9,10-二(2-萘基)蒽應用於藍光與紅光有機電激發光元件之性質研究

Abstract

對於有機電激發光元件，假使能利用單一主發光體來激發不同光色之客發光體，對於應用在全彩化技術上將是一大優點。因此本論文選擇以藍光發光體當作主發光體，進行摻雜藍光及紅光客發光體的實驗，以實現利用單一發光體激發不同光色客發光體的想法。 以9,10-di(2-naphthyl)anthracene(ADN)為藍色主發光體之有機電激發光元件，其發光效率會隨著發光層厚度變化而改變，且元件會因有機發光材料折射率不同造成微共振腔效應。經由細微的調整發光體ADN膜厚厚度，以及最佳化的客發光體2,5,8,11-tetra(tert-butyl)- perylene (TBP)摻雜濃度時，可以得到比現今文獻上報導過最好藍光材料anthracene系列的元件更好的數據，其元件發光效率可以高達5.1 cd/A，CIE 1931座標(x = 0.14; y = 0.22)。 當紅光螢光4-(dicyanomethylene)-2-(t-butyl)-6- (1,1,7,7 -tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB)摻雜於藍光主發光體ADN時，發現其元件發光光色會經過藍位移形成橘光光色。因此選擇紅外光發光的4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7,8- pentamethyljulolidyl-9-enyl)-4H-pyran (DCJTB-M)摻雜於藍光主發光體ADN，發現其元件發光光色不錯且發光效率可以高達1.52 cd/A，CIE 1931色度座標(x = 0.65; y = 0.35)，其元件光色已經是理想紅光發光，並且發現元件在高低電流操作下其發光效率是不會發生改變的，是維持水平的狀態，這樣的優點對於商業顯示器的應用是一個相當大的優勢。

If we can use one host emitter to excite different guest dopants to get R.G.B. color in organic light emitting devices (OLEDs), it will be a great advantage for full color application. Therefore in this thesis we studied the doping of blue and red guest molecules in a single blue host emitter to demonstrate the feasibility of this idea. Blue EL emission of 9,10-di(2-naphthyl)anthracene (ADN) based emitter in OLEDs is highly dependent upon its emitter thickness and attenuated by the microcavity effect of the emitter. By carefully tuning the emitter thickness of ADN and optimizing the doping concentration of 2,5,8,11-tetra(tert-butyl)perylene (TBP), one of the highest efficiencies ever reported for the anthracene based blue emitter at 5.1 cd/A with a CIE 1931 of (x=0.14; y=0.22) is achieved. The device of 4-(dicyanomethylene)-2-(t-butyl)-6-(1,1,7,7- tetramethyl-julolidyl-9-enyl)-4H-pyran (DCJTB) doped in ADN resulted in a bathochromic shift in CIE coordinates from red to orange. By choosing a dopant which absorbs in the infrared, such as 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7,8-9-enyl)]-4H-pyran (DCJTB-M). When DCJTB-M doped in ADN, we could achieve an efficiency of 1.52 cd/A with a CIE 1931 of (x=0.65; y=0.35) at 3.5 % doping concentration in the red region. The luminance efficiency is found to be essentially independent upon the drive current – a criterion which is important in the OLED module design and manufactuing.