上發光有機電激發光二極體元件結構開發與可撓曲基板應用

Abstract

我們運用傳統C545T綠光下發光元件結構當作基礎模型，替換玻璃使用不鏽鋼基板(Stainless steel foil, SS) 並鍍上高反射率的銀、鋁金屬作為上發光元件陽極，藉由p型材料(Tungsten oxide, WO3)摻雜於(4,4’-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl, NPB) 當電洞注入層及n型材料(Dipotassium phthalate, PAK2)或(Cesium carbonate, Cs2CO3) 摻雜於(4,7-Diphenyl-1,10-phenanthroline, BPhen) 為電子注入層以及在陽極金屬與電洞注入層間再加入一層WO3薄膜，能夠有效地使金屬與有機材料能階匹配，搭配雙層半穿透陰極Ca/Ag以降低電子的注入能障，量測覆蓋層(Capping layer)反射及穿透率，調變結構至最佳的微共振腔厚度，使用Alq3摻雜C545T作為此綠光上發光元件發光層其效率在SS基板上20 mA/cm2下電流效率可達26.7 cd/A和能量效率19.8 lm/W、CIEx,y色座標為(0.244, 0.719)轉至75°時位移至(0.196, 0.724)，ΔCIEx,y為±0.05。

Highly efficient flexible top-emitting organic light emitting diodes (FTOLED) employing highly reflective Ag or Al as anode and a semitransparent Ca/Ag as cathode was fabricated on SS substrate by incorporating p-dopant (tungsten oxide, WO3) and n-dopant (dipotassium phthalate, PAK2) or (cesium carbonate, Cs2CO3) in hole transparent layer (4,4’-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl, NPB) and electron transparent layer (4,7-Diphenyl-1,10-phenanthroline, BPhen), respectively. Proper insertion of anodic buffer layer (WO3) between anode and HIL as bilayer hole injection layer is effective in overcoming the deficiency of low work function of anode. Ca/Ag double layer films with capping layer were prepared on the glass substrate for the investigation of optical characteristics, along with an optimized microcavity structure. A green fluorescent C545T doped Alq3 TOLED on SS substrate achieved high EL efficiencies of 26.7 cd/A and 19.8 lm/w with a highly saturated green color of (0.244, 0.719) and at ±75 degree the color shift of ΔCIEx,y was ±0.05.