新穎的矽烷官能基藍光主客發光體材料合成與有機電激發光元件之應用

Abstract

9,10-di(2-naphthyl)anthracene (ADN) 為最廣泛作為有機電激發光二極體 (Organic Light Emitting Devices；OLEDs) 的藍光主發光材料之一。然而，ADN不良的薄膜熱穩定性卻有可能減損了元件的壽命。為了改善薄膜熱穩定度，我們決定合成一系列在anthracene 9號位置接上tetraphenylsilane以及10號位置接上取代基的新穎藍光主發光材料，藉由tetraphenylsilane的非平面星狀結構，來破壞分子的對稱性。在本論文中，我們合成：[4-(9-anthryl)phenyl]-triphenyl Silane (ASi)、triphenyl-4-(10- phenyl-9-anthryl) phenyl Silane (PASi)、{4-[10-1-naphthyl]-9-anthryl}phenyl}triphenyl Silane (1-NASi) 及 {4-[10-2-naphthyl]-9-anthryl]phenyl}-triphenyl Silane (2-NASi)。 藉由原子力顯微鏡的分析結果指出，接上取代基的PASi、1-NASi及2-NASi，在經過熱處理後，其薄膜性質仍然很好，相對於沒有取代基的ASi及ADN，確實提升其固態薄膜熱穩定性。 為了要減少全彩化製成時的能量耗損率，現今對藍光 OLED 之需求是以高飽和度作為主要考量，而以此系列作為主發光體可以得到高飽和度及高薄膜穩定性的藍光元件，其中又以取代基為1-naphthalene的1-NASi顏色最藍，未摻雜時CIEx,y (0.15, 0.06)，效率為0.47 cd/A，摻雜深藍光客發光材料SA-biph時CIEx,y (0.15, 0.11)，效率為1.96 cd/A，此結果符合目前趨勢的取向，更是能應用在全彩化的主發光體材料中。

我們修改了發淺藍光色的客發光材料p-bis(p-N,N-diphenyl-aminostyryl) benzene(DSA-Ph) 利用取代基Tetraphenylsilane來取代一邊的Triphenyl- amine，合成出{4-[2-(tetraphenylsilyl- phenyl)-vinyl]-phenyl}-biphenylamine (Si-Nbiph)，由於縮短了共軛鏈長度，使的其發深藍色的光；另一方面歸因於Tetraphenylsilane的立體阻礙，使的此材料在製作元件時有抗濃度驟熄的效應。當它摻雜在穩定的藍光主發光材料2-methy-9,10-di(2-naphthyl) anthracene (MADN) 時，濃度可以高達15 %，且其發光效率在20 mA/cm2電流密度下時為3.93 cd/A，而光色在深藍光的範圍，CIEx,y座標值在(0.15, 0.15)。

ADN is one of the most widely used blue host materials in Organic Light Emitting Devices (OLED). However the poor thermal stability of the thin films may short the lifetime and stability of the devices. In order to enhance the thin-film morphological stability,we decided to introduced substituents at C-10 position and tetraphenylsilane at C-9 position of anthracene. Owing to the starbust moiety of silane, we can disrupt the molecular symmetry. In this thesis, we synthesized [4-(9-anthryl)phenyl]-triphenyl Silane (ASi)、triphenyl-4-(10- phenyl-9-anthryl)phenyl Silane (PASi)、{4-[10-1-naphthyl]-9-anthryl}phenyl}- triphenyl Silane (1-NASi) and {4-[10-2-naphthyl]-9-anthryl}phenyl}-triphenyl Silane (2-NASi). By the atomic force microscopy (AFM), these thin-film morphology of PASi、1-NASi and 2-NASi are very smooth without any sign of crystallization after annealing at 95 oC for 1 hour as contrasted to what were observed for ADN and ASi. In order to lower the power consumption in making full color display, the color saturation is a crucial factor especially for deep blue OLED. High color saturation and stable thin film character can be achieved by using the series of host materials mentioned above in blue devices. Among those host materials, 1-NASi has the most saturated blue color. The undoped host achieved a luminance efficiency of 1.96 cd/A with a CIEx,y coordinate of (0.15, 0.06). When doped with SA-biph, it achieved a luminance efficiency of 1.96 cd/A with a CIEx,y coordinates of (0.15, 0.11).

We have synthesized a new deep blue dopant {4-[2-(tetraphenylsilyl-phenyl) vinyl]-phenyl}-biphenyl amine (Si-Nbiph) based on organic Silane fluorescent dye and modified the styrylamine-based blue dopant p-bis(p-N,N-diphenyl -aminostyryl)benzene (DSA-Ph) by replacing triphenylamine with Silane. Owing to the steric hindered characteristic of silane moiety, the problem of dopant concentration quenching can be suppressed. When Si-Nbiph was doped up to 15% in the stable blue host material 2-methy-9,10-di(2-naphthyl) anthracene (MADN), the blue devices were achieved a luminance yield of 3.93 cd/A at 20 mA/cm2 with a near saturated CIEx,y 1931 color coordinate of (0.15, 0.15).