新型平面交流有机发光二极管的研究

Organic light-emitting diodes (OLEDs) are potential candidates for the next-generation solid-state lighting and displays, due to their light weight, flexibility, low cost, high contrast, fast switching speed and reliable colors. Ever since C. W. Tang invented sandwiched structure OLEDs in 1987, most of studies are based on this traditional structure, an active emitter layer positioned between two electrodes, and at least one of the electrodes must be transparent to allow the emitted light pass through. Indium tin oxide (ITO) is the most widely used transparent electrode material in OLED commercial products. However, indium is scarce and becoming more and more expensive as the growing demand for OLED displays, solar cells, touch screen panels and other electronic devices. There is a clear and urgent need for potential replacement of ITO as the transparent electrode in OLED devices. Here, we will focus on the fabrication of a novel ITO-free planar structure alternating current-driven OLED device (AC-OLED), which does not require transparent electrodes ITO for electrical input. The planar structure AC-OLED devices comprise four basic components: a pair of coplanar electrodes, dielectric layers, light-emitting layers and a transparent sensing layer. Metals (like silver, gold and aluminum) will be fabricated as the planar electrodes by vacuum evaporation. When a polar or ionic conductive solid transparent polymer composite film bridges between the two electrode stacks, light emission will occur, because of the dramatically change of the electric field direction. Therefore, ITO transparent electrode will not be necessary for OLED devices. This study will provide a new strategy toward the development of scalable, low-cost, flexible, printable, ITO-free OLED new products in the future.

有机发光二极管（OLED）具有自发光、广视角、高对比度等优点，在新一代显示领域具有极佳的应用前景。自三明治夹心结构OLED首次报道以来，OLED产品及研究大多基于这种结构，在上下两层电极间夹有发光层，且其中一个电极须为透明电极。氧化铟锡（ITO）是目前OLED使用最广泛的透明电极材料。然而，铟是一种稀有元素且地球储量低，因此亟需一种方案弱化或替代ITO作为透明电极在OLED器件中的必要性。本项目从器件结构角度从发，拟制备平面结构交流驱动OLED器件。在交流电场下，以不透明金属为平面电极，在器件顶层引入具有一定极性或离子导电性透明聚合物感应层，电场线方向和分布将随之改变，使器件平面电极层与感应层间形成电场并使器件工作发光。ITO透明电极将不再是这种器件的必要组成部分，从而实现弱化或替代ITO作为透明电极在OLED器件中的作用，为OLED器件中ITO替代问题提供一种新思路和解决方案。

电致发光器件是显示与智能传感领域的重要器件之一。自三明治夹心结构OLED首次报道以来，OLED产品及研究大多基于这种结构，在上下两层电极间夹有发光层，且其中一个电极须为透明电极。氧化铟锡（ITO）是目前OLED使用最广泛的透明电极材料。然而，铟是一种稀有元素且地球储量低，因此本项目执行中从两方面弱化或替代ITO作为透明电极在电致发光器件中的必要性。本项目从材料角度，分别成功制备了基于纳米银线透明导电膜、石墨烯/纳米银线复合透明导电膜、高透明高机械强度导电凝胶等性能优异的ITO透明电极替代材料。本项目从器件角度，成功构筑了交流平面电致发光器件，使得ITO透明电极不再是必要材料，达到了弱化ITO透明电极在电致发光器件中的必要性。进一步地，通过透明平面离子凝胶电极的研究，成功制备了具有可拉伸的、全透明的交流平面电致发光器件，拓展了本项目的研究深度与实际应用价值。该工作将来有望于用于智能机器人触觉及光子皮肤方面的应用。