High-Contrast Tandem Organic Light-Emitting Devices Employing Semitransparent Intermediate Layers of LiF/Al/C-60

作者：Ding Bao Fu^*; Alameh Kamal

来源：Journal of Physical Chemistry C, 2012, 116(46): 24690-24694.

DOI：10.1021/jp308816w

The use of a black cathode with a metal-organic-metal structure is an attractive approach to achieving a high contrast organic light emitting device (OLED) for future generation flat panel displays. However, the large reduction in OLED power efficiency is currently restricting the use of the black cathode for industrial applications. In this paper, a high contrast, high:efficiency tandem OLED employing a black cathode is proposed and experimentally demonstrated The OLED is implemented by stacking two organic phase tuning layers between a composite intermediate layer of LiF/Al/C-60 and LiF/Al and optimizing their thicknesses. Electroluminescence spectra and brightness current measurement reveal that the phase tuning layer emits photons. Such a tandem device can increase the current efficiency by 110% and reduce the operating voltage by 1.3 V, in comparison to the conventional high contrast OLED. Measured reflection spectra validate the high contrast capability of the OLED and demonstrate experimentally an average reflectance of 5.9% in the visible range from 400 to 750 nm, which is much lower than 20.3% for the conventional high contrast OLED.

• 出版日期2012-11-22