新穎超分子型電洞注入/傳輸材料以及其在高效率有機電激發光二極體元件的應用

Abstract

我們在傳統電洞傳輸材料PTC的側鏈上成功導入RNA-like的官能基尿嘧啶(Uracil)和腺嘌呤(Adenine)合成出PTC-U和PTC-A，利用其氫鍵作用力使高分子主鏈間產生物理性交聯，成功提升高分子的熱穩定性、電穩定性，以及使得高分子薄膜具備良好的抗溶劑腐蝕能力，有了濕式製程元件上的應用性，且因側鏈官能基的氫鍵作用力拉近高分子主鏈間距離，增加了電洞傳輸能力，此外導入官能基後使高分子的最高被佔有軌域更接近ITO玻璃的功函數，使電洞注入能力提升許多。我們也發現導入官能基的氫鍵作用力越強時，則材料表現將會越優異，像是強氫鍵作用力的PTC-A，其無論是熱穩定性、電穩定性、電洞注入能力、電洞傳輸能力都是最好的，PTC-A的Tg甚至高達192℃，利用ITO/HITMs/NPB/Alq3/LiF/Al結構做成元件以後，PTC-A的表現最佳，其外部量子效率可達2.4 %，發光效率可達8 cd/A，在元件結構為ITO/HTMs/Ir(ppy)3:PVK/BCP/Alq3/LiF/Al時，其外部量子效率可達9.5 %較PEDOT:PSS元件5.9 %高，發光效率可達36 cd/A，PEDOT:PSS元件只有21 cd/A。可見藉由RNA-like官能基導入的新型電洞注入/傳輸材料在OLED元件應用性上具備相當大的潛力。

According to the experiments, we successfully connect RNA-like group, Uracil and Adenine, on PTC, one of the traditional hole transporting materials, and then synthesize PTC-U and PTC-A. The hydrogen bond renders physical cross-link between polymer main-chains and escalates materials’ thermal stability, and electro-chemical stability. Physical cross-links make polymer film less eroded and increase the possibility of the exercise on the multi-layer of PLED devise. In addition, the hydrogen bond brought by side-chain’s functional group reduces the distance between the main-chain and increases materials’ hole transporting ability. The functional group renders HOMO energy level of polymer closer to the work function of the glass substrate of Indium Tin Oxide and improves materials’ hole injection ability. The result shows that PTC-A with strong hydrogen bond is the best on thermal stability, electro-chemical stability, the ability of hole injection, and hole transporting ability. Glass transition temperature of PTC-A is 192℃. Among the devises made by ITO/HITMs/NPB/Alq3/LiF/Al, PTC-A devise performs the best. Its external quantum efficiency achieves 2.4%, luminance efficiency is 8 cd/A. The other devise made by ITO/HTMs/Ir(ppy)3:PVK/BCP/Alq3/LiF/Al, PTC-A’s devise external quantum efficiency achieves 9.5% which is better than PEDOT’s device 5.9%. Yet, PTC-A’s devise luminance efficiency is 36 cd/A, PEDOT’s device is only 21 cd/A. Based on the experiments, the new hole injecttion/transporting materials through RNA-like group connecting show enormous potential in application use.