Organic Electronic Materials Laboratory, Department of Information Display, Kyung Hee University , Seoul 02447, Republic of Korea.
Department of Physics and Institute of Basic Sciences, Kyung Hee University , Seoul 02447, Republic of Korea.
ACS Appl Mater Interfaces. 2017 Jul 12;9(27):22748-22756. doi: 10.1021/acsami.7b03557. Epub 2017 Jun 28.
We investigated interfacial mixing of solution-processed organic light-emitting devices (OLEDs) using impedance spectroscopy (IS) and ultraviolet photoelectron spectroscopy (UPS) and its impact on device performance. We focused on interfacial mixing between a solution-processed cross-linkable hole transport layer (XM) and an emitting layer (EML), formed either by solution processing or vacuum evaporation. The results of IS and UPS clearly indicated that extensive interfacial mixing was unavoidable, even after the XM was cross-linked to make it insoluble and rinsed to remove residual soluble species, if the subsequent EML was solution processed. In addition, we also demonstrated that interfacial mixing indeed increased hole current density in corresponding hole only device (HOD). In fact, the hole injection efficiency could be an order of magnitude better when the EML was solution processed rather than vacuum evaporated. We investigated such behavior to find the desirable process condition of solution-processed OLEDs.
我们使用阻抗谱（IS）和紫外光电子能谱（UPS）研究了溶液处理有机发光器件（OLED）的界面混合及其对器件性能的影响。我们专注于溶液处理的可交联空穴传输层（XM）和发射层（EML）之间的界面混合，这些层可以通过溶液处理或真空蒸发形成。IS 和 UPS 的结果清楚地表明，即使在 XM 交联使其不溶并用冲洗去除残留的可溶性物质之后，如果随后的 EML 通过溶液处理形成，也不可避免地会发生广泛的界面混合。此外，我们还证明了界面混合确实会增加相应的空穴仅器件（HOD）中的空穴电流密度。事实上，当 EML 通过溶液处理而不是真空蒸镀形成时，空穴注入效率可以提高一个数量级。我们研究了这种行为，以找到溶液处理 OLED 的理想处理条件。
