کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1665836 | 1518056 | 2013 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes](/preview/png/1665836.png)
• The matched energy level between the hole transport/emitting layer lowers voltages.
• Multiple conduction dopants were used to investigate charge generation layer.
• Two-color emitters were used to quantify the charge generation strength.
In general, organic light-emitting devices (OLEDs) need to operate at higher current density levels to ensure an ample light flux. However, stressed operation will result in poor performance and limited device lifetime. Recently, a tandem structure has been proposed as a pivotal technique to meet the stringent lighting requirements for OLED commercialization, with a research focus on decreasing the concomitant higher operation voltage. Driving two connected emission units (EMUs) in a tandem structure often requires more than twice the driving voltage for a single EMU. This study investigates bipolar host materials and their effective employment in fabricating tandem white phosphorescent OLEDs (PhOLEDs). In addition, the design of a mechanism to align the energy level between the hole transport layer/emitting layer is shown to effectively mitigate operational voltages. In sharp contrast to devices using a unipolar host material, we demonstrate that the turn-on voltage of blue PhOLEDs could be decreased from 3.8 V to 2.7 V through utilizing a bipolar host. Furthermore, applying the proposed techniques to tandem white PhOLEDs produces a luminance of 103 cd/m2 by a 10.1 V driving voltage.
Journal: Thin Solid Films - Volume 548, 2 December 2013, Pages 389–397