- 學位論文
旋環雙芴衍生物與濕式製程有機發光二極體材料之開發探究及其光電應用
Development and Optoelectronic Applications of Spirobifluorene-Based Materials and Solution-Processable OLEDs Materials
摘要
1. 以旋環雙芴為主體材料之光電應用 以旋環雙芴為主體的寡聚合物或高分子材料，近年來常被應用於有機光電材料之研究中。本論文裡我們在其2,2'的位置引入左右不對稱之取代基團，此兩相正交相互獨立的共軛鏈，除可避免分子堆疊外，更使欲設計之分子具光學異構物之特質。首先，我們將帶有二羫基之旋環雙芴與拆旋試劑作用，可分離出左旋之(S)-BrSOH及右旋之(R)-BrSOH，最後再引入發光基團pyrene，即可合成出具有旋極化放光之發光材料 (glum ~ 0.001)。此外，在此正交之旋環雙芴核心架構下，我們引入推拉電子基團，使兩兩錨定基團之距離為10.05 A，讓其能夠以類似N719 的雙牙基形式緊緊吸附於TiO2上，提高吸附率，進而達到高效率之染料光敏化太陽能電池 (3.75%)。最後，我們更將左右不對稱之推拉旋環雙芴衍生物 (CN1) 吸附在金的電極表面進行電聚合反應，藉由調控電化學沉積之週期來修飾金電極表面之功函數。 2. 濕式製程有機發光二極體材料之開發探究 相較於真空沉積技術，濕式製程具有製備簡單及成本低廉的特性，可望成為下一代OLEDs面板的主流。因此，本論文構想即針對如何克服薄膜材料對塗佈或噴印溶劑的穩定性問題加以探討，並進一步瞭解其複雜的介面關係。其中我們所開發之新型交聯式材料及離子性電子傳輸材料便可有效克服溶劑侵蝕或混合到前一層薄膜材料之問題。首先，我們合成出一系列熱聚型電洞注入材料、電洞傳輸材料、發光材料及電子傳輸材料。此類材料塗佈於基板後，可經由交聯聚合反應以達到抗溶劑侵蝕的效果。其中，熱聚型電洞傳輸材料具有相當高的穩定度及載子傳導特性 (大約 10-4 cm2 V-1 s-1)。原子力顯微鏡則進一步提供我們熱聚分子薄膜形貌的資訊，對於我們在聚合材料評估、開發及元件應用可做完整且有系統的研究。最後，離子性電子傳輸材料可藉由溶劑極性之不同，成功塗佈並製備多層式OLED元件。我們更針對其側鏈取代離子之不同，量測其電荷傳導特性及元件表現。另外，退火對於離子性共軛高分子之影響，可藉由Hofmann elimination來解釋側鏈離子之脫附。其操作機制可以由電子傳輸層之厚度及離子密度來加以調控。
並列摘要
1. Spirobifluorene-Based Materials for Optoelectronic Applications Recently, molecules possessing a 9,9'-spirobifluorene core are used widely in organic optoelectronics. In this dissertation, different functional groups were introduced to form 2,2'-A,7,7'-B-substituted spirobifluorene (left-right asymmetric). The bridging of two chromophores perpendicularly via a sp3-hybridized atom into a spiro configuration hinders the aggregation between molecules. In addition, optically active enantiomer is possible to obtain in the left-right asymmetric system. First, (S)-BrSOH and (R)-BrSOH were resolved by clathrate formation between racemic dissymmetric 2,2'-dihydroxy-7,7'-dibromo-9,9'-spirobifluorene and the resolving reagent. New enantiomerically pure spiro compounds bearing pyrene moieties were synthesized and capable of preferentially absorbing and emitting circularly polarized light (glum ~ 0.001). Second, a new dye (SSD1) featuring two donor/acceptor chromophores aligned in a spiro configuration with two anchoring groups separated at a distance of 10.05 A (closely matching the distance between the adsorption sites of the anatase TiO2 surface) undergoes efficient dye adherence on TiO2 films. A dye-sensitized solar cell incorporating SSD1 exhibited a power conversion efficiency of 3.75%. Third, spirobifluorene-based donor (triphenylamine)–acceptor (cyano) bipolar systems has been investigated. Organic films (CN1) were formed on gold electrode by electrochemical polymerization. The gold surface work function can be changed over more than 0.4 eV depending on the numbers of electrochemical deposition cycles. 2. Development of All Solution-Processed Multilayer Organic Light-Emitting Diodes (OLEDs) Compared to vacuum deposition technique, solution-based deposition is more attractive for next generation OLEDs because of the simple process and low instrumental cost. The overall theme of this dissertation is to overcome the difficulty in achieving purely all-solution processing multiple-layer OLEDs and understanding the resulting complex interfaces. In order to alleviate the interfacial mixing problem, two promising approaches are investigated here. The first approach is the use of an organic-soluble precursor that becomes insoluble through crosslinkable reactions. With such a concept, thermally crosslinkable hole injection materials (HIMs) and/or hole transport materials (HTMs), emitting materials (EMs), and electron transport materials (ETMs) were designed and synthesized. These crosslinked HTMs, studied using time-of-flight techniques, exhibited remarkable stability and non-dispersive hole transport properties, with values of