Liu Shihao, Zhang Xiang, Zhang Letian, Xie Wenfa
State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun, 130012, People's Republic of China.
Sci Rep. 2016 Nov 22;6:37042. doi: 10.1038/srep37042.
Ultrasonic spray coating process (USCP) with high material -utilization, low manufacture costs and compatibility to streamline production has been attractive in researches on photoelectric devices. However, surface tension exists in the solvent is still a huge obstacle to realize smooth organic film for organic light emitting devices (OLEDs) by USCP. Here, high quality polymer anode buffer layer and small molecular emitting layer are successfully realized through USCP by introducing extra-low surface tension diluent and surface tension control method. The introduction of low surface tension methyl alcohol is beneficial to the formation of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) films and brings obvious phase separation and improved conductivity to PEDOT:PSS film. Besides, a surface tension control method, in which new stable tension equilibrium is built at the border of wetting layer, is proposed to eliminate the effect of surface tension during the solvent evaporation stage of ultrasonic spray coating the film consists of 9,9-Spirobifluoren-2-yl-diphenyl-phosphine oxide doped with 10 wt% tris [2-(p -tolyl) pyridine] iridium (III). A smooth and homogenous small molecular emitting layer without wrinkles is successfully realized. The effectiveness of the ultrasonic spray coating polymer anode buffer layer and small molecular emitting layer are also proved by introducing them in OLEDs.
具有高材料利用率、低制造成本且与流水线生产兼容的超声喷雾涂层工艺（USCP）在光电器件研究中颇具吸引力。然而，溶剂中存在的表面张力仍是通过USCP实现用于有机发光器件（OLED）的光滑有机膜的巨大障碍。在此，通过引入超低表面张力稀释剂和表面张力控制方法，利用USCP成功实现了高质量的聚合物阳极缓冲层和小分子发射层。引入低表面张力的甲醇有利于聚（3,4-乙撑二氧噻吩）聚苯乙烯磺酸盐（PEDOT:PSS）膜的形成，并使PEDOT:PSS膜产生明显的相分离且提高了导电性。此外，还提出了一种表面张力控制方法，即在超声喷雾涂覆由掺杂10 wt%三[2-（对甲苯基）吡啶]铱（III）的9,9-螺二芴-2-基-二苯基氧化膦组成的膜的溶剂蒸发阶段，在润湿层边界建立新的稳定张力平衡，以消除表面张力的影响。成功实现了无皱纹的光滑且均匀的小分子发射层。将聚合物阳极缓冲层和小分子发射层引入OLED中也证明了超声喷雾涂层的有效性。
