紫外光有機電化學元件

Abstract

紫外光的有機電激發光技術的應用前景廣闊，除了在全彩顯示技術上面，由於紫外光具有高能量低波長，還能應用於生醫技術、光蝕刻、光感應、資料儲存技術。有機發光電化學元件Light-Emitting Electrochemcial Cells是近年來新發展出來的一種有機電激發光技術，與傳統有機發光二極體 OLED 比起來具有更簡易的單層發光結構、使用溶液製成、可使用非活性金屬以及低電壓低功耗等優點。 本論文中元件以溶液製成技術製成，在玻璃基板上使用銦錫氧化物為陽極，鈣/銀為陰極，分別以商用的OLED Phosphorescent Host材料4,4'-bis(carbazol-9-yl)biphenyl (CBP)，以及Electron Transport材料2,2',2''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi)為主體材料，摻入導電高分子材料Poly(N-vinylcarbazole) (PVK)，增添元件中電洞傳輸速度使元件中的載子傳輸能達到平衡，減少主體材料分子間互相作用導致的猝息以提升效率，同時能夠使得分子堆疊平整，減少不均勻的堆疊，使元件光色更純，最後再摻入有機鹽類tetrabutylammonum tetraperchlorate (TBAClO4)，提供在電場下可移動的離子，製作出兩種單層結構的紫外光有機發光電化學元件，其電激發光頻譜峰值分別位於390 nm以及377 nm，頻譜半高寬皆分別少於100 nm以及60 nm，其中以CBP為主體的元件其外部量子效率0.64 %，功率效率為2.43 mW/W，光輸出為13.7μW/ cm2。為文獻上首先製作出的紫外光LEC元件，深具學術價值。

The ultraviolet organic light-emitting devices (UV OLEDs) have potential applications not only in biomedical, biological sensors and etching technologies, but also in full-color displays and high-density information storage devices. Light-emitting electrochemical cells (LECs) devices have several advantages such as requiring only one single emissive layer that can be easily processed from solutions process, low bias voltage and using air-stable electrodes in comparison with OLEDs. In this work we fabricate the ultraviolet light-emitting electrochemical cells (UV LECs) for the first ime. Two UV LEC devices have been fabricated by solution process. The first UV LEC contains an emission layer of 2,2',2''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) the as light-emitting material. The other one uses 4,4'-bis(carbazol-9-yl)biphenyl (CBP) as the light-emitting material. Both devices are doped with organic salt TBA+(ClO4)- and poly(N-vinylcarbazole) (PVK) to improve carrier transport properties and carrier balance, which can enhance the device efficiency and purified the EL spectrum. Bias-voltage and doped-concentration dependence on current density, light output, device efficiency were discussed. Two UV LEC have EL spectrum centers at 390 nm and 377 nm and the FWHM lower than 100 nm and 60 nm, respectively. The second UV LEC achieved external quantum efficiency, light output, and power efficiency up to 0.64 %, 13.7 μW/cm2 and 2.43 mW/W, respectively. It is the first reported UV LEC and thus this work shows a great breakthrough in the research filed of LECs.