配位基不全同之羥基萘啶鉑錯合物作為磷光摻混物應用在磷光螢光混成白光有機發光二極體

Study of heteroleptic platinum complexes based on hydroxynapthyridine derivatives as phosphorescence dopants for hybrid white OLED applications

亞努納(Anurach Poloek)

指導教授 ： 陳昭岑

共同指導教授 ： 陳錦地(Chin-Ti Chen)

國立臺灣大學/理學院/化學研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.01223

摘要

摘要

鉑錯合物(platinum complexes)應用於有機發光二極體(OLED)在近年引起越來越多的關注，因為它擁有特別的電、磁及光學性質。此外，鉑錯合物之正方形平面幾何結構在高濃度溶液或固態下，分子與分子之間距離較近，容易聚集堆疊及產生激發二聚體(excimer)使得放光較單一分子紅位移且半波寬更寬。因此，鉑錯合物已經成為單摻雜磷光白光有機發光二極體或高光色純度混摻白光有機發光二極體的熱門摻入材料選擇。
在本論文中，成功合成一系列新的雜配位基鉑錯合物(FPtXND)。將4-羥基-1,5-萘啶衍生物(4-hydroxy-1,5-naphthyridine derivatives, XND)當做一個配位基再和2-（2,4-二氟苯基）吡啶(2-(2,4-difluorophenyl)pyridine, F)配位基進行合成，4-羥基-1,5-萘啶衍生物之取代基包含甲基(X = m)、二甲基(X = mm)、苯氧基(X = OPh)、哌啶(X = pp)、咔唑(X = Cz)、苯基(X = Ph)、二甲胺(X = dma)，嗎啉(X = mor)和吩嗪(X = pxz)。所有材料都逐一進行化學結構鑑定、材料物理性質量測以及將其製作成有機發光二極體元件並量測其元件效率。
在二氯甲烷及甲醇混合溶液中成功得到FPtOPhND、FPtCzND、FPtdmaND和FPtpxzND晶體並通過單晶X-射線衍射晶體學進行結構鑑定。因兩個配位基上之氮原子呈現反式結構(trans conformation)使得四個鉑錯合物分子結構為一個扭曲的正方形。且可觀察到四個鉑錯合物在分子間堆積模式並不相同，進而影響到光激發光（photoluminescence）和電激發光（electroluminescence）之光色。在高濃度溶液及摻雜的薄膜情況下因同時擁有單體分子、堆疊分子及激發二聚體的放光使這類鉑錯合物都具有較寬且較紅位移的放光。
將鉑錯合物作為摻入材料應用於有機發光二極體，利用蒸空熱沉積法(vacuum-thermal-deposition process)進行元件製作。在單色有機發光二極體元件測試中，將鉑錯合物(FPtXND)摻雜在4,4'-二（9H-咔唑-9-基）-1,1'-聯苯（CBP）中顯示出黃綠、橙黃或桔紅色電激放光。鉑錯合物摻入在主體材料中被有效的分散開來，所以可以非常明顯的看到不同取代基與光色改變之間的關聯性。此外我們成功的製作出單一發光層結構之混摻式白光有機發光二極體，利用高亮度藍色螢光材料4P-NPD作為FPtmND、FPtmmND、FPtOPhND、FPtppND、FPtCzND，FPtdmaND和FptmorND摻入物之主體材料。為改善白光有機發光二極體的性能，我們拿FPtmND，FPtOPhND，FPtdmaND和FptmorND進行分別混摻入CBP及4P-NPD中製作雙層發光層白光有機發光二極體進行測試。FPtOPhND表現出最好的純白色的電激發光光色具有的CIEx,y（0.33，0.31）和演色度(CRI)高達91。此外，FPtOPhND的電激發光在7及10伏特不同驅動電壓下CIEx,y和演色度都只有些微的變化，更達到最高電激發光效率11.8％、25.9 cd A-1或11.6 lm W-1。

