浸渍提拉法制备连续、高度有序有机半导体薄膜:弯月面角的关键作用

Continuous and highly ordered organic semiconductor thin films via dip-coating:the critical role of meniscus angle

浸渍提拉法是一种低成本、大面积、高效制备有机半导体薄膜的技术.针对该技术中提拉速度、溶剂类型、溶液浓度等参数的研究报道已很多.但由于忽略了提拉过程中溶液-衬底相互作用这个关键因素,提拉得到的沉积物绝大多数为带状或树枝状晶体,覆盖率较低.本文提出用弯月面角(MA)来量化浸渍提拉过程中溶液与衬底的实时相互作用的强弱.通过对衬底进行适当的表面处理,可以调节MA值,从而可以获得厘米级、连续、高度有序的有机半导体薄膜,并构建了有机场效应晶体管(OFETs),研究了连续薄膜的电荷输运特性.最大(平均)空穴迁移率可达11.9(5.1)cm2V-1s-1.统计显示连续薄膜的平均迁移率比带状晶体高82%,表明所制备的薄膜具有高结晶度.该工作揭示了浸渍提拉过程中动态溶液-衬底相互作用在薄膜沉积过程中扮演的关键角色,给出了衡量二者之间相互作用强弱的量化指标,为浸渍提拉法制备大面积、连续、高度有序的有机半导体薄膜的研究及其在各种光电器件领域的应用提供了理论和技术支撑.

Dip-coating is a low-cost,high-throughput technique for the deposition of organic semiconductors over large area on various substrates.Tremendous studies have been done and many parameters such as withdrawal speed,solvent type and solution concentration have been investigated.However,most of the depositions were ribbons or dendritic crystals with low coverage of the substrate due to the ignorance of the critical role of dynamic solution-substrate interactions during dip-coating.In this study,meniscus angle(MA)was proposed to quantify the real-time in-situ solutionsubstrate interactions during dip-coating.By proper surface treatment of the substrate,the value of MA can be tuned and centimeter-sized,continuous and highly ordered organic semiconductor thin films were achieved.The charge transport properties of the continuous thin films were investigated by the construction of organic field-effect transistors.Maximum(average)hole mobility up to 11.9(5.1)cm2V-1s-1was obtained.The average mobility was 82%higher than that of ribbon crystals,indicating the high crystallinity of the thin films.Our work reveals the critical role of dynamic solutionsubstrate interactions during dip-coating.The ability to produce large-area,continuous and highly ordered organic semiconductor thin films by dip-coating could revival the old technique for the application in various optoelectronics.