高效率紅外光有機發光電化學元件

Abstract

紅外光科技被應用於各種領域已有相當長的時間，而製作高效率且低 成本的紅外光源一直是重要的課題，其中有機發光電化學元件所具有的低 成本優勢及低操作電壓的特性與可製作成可撓元件具有相當大的發展潛 力，但目前無論是以共軛高分子為發光材料，或是離子性過渡金屬錯合物 為發光材料的紅外光有機發光電化學元件都面對效率不高的問題。 本論文以溶液製程製作出單層結構的紅外光有機發光電化學元件，為 研製高效率紅外光有機發光電化學元件，元件的製作使用銦錫氧化物為陽 極，鋁為陰極，應用主客體摻雜發光系統，以橘光磷光材料離子性過渡金 屬錯合物[Ir(ppy)2(dasb)]+(PF6)─為主體材料，高效率的紅外光螢光雷射染料 3,3'-Diethyloxatricarbocyanine iodide 為客體材料，並添加了有機鹽類 BMIM+(PF6)-混合而成的發光層，利用磷光敏化的機制使元件效率提升。 為了得到元件的最大效率及光色飽和，本論文以施加不同的操作電壓 2.4 V 與2.5 V 對含有不同的客體摻雜濃度的元件0.5 wt.%、1 wt.%及1.5 wt.%，探討操作電壓與客體摻雜濃度對元件的電流密度、效率及發光頻譜 特性的影響。最後以客體摻雜濃度1 wt.%的元件在2.4 V 偏壓達成元件外 部量子效率0.82 %、發光強度0.58 μW/cm2、功率效率5.6 mW/W，電激 發光頻譜峰值位於730 nm，頻譜半高寬60 nm 高效率且光色純淨的紅外光 有機發光電化學元件。

The infrared technology has been applied to the fundamental study and practical applications in a number of important sectors for a long time. How to fabricate efficient and low-cost devices is always an important issue. Lightemitting electrochemical cells (LECs) devices show several advantages such as low cost, low bias voltage, and flexibility. But infrared LECs devices based on conjugate polymers or transition metal complexes exhibit low device efficiencies. In this work, the single-layered infrared LECs devices are fabricated by solution process. The emission layer uses host-guest doping system containing orange emitting phosphorescent ionic transition metal complex [Ir(ppy)2(dasb)]+(PF6)─ as the host, efficient fluorescent infrared laser dye 3,3'-Diethyloxatricarbocyanine iodide as the guest and organic salt BMIM+(PF6)-, utilizing phosphor-sensitization to promote performance of device. Host-guest LEC devices are fabricated with guest concentrations of 0.5 wt.%, 1 wt.% and 1.5 wt.%. Bias-voltage and guest-concentration dependence on current density, device efficiency and electroluminescence (EL) spectrum are discussed. The LEC devices doped with 1 wt.% guest concentration achieve quantum external quantum efficiency, light output, and power efficiency up to 0.82 % , 0.58 μW/cm2 and 5.6 mW/W, respectively. The EL spectrum centers at 730 nm and the FWHM is about 60 nm. Such results show that phosphor-sensitized infrared LECs are potential candidates for efficient infrared light sources.