functional polymers through bio-complementary interaction has been exploited. In this thesis, new DNA-mimetic π-conjugated poly(3-thiophene)s (P3HT) have been prepared which exhibits high thermal stability, non-corrosion, excellent hole injection and electron-blocking abilities in the solid state owing to the uracil induced physical cross-linking. The self-complementary phenomena were investigated by 1H NMR titration, DSC, WAXD and AFM in cast film provided further details into the nature of the self-assembly of these systems. Moreover, electrochemical studies reveal that the energy level of the highest occupied molecular orbital (HOMO) for these materials is between -5.12 and -5.17 eV, which is a good match for the work function of indium tin oxide (ITO), a commonly used anode for organic and polymer light-emmitting diodes (OLED and PLED). When the uracil-containing P3HTs are utilized as a hole-transporting layer (HTL) in the double layers OLED device, we found that the performance of the resulting device can be “ten times” higher than the high regularity and low regularity P3HTs and the performances are comparable to devices composed of the conventional PEDOT-PSS as HTLs with relatively less corrosive. This newly developed material may provide a potential route towards next-generation high-efficiency LED devices.