高分子電激發光二極體用聚[(2-苯基-3-芴基)-1,4-仲苯基乙炔]和聚[2,3-雙(對-芴基苯基)-1,4-仲苯基乙炔]

Abstract

本研究合成出三種單體，分別為1,4-bis(chloromethyl)-2-phenyl- 3-(9,9-dihexylfluoren-2-yl)benzene (M1)，1,4-bischloromethyl)-2,3-di-[4- (9,9-dihexylfluoren-2-yl)phenyl]benzene (M2)，1,4-bis(chloromethyl)-2- [p-(3,7-dimethyloctoxy)phenyl]-3-phenyl benzene (M3)，並成功的利用Gilch route聚合法，以t-BuOK當作鹼，合成出19種聚合物(P1~P19)。M1與M2聚合反應所得的單聚物P1、P3，因為導入立體障礙大的芴環，所以皆為藍綠光( 496 nm )的發光材料。 在本研究的第二部份，單體M1、M2分別與M3、1,4-bis (chloromethyl)-2,5-dimethoxybenzene，以及1,4-bis(chloromethyl)-2- (2-ethylhexoxy)-5-methoxybenzene ，進行共聚合反應，分別合成出共聚合物P2和P4~P19，這些聚合物的最大放射峰皆介於496∼556 nm的範圍之間，屬於藍綠光到黃綠光的發光材料。本研究亦製作了結構為ITO/PEDOT/Polymer/Ca(Al)的雙層有機電激發光二極體元件，並探討其發光特性。結果顯示所有的發光材料皆具有很高的分子量以及好的熱穩定性，在EL的性質中可以發現，大部分的發光材料均在較高電壓時有很明顯的藍位移現象，其中以P5的現象最為明顯，由536 nm (5V)藍位移至496 nm (12V)。 P17的亮度、EL效率隨電壓上升，有先降低之後再升高的現象，並達到最高亮度14070 cd/m2，以及最高效率1.51 cd/A，在最大亮度時，最大放射波長為528 nm，與本實驗室之前所合成的P19相比較，其效率更高，光色為更純的綠光(528 nm)。足以說明導入芴環取代基於PPV的側鏈上可以使光色有效的藍位移之外，也可以藉由調控電壓來改變光色。

Three kinds of monomers were synthesized in this study, i.e. 1,4-bis(chloromethyl)-2-phenyl-3-(9,9-dihexylfluoren-2-yl)benzene (M1), 1,4-bis(chloromethyl)-2,3-di-[4-(9,9-dihexylfluoren-2-yl)phenyl]benzene (M2), and 1,4-bis(chloromethyl)-2-[p-(3,7-dimethyloctoxy)phenyl]-3- phenyl benzene (M3). Monomers were polymerized via Gilch route using t-BuOK as base to gave substituted PPV derivatives (P1~P19). Polymer P1 and P3 were homopolymers, which were polymerized by M1 and M2 where both of them show a PL peak at 498 nm emitting blue-green light. This could be due to its large steric hindrance of fluorenyl substituents on the phenylene ring. In the second part of this thesis , monomer (M1、M2) was copolymerized with M3, 1,4-bis(chloromethyl)-2,5-dimethoxybenzene (DMeO-PPV), 1,4-bis(bromomethyl)-2-(2-ethylhexoxy)-5-methoxybenzene (MEH-PPV), to form copolymers (P2 and P4~P14) . All copolymers show blue green to yellow green light emition from 496 to 556 nm. Double-layer light-emitting devices consist of a simple ITO/PEDOT/Polymer/Ca(Al) configuration were fabricated and characterized. Most of the polymers exhibited very high molecular weights and good thermal stability. As far as the EL properties, most of the polymers show obvious blue-shift as the driving voltage increases. For example, polymer P5 emits green light at 536 nm at 5V. However its emitting light shifts to 496 nm at 12V. The maximum brightness and maximum external quantum efficiency of P17 can reach to 14070 cd/m2 and 1.51 cd/A. The EL λmax of P17 shows higher efficiency and good green color saturation compared to P19. The results demonstrate that introducing fluorenyl substituents into the PPV side chain can not only effect the blue-shift emitting color but also control emitting color by voltage variation.