奈米散射膜對有機發光元件特性改善之研究

Abstract

有機發光元件由於其優異的特性在近年來受到各方的關注，尤其是平面顯示器和固態照明的應用。特別是發展高效率的有機發光元件以減少能源消耗是目前重要的課題之一。隨著電激磷光元件的發展，實際上有機發光元件的內部量子效率已經可以接近100% 。然而，由於元件內部各層材料折射率不匹配，光將因為全反射而侷限在有機發光元件當中，使得傳統下發射型有機發光元件的出光耦合效率一般約僅有20% 。在本篇論文中我們將製備並應用奈米散射膜於有機發光元件上。通過整合奈米散射膜在透明電極ITO與玻璃基板之間，元件外部量子效率比起傳統下發射型有機發光元件可提高為1.96倍，在cd/A效率可提高為2.04倍。同時，奈米散射膜有助於改善元件不同視角的色彩變化，以及幫助各視角光強度分佈接近理想的Lambertian分佈。

Organic light-emitting devices (OLEDs) are very attractive due to their potential application in flat-panel displays and solid-state lighting. Especially, developing high power-efficiency devices to reduce energy consumption is one of the critical issues. Recently, the internal quantum efficiency (IQE) of electrophosphorescent organic light-emitting devices has approached nearly 100%. However, due to refractive-index mismatch between different material layers of OLEDs, light in OLEDs cannot be extracted effectively and suffers from total internal reflection. The out-coupling efficiency of conventional bottom-emitting devices is limited to about 20%. Here we demonstrate a method to enhance out-coupling of OLEDs. By integrating nano-scattering films between the ITO electrode and the glass substrate, the external quantum efficiency of OLEDs can be enhanced by 1.96 times and the cd/A efficiency can be enhanced by 2.04 times compared to conventional bottom-emitting devices. The nano-scattering films can further decrease color shift over viewing angles, and the emission pattern becomes closer to the Lambertian distribution.