Improving the Thermal Stability of Top-Emitting Organic Light-Emitting Diodes by Modification of the Anode Interface
Improving the Thermal Stability of Top-Emitting Organic Light-Emitting Diodes by Modification of the Anode Interface
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DOI：
10.1002/adom.202001642
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发表时间：
2020-11-20
影响因子：
9
通讯作者：
Gather, Malte C.
中科院分区：
文献类型：
--
作者：
Deng, Yali;Keum, Changmin;Gather, Malte C.
顶发射有机发光二极管（oled）对许多应用都很感兴趣，特别是对于具有高填充因子的显示器。为了最大限度地提高效率和亮度，使用了空穴传输层（p-HTL）的分子p掺杂和高反射阳极接触，例如，由银制成。原子层沉积（ALD）对于OLED薄膜封装具有吸引力，但通常要求最低工艺温度为80℃。本文报道，在80℃的ALD封装过程中，p-HTL和顶部发射OLED的银阳极之间的界面会降解，导致OLED电流和亮度降低四倍以上。为了了解器件退化的潜在机制，研究了单电荷载流子器件在退火前后的性能。对p-HTLs的光谱研究表明，降解是由于扩散的银离子与p型分子掺杂剂之间的相互作用。为了提高界面的稳定性，在阳极/有机界面处插入超薄MoO3缓冲层或双层html。两种方法都能有效抑制降解。这项工作显示了在不牺牲器件性能的情况下使用ALD成功封装顶发射oled的途径。
Top-emitting organic light-emitting diodes (OLEDs) are of interest for numerous applications, in particular for displays with high fill factors. To maximize efficiency and luminance, molecular p-doping of the hole transport layer (p-HTL) and a highly reflective anode contact, for example, made from silver, are used. Atomic layer deposition (ALD) is attractive for thin film encapsulation of OLEDs but generally requires a minimum process temperature of 80 degrees C. Here it is reported that the interface between the p-HTL and the silver anode of top-emitting OLEDs degrades during an 80 degrees C ALD encapsulation process, causing an over fourfold reduction in OLED current and luminance. To understand the underlying mechanism of device degradation, single charge carrier devices are investigated before and after annealing. A spectroscopic study of p-HTLs indicates that degradation is due to the interaction between diffusing silver ions and the p-type molecular dopant. To improve the stability of the interface, either an ultrathin MoO3 buffer layer or a bilayer HTL is inserted at the anode/organic interface. Both approaches effectively suppress degradation. This work shows a route to successful encapsulation of top-emitting OLEDs using ALD without sacrificing device performance.