新穎深藍色螢光客發光體材料之開發與有機電激發光元件之應用

Abstract

具有高螢光效率的p-bis(p-N,N-diphenyl-aminostyryl)benzene(簡稱為DSA-Ph)搭配具有高薄膜穩定性之藍色主發光體2-methyl-9,10- di(2-naphthyl)anthracene (簡稱為MADN)，可得到一高發光效率(9.7 cd/A)和高穩定性(46,000小時)之藍色發光源，元件之色度座標為(0.16, 0.32)。但DSA-Ph元件的色飽和度無法達到全彩化OLED技術的需求，於是我們以縮短DSA-Ph分子內部共振系統長度的想法，合成出(E)-4,4’-bis(N,N-diphenylamino)stilbene (SB-1)、(E)-4,4’-bis(carbazolyl) stilbene (SB-2)、(E)-4,4’-bis(9,9-dimethylacridine)stilbene (SB-3)及(E)-4,4’-bis(2,2’-iminodibenzyl)stilbene (SB-4)。 以SB-1做為深藍光客發光體材料的元件效率為3.1 cd/A，並具有飽和的色度座標(0.15, 0.16)。但由於SB-1分子容易推疊，且SB-1元件在高低電流密度下的光色差異很大，並不是一個良好的藍光發光源。 於是我們利用分子設計的方式來改良SB-1分子的問題，因此合成出SK系列化合物。以4-N,N-diphenylamino-4’-[2-(4-N’,N’-diphenylamino- phenyl)–vinyl]biphenyl (SK-1)做為深藍光客發光體材料的元件效率高達4.7 cd/A，且具有更加飽和的色度座標(0.14, 0.13)，元件在高低電流密度下的表現也很穩定，符合目前OLED全彩化技術對深藍光元件的需求。

Anthracene-based blue host material, 2-methyl-9,10-di(2-naphthyl) anthracene (MADN) has a stable thin-film morphology. When doped with a highly fluorescent yield blue dopant, p-bis(p-N,N-diphenyl- aminostyryl)benzene (DSA-Ph), it achieved a highly efficient EL efficiency of 9.7 cd/A with a greenish-blue color of (0.16, 0.32) and a long operational lifetime of 46,000 h. But the color purity is still not adequate for full-color OLED display application. To develop deep blue dopants, the most straightforward solution is to shorten the conjugation length of DSA-Ph. Hence we synthesized (E)-4,4’-bis(N,N-diphenylamino)stilbene (SB-1)、(E)-4,4’-bis(carbazolyl)stilbene (SB-2)、(E)-4,4’-bis(9,9’-dimethylacridine) stilbene (SB-3) and (E)-4,4’-bis(2,2’-iminodibenzyl) stilbene (SB-4). The SB-1 doped device achieved an EL efficiency of 3.1 cd/A with a deep blue CIE coordinates of (0.15, 0.16). But the SB-1 molecule would aggregate easily and the device had problems of color shift under high/low drive current density. We modify the molecular structure of SB-1 to solve the problems and synthesized SK series compounds. The 4-N,N-diphenylamino-4’-[2-(4-N’,N’- diphenylamino-phenyl)–vinyl]biphenyl (SK-1) doped device achieved an high EL efficiency of 4.7 cd/A with a very saturate blue CIEx,y coordinates of (0.14, 0.13). The device performance under high/low drive current density is stable. Hence, the SK-1 can be employed as deep blue dopant of full color OLED technique.