Abstract Using printed organic materials to fabricate organic light emitting diodes (OLEDs) is a low-cost process and one of the most innovative deposition technologies. Nozzle jet printing is a facile method with the advantages of high speed and large area fabrication. However, the printing process leaves residual solvent in the deposited organic films. How that remaining solvent affects the performance of the OLEDs, and the fundamental mechanism of that effect, is still unclear. In this study, we investigated the effect of residual solvent in a jet printed phosphorescent emissive layer. Gas chromatography-mass spectrography (GC–MS) was used to measure the amount of residual solvent, which was dependent on the film drying environment. The printed phosphorescent films exhibited weak intersystem crossing and decreased coupling between the vibrational states of the tris[2-(p-tolyl)pyridine]iridium(III) (Ir(mppy)3) in measurements of ultraviolet–visible absorption (UV–vis Abs), photoluminescence (PL), and electroluminescence (EL). The deterioration of the photophysical characteristics of the phosphorescence was attributed to the polaronic effect of the residual solvent molecules. The dipoles of the solvent molecules influenced the orbitals of surrounding organic molecules, and those perturbations induced nonradiative relaxation of the excitons. There was no shift in the peaks, but the intensities of the photophysical measurements decreased, indicating that the deterioration in phosphorescence was not chemical degradation. Finally, when the amount of residual solvent increased, the current density and the efficiency of the fabricated OLED decreased. The residual solvent also resulted in efficiency roll-off at high luminance in the devices.

中文翻译：

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印刷磷光发光薄膜中残留溶剂的影响作为有机发光二极管效率受限的根源

摘要 使用印刷有机材料制造有机发光二极管 (OLED) 是一种低成本工艺，也是最具创新性的沉积技术之一。喷嘴喷射印刷是一种简便的方法，具有高速和大面积制造的优点。然而，印刷过程会在沉积的有机薄膜中留下残留溶剂。残留的溶剂如何影响 OLED 的性能，以及这种影响的基本机制，仍不清楚。在这项研究中，我们研究了喷射印刷磷光发光层中残留溶剂的影响。气相色谱-质谱 (GC-MS) 用于测量残留溶剂的量，这取决于薄膜干燥环境。印刷的磷光膜在紫外-可见光吸收（​​UV-vis）测量中表现出弱的系统间交叉和三[2-（对甲苯基）吡啶]铱（III）（Ir（mppy）3）的振动态之间的耦合降低Abs)、光致发光 (PL) 和电致发光 (EL)。磷光光物理特性的恶化归因于残留溶剂分子的极化效应。溶剂分子的偶极子影响周围有机分子的轨道，这些扰动会引起激子的非辐射弛豫。峰没有移动，但光物理测量的强度降低，表明磷光的恶化不是化学降解。最后，当残留溶剂量增加时，制造的OLED的电流密度和效率降低。残留溶剂还导致器件在高亮度下的效率下降。