Feng Jing, Okamoto Takayuki, Kawata Satoshi
Nanophotonics Laboratory, RIKEN (The Institute of Physical and Chemical Research), Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
Opt Lett. 2005 Sep 1;30(17):2302-4. doi: 10.1364/ol.30.002302.
We report enhancement of electroluminescence through opaque-topped metal cathodes in organic light-emitting devices (OLEDs), which are periodically corrugated in two dimensions. The enhancement is caused by grating-induced cross coupling and outcoupling of surface plasmons. The emission intensity observed at normal direction is enhanced by a factor of 4 compared with that of OLEDs with one-dimensionally corrugated metal cathodes and is higher than that observed from the transparent substrate side in uncorrugated OLEDs. We attribute the enhancement to the fact that the surface plasmons propagating in all lateral directions are coupled out into free space by the two-dimensional corrugated structure of the OLEDs. In addition, the emission from the transparent substrate side is also much enhanced owing to the efficient coupling out of the waveguide modes trapped in the emissive layer.
我们报道了在二维周期性波纹状有机发光二极管（OLED）中，通过不透明顶部金属阴极实现电致发光增强的现象。这种增强是由光栅诱导的表面等离激元的交叉耦合和外耦合引起的。与一维波纹状金属阴极的OLED相比，在法线方向观察到的发射强度提高了4倍，并且高于在无波纹OLED中从透明基板侧观察到的强度。我们将这种增强归因于这样一个事实，即沿所有横向传播的表面等离激元通过OLED的二维波纹结构耦合到自由空间中。此外，由于被困在发光层中的波导模式的有效外耦合，从透明基板侧的发射也大大增强。
