藍色有機發光二極體相關材料之合成與應用

Synthesis and Characterization of Materials for Blue Organic Light-Emitting Diodes

吳承龍(Cheng-Lung Wu)

指導教授 ： 陳昭岑

國立臺灣大學/理學院/化學研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.02053

摘要

本篇論文可分為三大部分，第一與第二部分是設計並合成用於藍色磷光OLED之主體材料，第三部分則是著重於開發藍色螢光發光材料。
在第一部份，我設計一系列的雙螺旋環雙芴衍生物(bis-(9,9’-spirobifluorene) 做為主體材料並在兩組螺旋環雙芴之間設計不同的主族元素做為架橋原子(bridged atoms)，利用架橋原子去嘗試阻斷兩組π共軛系統，以維持螺旋環雙芴本身高三重態能隙的特性，所得之主體材料被用於藍色磷光OLED元件的製作。其中SP2PO與SP2SO2所製之元件其外部量子效率分別可達6.0與6.1%。
在第二部分則是嘗試設計具有雙極性之主體材料，修飾之前合成2-iodo-9,9’-bifluorene的合成路徑，可以成功的合成不對稱雙取代或三取代螺旋環雙芴衍生物，藉由不同的取代基數量調控主體材料的電洞與電子傳輸能力，所得之主體材料被用於藍色磷光OLED元件的製作。其中CzdSPPO與CzdSP2PO所製之元件其外部量子效率分別可11.4與11.5%。
第三部分則是以9,10-diphenylanthracene為藍色螢光材料的主要架構，嘗試在C-2上修飾具防止堆疊與結晶的取代基，包括C－C (TMPDPA)、C－Si (TPSDPA)、C－P (PPODPA)、C－B (BMTDPA)和C－N (NPADPA)鍵，由這幾個材料在溶液下的螢光放光波長與溶液下螢光量子產率表現，我挑選TMPDPA進行衍生，在蒽之C-9和C-10苯基分別接上傳輸電洞的咔唑(CBZDPA)或是傳輸電子的oxadiazole (OXDDPA)；所得之藍色螢光材料被用非摻雜式藍色螢光OLED的製作。除了PPODPA之外，其餘DPA衍生物電激發光的效率皆有明顯的提高，尤其是CBZDPA與OXDDPA所製之元件其外部量子效率分別可達4.5與4.0%，且電激發光之顏色屬於藍色，CIE色座標分別落在(0.17, 0.17)與(0.16, 0.18)，此元件效率之提高歸功於CBZDPA與OXDDPA結構上的電荷傳輸設計。

關鍵字

主體材料 ； 藍色螢光材料 ； 有機發光二極體

並列摘要

My doctoral dissertation can be divided into three parts. The first and the second parts were focused on designing and synthesizing host materials for the application of blue phosphorescence organic light-emitting diodes. The third part was focused on developing of blue fluorescence light-emitting materials.
In the first part, I designed a series of heteroatom-bridged bis-(9,9’-spirobifluorene) derivatives as the host materials. The bridged atoms can maintain the high triplet state energy gap of 9,9’-spirobifluorene via disconnecting π-conjugated systems. The materials were fabricated in the application of blue phosphorescence organic light-emitting diodes. SP2PO and SP2SO2 OLEDs exhibited the best external quantum efficiency of 6.0 and 6.1 %, respectively.
In the second part, I attempt to design bipolar host materials based on 9,9’-spirobluorene structure. I successfully synthesized unsymmetric two- or three- substituent 9,9’-spirobilfuorene via modifying the synthesis strategy of 2-iodo-9,9’-spirobifluorene. The hole and electron mobility of host materials can be adjusted by different number of substituents. The materials I synthesized were made into devices for blue phosphorescence organic light-emitting diodes. CzdSPPO and CzdSP2PO OLEDs exhibited the best external quantum efficiency of 11.4 and 11.5 %, respectively.
In the final part, I designed and synthesized a new series of 9,10-diphenylanthracene (DPA)-based blue fluorophores. These fluorophores have bulky substituent on C-2 position, such as triphenylsilane of TPSDPA and mesitylene of TMPDPA. C-2 substituent also includes electron transport diphenylphosphine oxide of PPODPA and dimesitylene borane of BMTDPA, or hole transport of N-phenylnaphthalen-1-amine of NPADPA. According to the emission wavelength in solution and the performance of quantum yields of these fluorophores, I selected TMPDPA as model compound for further modification. For TMPDPA blue fluorophores, 9,10-diphenyl substituents of the anthracene core were attached with hole-transporting 9H-carbazole (CBZDPA) and electron-transporting 2-phenyl-1,3,4-oxadiazole (OXDDPA) on para- and meta-position, respectively. These DPA-based fluorophores were fabricated as light-emitting materials in non-dopant blue fluorescent devices. Except of PPODPA, electroluminescence efficiency of these DPA derivatives was all found significantly improved. Particularly, CBZDPA and OXDDPA OLEDs exhibited the best external quantum efficiency of 4.5 and 4.0 % with true blue colour, CIEx,y (0.17, 0.17) and CIEx,y (0.16, 0.18), respectively. Improved electroluminescence efficiency can be attributed to the molecular charge transport design of CBZDPA and OXDDPA.

並列關鍵字

Host Materials ； Blue Fluorescent Materials ； Organic Light-Emitting Diodes

參考文獻

[14] C. W. Tang, 2000 SID at Tapei, 6.

[2] W. Helfrich and W. G. Schneider, Phys. Rev. Lett., 1965, 14, 229.

[3] W. Helfrich and W. G. Schneider, J. Chem. Phys., 1966, 44, 2902.

[4] C. W. Tang and S. A. VanSlyke, Appl. Phys. Lett., 1987, 51, 913.

[10] J. Kido, K. Hongawa, and K. Nagai, Appl. Phys. Lett., 1993, 63, 2627.