應用在有機電激發光顯示器之新紅色螢光摻雜物的合成與性質研究

Abstract

應用在有機電激發光顯示器之新紅色螢光摻雜物 的合成與性質研究 研究生：李世男 指導教授： 陳金鑫 博士 國立交通大學應用化學研究所 摘要 現今商業上已有的有機電激發光二極體Organic Light Emitting Diodes (簡稱OLED) 紅光摻雜物中，使用最廣的就是DCJTB： 2-{2-(tert-butyl)-6-[(E)-2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H- pyrido[3,2,1-ij]quinolin-9-yl)-1-ethenyl]-4H-4-pyranliden}malononitrile， 當以tris(8-hydroxyquinolinolato) aluminum (簡稱Alq3)為主發光體作成元件時，在最佳的發光效率時，光色偏橘；而為了達到飽和的紅光時，必須提高摻雜濃度，此時又會有濃度驟息的現象發生。 本論文利用分子設計的原理，選擇在DCJTB的 8號碳位置上接上推電子基。希望藉由改變DCJTB的能階及增加立體阻礙來達到改善光色及避免濃度驟息現象的發生。 據此，本論文合成出 DCJTB-OM：2-{2-(tert-butyl)-6-[(E)-2- (8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1- ij]quinolin-9-yl)-1-ethenyl]-4H-4-pyranliden}malononitrile、 DCJTB-OE：2-{2-(tert-butyl)-6-[(E)-2-(8-ethoxy-1,1,7,7-tetramethyl- 2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)-1-ethenyl]-4H-4- pyranliden}malononitrile及DCJTB-OP：2-{2-(tert-butyl)-6-[(E)-2-(8- isopropoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)-1-ethenyl]-4H-4-pyranliden}malononitrile 改良後的DCJTB-OM、DCJTB-OE及DCJTB-OP，跟DCJTB的固態螢光作比較，可以發現當以Alq3為主發光體，三化合物在固態螢光中，雖然發光量子效率比DCJTB差，但能量轉移效果比DCJTB好。個別比較不同的摻雜濃度比例時，無論濃度比例低或高，只要摻雜物的摻雜濃度相同時，DCJTB-OM、DCJTB-OE及DCJTB-OP的光色皆較紅、較飽和。 將三個DCJTB-OR化合物製成元件時， 由量測到的CIE 1931座標值來看，當比較2%~4%間相同的摻雜濃度時，只要三種材料摻入Alq3中的濃度相同時，DCJTB-OM、DCJTB-OE及DCJTB-OP元件的光色皆比DCJTB的元件光色接近飽和的紅光。而在計算能階時，發現DCJTB-OM、DCJTB-OE及DCJTB-OP的能階變得較小，印證了光色變紅的緣故。此外再比較元件抗濃度驟息的趨勢時，發現DCJTB-OM、DCJTB-OE及DCJTB-OP由摻雜濃度2%增加到4%時，三者發光量子效率雖然比DCJTB低，但是降低的幅度皆比DCJTB還小。換言之，三個化合物在抗濃度驟息的效果上比DCJTB還好。推測是因為導入了具立體障礙的基，造成摻雜濃度增加時，分子彼此間的較不易靠近，可有效減少濃度驟息現象的影響。 因此本論文的結論就是，合成出的三個化合物雖然做成元件時發光量子效率比DCJTB差，但是三個化合物改善了DCJTB元件發偏橘光的現象，且同時提昇抗濃度驟息的能力。

Synthesis and Characterization of New Red Dopants for Organic Electroluminescence Student：Shih-Nan Lee Advisor：Dr. Chin Hsin Chen Institute of Applied Chemistry National Chiao Tung University ABSTRACT One of the most widely used red dopants in commercial OLED products to date is DCJTB, 2-{2-(tert-butyl)-6-[(E)-2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro- 1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)-1-ethenyl]-4H-4-pyranliden}malononitrile . When fabricated a device of [ITO/CuPc/NPB/dopant:Alq3/Alq3/Mg:Ag], the color tends to look orange at optimal dopant concentration in tris(8-hydroxyquinolinolato) aluminum (Alq3), whereas at high dopant concentration in order to obtain the saturated red , the EL efficiency moved drop due to concentration quenching. Through molecular design, we hope to shift the color to a saturated of red (x=0.65,y=0.35) by introducing a donating group at the C-8 position of DCJTB, which may change the energy level and increase steric hinderance to alleviate concentration quenching. DCJTB-OM, 2-{2-(tert-butyl)-6-[(E)-2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro- 1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)-1-ethenyl]-4H-4- pyranliden}malononitrile, DCJTB-OE, 2-{2-(tert-butyl)-6-[(E)-2-(8-ethoxy- 1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)-1- ethenyl]-4H-4-pyranliden}malononitrile and DCJTB-OP, 2-{2-(tert-butyl)- 6-[(E)-2-(8-isopropoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H- pyrido[3,2,1-ij]quinolin-9-yl)-1-ethenyl]-4H-4-pyranliden}malononitrile were synthesized in this thesis according to this idea. Comparing the color of their solid PLs, the quantum yield of DCJTB-OM, DCJTB-OE and DCJTB-OP are lower than that of DCJTB , but they are more saturated than DCJTB at the same dopant concentration in Alq3, and energy transfer from Alq3 to DCJTB-OM and DCJTB-OP are formed to be slightly more efficient. When fabricated into a device, DCJTB-OM, DCJTB-OE and DCJTB-OP are found to be more saturated in terms of CIE coordinate 1931 at the same dopant concentration in Alq3. Calculation of energy level shows these bandgap energies (Eg) are somewhat smaller which results in the descend red shift of these color. Comparing the trend of resistence to concentration quenching effect, DCJTB-OM, DCJTB-OE and DCJTB-OP are also appear to be better than DCJTB, although the luminance efficiency of DCJTB-OM、DCJTB-OE、DCJTB-OP are lower than DCJTB. In conclusion, although the luminance efficiency of DCJTB-OM, DCJTB-OE and DCJTB-OP are lower than DCJTB, they improve the color of DCJTB device from orange to more saturated red color and at the same time delay the onset of these concentration quenching.