2016-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/689835摘要：在有機電激發光二極體發展中，藍光元件效率及壽命為一重要之技術瓶頸。藍色磷光元件的效率高但是壽命短，藍色螢光元件的壽命可以接受，但是其效率低。藉由合成新的發光材料，具備相近的單重態及三重態能量，以『熱活化延遲螢光』的機制放光，理論上可以兼顧效率及壽命，然而目前有機發光材料仍在發展中。 本計畫的目的，係為利用現有發展較成熟的藍光螢光發光材料（如&#33981;衍生物），其兩個三重態激子能量略高於單重態激子能量，因此兩個三重態激子可以融合成一個單重態激子放出螢光，亦即所謂『三重態-三重態上轉換』，如此則可以使用到不放光的三重態能量，從而提高效率。然而這樣的物理機制需要用到兩個激子轉換成一個光子，其內部量子效率有其極限（<62.5%）。因此，我們在此提出，利用低能隙的主體材料，摻雜具備激子融合特性之有機材料，載子在低能隙材料上傳輸及復合，藉由能量轉移的機制，將能量轉移至具備激子融合特性有機材料之三重態，再經過『三重態-三重態上轉換』放出藍色螢光。由於載子係於低能隙材料上傳輸，因此，與一般寬能隙藍光元件相比，其驅動電壓較低，可以彌補內部量子效率的不足，從而製作出高功率效率及長壽命的藍光元件。 <br> Abstract: Organic light-emitting diode (OLED) is a promising display and lighting technology. However, one important technical bottleneck for OLED is the low efficiency and short lifetime of blue device. Typically, phosphorescent material is used for boosting up the efficiency. However, the lifetime of blue phosphorescent OLED is very short. On the other hand, the efficiency of blue fluorescent OLED is low, although the lifetime is acceptable. Recently, by synthesizing new materials exhibiting close singlet and triplet states, it is possible for triplet excitons to upconvert to singlet states through reverse intersystem crossing by means of thermal energy, which is called "thermally activated delayed fluorescence (TADF)." High efficiency and long lifetime blue OLED can be obtained theoretically by such TADF mechanism. However, the TADF materials are still developing. The objective of this project is to use some "relative" mature blue fluorescent materials (such as anthracene derivatives) which exhibit very low triplet-state energy (about more than half of the singlet-state energy). Hence, two triplet excitons can fuse into one singlet exciton for fluorescent emission, which is called "triplet-triplet annihilation upconversion (TTAUC)." And the triplet excitons contribute to light emission and increase the efficiency. However, such emission mechanism needs two excitons to generate one photon, and hence limits the internal quantum efficiency (IQE< 62.5%). Here, we propose to use a host material with low energy bandgap, doped with the fluorescent blue emitter exhibiting exciton fusion characteristics. Carriers transport and recombine on such low-bandgap host, and excitons on the host transfer the energy to the triplet states of the blue fluorescent materials. Then, blue fluorescence emission can be achieved by means of TTAUC. Because carrier transport on the low-bandgap host, the required driving voltage is lower (compared to blue fluorescent and phosphorescent OLED) which compensates the lower IQE and hence it is possible to achieve blue OLED with high power efficiency (in terms of lm/W) and long lifetime.有機電激發光元件壽命效率OLEDlifetimeefficiency