關鍵字

鉑錯合物 ； 混摻式白光有機發光二極體 ； 電激發光 ； 光激發光 ； 單體分子 ； 激發二聚體

並列摘要

Abstract
Platinum complexes have drawn increasing attention for use in organic light-emitting diode (OLED) applications because of their unusual electrical, magnetic and optical properties. In addition, square planar molecular geometry of platinum complex easily promotes molecular aggregation and excimer formation in a concentrated solution or solid state through either a close packing of adjacent molecules or a short metal-metal (Pt-Pt) distance which often displays red shifted or broadened emission different from its isolated molecule. Thus, platinum complexes have become a popular choice for all phosphorescence single-dopant white OLEDs or high quality hybrid white OLEDs. In this thesis, a new series of heteroleptic platinum complexes (FPtXND) bearing 4-hydroxy-1,5-naphthyridine derivatives functionalized with methyl (X = m), dimethyl (X = mm), phenoxy (X = OPh), piperidine (X = pp), carbazole (X = Cz), phenyl (X = Ph), dimethylamine (X = dma), morpholine (X = mor) or phenoxazine (X = pxz) unit as one ligand and 2-(2,4-difluorophenyl)pyridine as the other common ligand (F) were newly synthesized and characterized as well as the detailed correlations of chemical structures with material properties and device performances were also demonstrated. The crystal structures of FPtOPhND, FPtCzND, FPtdmaND and FPtpxzND were successfully grown from dichloromethane/methanol solution and were determined by the single-crystal X-ray diffraction crystallography. The molecular structure of four platinum complexes exhibits a distorted square planar geometry with the two coordinating nitrogen atoms in trans conformation. However, different molecular packing pattern can be observed for all four platinum complexes, which affects the photoluminescence (PL) and electroluminescence (EL). Due to the contribution from both monomers and excimer/aggregate, all FPtXND exhibited broad and red-shifted PL in concentrated solution as well as in doped thin film. For OLED applications, these platinum complexes were used as dopants and the devices were fabricated by vacuum-thermal-deposition process. In monochromatic OLED testing, FPtXND doped in 4,4'-di(9H-carbazol-9-yl)-1,1'-biphenyl (CBP) exhibited greenish yellow, orange yellow or orange red EL. The EL colors of isolated molecule were well correlated with substituent effect. Furthermore, hybrid white OLEDs were first acquired with single emitting layer configuration, of which highly fluorescent blue N,N′-di-1-naphthalenyl-N,N′-diphenyl-[1,1′:4′,1〃:4〃,1‴-quaterphenyl]-4,4‴-diamine (4P-NPD) was used as the host material for FPtmND, FPtmmND, FPtOPhND, FPtppND, FPtCzND, FPtdmaND and FPtmorND. To improve the performance of hybrid white OLEDs, FPtmND, FPtOPhND, FPtdmaND and FPtmorND were selected to investigate for their hybrid fluorescence-phosphorescence white OLEDs with double emitting layer configuration by adopting CBP and 4P-NPD as the host material, respectively. Among them, FPtOPhND exhibited the best pure white EL having CIEx,y (0.33, 0.31) and a CRI as high as 91. Moreover, the white EL of FPtOPhND has little changes on both CRI and CIEx,y when the driving voltage varied between 7 and 10 V. The Maximum EL efficiencies of 11.8%, 25.9 cd A-1, or 11.6 lm W-1 have been achieved.

並列關鍵字

Platinum complex ； hybrid WOLED ； electroluminescence ； photoluminescence ； monomer ； excimer

參考文獻

9. (a) S. C. F. Kui, P. K. Chow, G. S. M. Tong, S.-L. Lai, G. Cheng, C.-C. Kwok, K.-H. Low, M. Y. Ko, C.-M. Che, Chem. Eur. J., 2013, 19, 69. (b) G. Li, T. Fleetham, J. Li, Adv. Mater., 2014, 26, 2931.

12. A. Poloek, C.-W. Lin, C.-T. Chen, C.-T. Chen, J. Mater. Chem. C, 2014, 2, 10343.

11. A. Poloek, C.-T. Chen, C.-T. Chen, J. Mater. Chem. C, 2014, 2, 1376.

20. G. Schwartz, S. Reineke, T. C. Rosenow, K. Walzer and K. Leo, Adv. Funct. Mater., 2009, 19, 1319.

22. T. Hirose, F. Helmich, E. W. Meijer, Angew. Chem. Int. Ed., 2013, 52, 304.