Development of Multicolor Polymer Electroluminescent Devices by the Photobleaching Method

提出了一种制备微图案化多色有机电致发光器件的新的“光漂白方法”。在单层结构为氧化铟锡(ITO)/聚乙烯基咔唑/荧光染料/阴极金属分散的聚合物电致发光器件中，观察到来自分散染料的电致发光。当发出黄色发光的荧光染料Rubrene与蓝色染料一起掺杂到聚合物层中时，该器件从掺杂的Rubrene发出黄色光。为了调谐发光颜色，首先在旋涂形成的聚合物层中加入紫外光，使其光氧化而不发光。由于这种光漂白过程，UV曝光区域发出蓝色，而非曝光区域发出黄色。通过在紫外光照射过程中使用精细图案化的光掩模，成功地制作了微图案化的多色电致发光器件。通过使用合适的荧光染料作为掺杂剂，还开发了红、绿、蓝三色器件。

A novel "photobleaching method" for the fabrication of micropatterned multicolor organic electroluminescent devices has been developed. From single layer polymer EL devices with a structure of indium-tin oxide (ITO) / polyvinylcarbazole dispersed with fluorescent dyes / cathode metal, EL emission is observed originating from the dispersed dyes. When a yellow-emitting fluorescent dye, rubrene, is doped to the polymer layer, together with blue dye, the device emits yellow light from the doped rubrene. In order to tune the emission color, the rubrene-doped polymer layer is, first, exposed to ultraviolet (UV) light after formed by spin coating so that rubrene is photooxidized and becomes non-emissive. Due to this photobleaching process, the UV exposed area emits in blue while the non-exposed area yellow. By using a fine-patterned photomask during UV irradiation, micropatterned multicolor EL devices were successfully fabricated. Red, green blue, three color devices have also been developed by using appropriate fluorescent dyes as dopants.