标题: | 采用波导耦合效应提升固态白光有机电化学元件效率 Enhancing Device Efficiencies of Solid-State White Light-Emitting Electrochemical Cells by Employing Waveguide Coupling |
作者: | 郑佳毓 Cheng, Chia-Yu 苏海清 Su, Hai-Ching 照明与能源光电研究所 |
关键字: | 有机发光电化学元件;白光;波导;耦合;light-emitting electrochemical cells;white light;waveguide;coupling |
公开日期: | 2015 |
摘要: | 固态白光有机电化学元件已经受到高度的关注,因为它可能应用于显示及照明。虽然近几年来白光有机电化学元件的效率已有显着的改善,但为了能有更实际的应用,再进一步的提升仍是必须的。 在此研究中,我们藉由采用波导耦合效应的方式来提升白光有机电化学元件的效率。将两个掺有二氧化钛奈米粒子的透明光阻层嵌入于透明氧化铟锡电极和玻璃基板之间,而位于上层的透明光阻层,藉由调整半径25 nm二氧化钛粒子的浓度来调变其折射率,使ITO和位于下层的透明光阻层能达到有效的波导耦合作用,由于下层的透明光阻层含有半径250 nm的二氧化钛粒子,因此从ITO透过耦合作用而导出的光能被散射并重新导向正向出光。此外,被局限在玻璃基板内的光也能穿透至位于下层的透明光阻层中,并经过散射而贡献至正向出光。当被局限在ITO和玻璃基板中的光能够被有效的回收至正向时,采用波导耦合效应的白光有机电化学元件之外部量子效率和功率效率的峰值分别高达19.4 %和34.1 lm W–1,而这些效率为目前白光有机电化学元件中最高者,也证实了对于实现高效率白光有机电化学元件,采用波导耦合是个有效的方法。而具有散射作用的波导层结构之白光有机电化学元件除了能提升元件效率外,也因为在正向时能够平均不同视角下的电激发光频谱而改善了在照明应用上需要避免的颜色迁移现象。 Solid-state white light-emitting electrochemical cells (LECs) have received intense scientific attention owing to their potential applications in display and lighting. Although device efficiencies of white LECs have been improved significantly in recent years, further improvements are still required for practical applications. In this work, we demonstrate enhancing device efficiencies of white LECs by employing waveguide coupling. Two transparent photoresist (TPR) layers doped with TiO2 nanoparticles (NPs) are inserted between indium tin oxide (ITO) layer and glass substrate. By tuning the doping concentration of 25-nm TiO2 NPs in the upper TPR layer to adjust the refractive index, effective waveguide coupling between ITO layer and the lower TPR layer can be achieved. Since the lower TPR layer contains 250-nm TiO2 NPs, electroluminescence (EL) outcoupled from ITO layer can be scattered and redirected into the forward direction. Furthermore, the EL trapped in glass substrate can also transmit into the lower TPR layer and then is scattered to the forward direction. When the EL trapped in ITO layer and glass substrate can be effectively recycled into the forward direction, the peak external quantum efficiency and power efficiency obtained in white LECs employing waveguide coupling are up to 19.4 % and 34.1 lm W–1, respectively. These efficiencies are among the highest reported for white LECs and thus confirm that waveguide coupling would be useful for realizing highly efficient white LECs. In addition to enhanced device efficiencies, improved color migration of EL spectra, which is desired in lighting applications, can be obtained in white LECs with scattering waveguide layers since EL of different angles can be mixed in the forward direction. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT070258111 http://hdl.handle.net/11536/126097 |
显示于类别: | Thesis |