有機電激發光元件之新穎綠色客發光體材料的合成與應用

Abstract

我們成功合成出一系列具有coumarin架構的新穎綠色客發光體材料-- ethyl-1,1,5,5,7-pentamethyl-11-oxo-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-10-carboxylate，簡稱 C-314P；10-acetyl-1,1,5,5,7-pentamethyl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]-quinolin-11-one，簡稱 C-334P；1,1,5,5,7-pentamethyl-10-(phenylsulfonyl)-2,3,6,7- tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one，簡稱C-340P；10-(1,3-benzothiazol-2-yl)-1,1,5,5,7-pentamethyl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]- pyrido[3,2,1-ij]quinolin-11-one，簡稱C-545P；10-[5,7-di(tert-butyl)-1,3-benzothiazol-2-yl]-1,1,5,5,7-pentamethyl-2,3,6,7- tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one，簡稱C-545PB；和1,1,5,5,7-pentamethyl-10-naphtho[1,2-d][1,3]-oxazol-2-yl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]- pyrido[3,2,1-ij]quinolin-11-one，簡稱C-520P；這一系列新穎綠色客發光體材料，其julolidine環上具有五個立體阻礙的甲基，與目前已應用於有機電激發光顯示器上的綠光發光材料10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo-[l]pyrano[6,7,8-ij]quinolizin-11-one，簡稱C-545T，只有四個甲基的分子設計有著很大的不同。而這一系列分子獨特的地方在於，其julolidine的氮旁邊α位置上具有兩個甲基；從立體化學的角度來看，其影響了分子的對稱性，使得分子較不易堆疊，降低在高濃度摻雜時濃度驟熄的問題。當以C-545P和C-545PB摻雜於主發光體Alq3中，其元件的發光效率與抗濃度驟熄的效應，皆較商業化使用的C-545T來的好；另外，C-545P和C-545PB其熱性質也較C-545T有明顯的提昇及改善。

We have discovered a new family of green fluorescent dopants based on coumarin structure --- ethyl-1,1,5,5,7-pentamethyl-11-oxo-2,3,6,7-tetrahydro- 1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-10-carboxylate (C-314P)；10-acetyl-1,1,5,5,7-pentamethyl-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]- pyrido[3,2,1-ij]-quinolin-11-one (C-334P)；1,1,5,5,7-pentamethyl-10- (phenylsulfonyl)-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (C-340P)；10-(1,3-benzothiazol-2-yl)-1,1,5,5,7-pentamethyl- 2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (C-545P)；10-[5,7-di(tert-butyl)-1,3-benzothiazol-2-yl]-1,1,5,5,7-pentamethyl- 2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (C-545PB) and 1,1,5,5,7-pentamethyl-10-naphtho[1,2-d][1,3]-oxazol-2-yl- 2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (C-520P). The molecular design of this new family of dopants, is based on five (penta) strategically placed “methyl” steric spacers as contrasted to 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H- benzo[l]pyrano[6,7,8-ij]quinolizin-11-one (C-545T) which only has four (tetra). The “P” family of dopants has the unique feature of having two gem-dimethyl groups situated alpha (a) to the nitrogen of the julolidine bearing the lone pair p-orbital. From the perspective of stereochemistry, the lack of molecular symmetry in the pattern of methyl substitution on julolidyl ring is expected to prevent molecular aggregation and delay the onset of quenching at high doping concentration as well.When fabricated as doped emitter in Alq3 hosted OLED devices, they show significant improvement in thermal properties, luminance efficiency and resistance to concentration quenching over the commercial dopant C-545T.