Inkjet printing is considered to be the most promising means of pixelated, large-scale processing of organic light-emitting diode (OLED) panels. However, the uniformity of the films printed in the banks and the device performance are major challenges in printed OLEDs. Herein, we propose controlling the uniformity of the film printed in the banks through Marangoni flow and contact line sliding. To verify our idea, three kinds of poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) ink with different Marangoni flow were used, i.e., toluene (TOL)/cyclohexylbenzene (CHB), TOL/butyl benzoate (BB) and TOL/1-chloronaphthalene (1-CN) inks. The inks were printed into the bank (dyed by rhodamine B). The motion of the contact line and the liquid surface profile changes at different times were revealed by the change in the luminescent intensity of F8BT ink in the bank (recorded by laser scanning confocal microscopy) since the intensity of rhodamine B in the bank is unchanged. For the TOL/CHB ink, the contact line can slide downward along the vertical direction of the bank during the drying process since the surface tension difference between TOL and the co-solvent and the relative value of the Marangoni flow (Δγ/η) reach a suitable value. This led to the surface profile of the liquid film remaining horizontal. Thus, a dried film with higher uniformity is obtained. However, for TOL/BB and TOL/1-CN inks, the contact line is pinned on the bank at some stage during the drying process. Thus, the final profile exhibited mount shape and ring shape, leading to poor uniformity of the dried films. The printed OLED device with TOL/CHB ink has better film uniformity than the other two inks, showing the best performance with a maximum luminance of 11 508.8 cd m⁻², current efficiency of 4.7 cd A⁻¹ and an EQE of 1.36%.

中文翻译：

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通过马兰戈尼流动和接触线滑动提高河岸中喷墨印刷聚合物薄膜的均匀性

喷墨印刷被认为是有机发光二极管（OLED）面板像素化大规模加工的最有前途的手段。然而，银行印刷薄膜的均匀性和器件性能是印刷 OLED 的主要挑战。在此，我们建议通过马兰戈尼流动和接触线滑动来控制河岸上印刷薄膜的均匀性。为了验证我们的想法，使用了三种具有不同Marangoni流动性的聚(9,9-二辛基芴-替代-苯并噻二唑)(F8BT)墨水，即甲苯(TOL)/环己基苯(CHB)、TOL/苯甲酸丁酯(BB)和 TOL/1-氯萘 (1-CN) 油墨。将墨水打印到银行中（由罗丹明 B 染色）。由于河岸中罗丹明 B 的强度不变，通过河岸中 F8BT 墨水的发光强度的变化（激光扫描共焦显微镜记录）揭示了不同时间接触线的运动和液体表面轮廓的变化。对于TOL/CHB油墨，由于TOL和共溶剂之间的表面张力差以及Marangoni流的相对值(Δ γ / η )，在干燥过程中接触线可以沿着堤岸的垂直方向向下滑动。达到合适的值。这导致液膜的表面轮廓保持水平。由此，能够得到均匀性更高的干燥膜。然而，对于 TOL/BB 和 TOL/1-CN 油墨，接触线在干燥过程中的某个阶段固定在岸上。因此，最终的轮廓呈现出安装形状和环形，导致干燥膜的均匀性差。采用TOL/CHB墨水印刷的OLED器件比其他两种墨水具有更好的薄膜均匀性，表现出最好的性能，最大亮度为11 508.8 cd m ^-2，电流效率为4.7 cd A ^-1，EQE为1.36%。