喷墨打印共轭高分子墨水成膜的三相线行为调控薄膜形态

Controlling of morphology and quality of inkjet printed polymer films is a main research field for their application in printed electronics. There are always some problems for inkjet printed polymer films, include low patterning resolution, non-regular structure, non-uniform thickness and coffee-ring effect. Controlling of three phase contact line in films forming process is the key to avoid the problems mentioned above. Therefore, the relationship between behavior of three phase contact line in films forming process and inks properties of conjugated polymer inks and its interaction with substrate will be researched in this project. The main research content include: (1) Relationship between droplet spreading velocity/diameter and rheology of conjugated polymer inks and its dynamic wettability will be found. (2) Method of controlling droplet coalescence degree by thermodynamics (dynamic contact angle) and kinetics (surface tension and viscosity of inks) will be developed. (3) The way to realize pinning of three phase contact line, marangoni flow and weak flow field in drying process of coalescent droplets will be found and used to eliminate coffee-ring effect and improve patterning resolution. (4) Morphology of inkjet printed polymer light-emitting films will be optimized. The effect of films morphology on performance of inkjet printed polymer light-emitting matrix display will be researched. The goal of this project is inkjet printing of polymer light-emitting pixel matrix with regular structure, uniform thickness, eliminated coffee-ring effect and high patterning resolution, which can provide core technique for printed electronics.

喷墨打印高分子薄膜的质量和形态调控是印刷电子领域的重要研究方向。打印高分子薄膜图案中通常存在尺寸精度低、结构不规整、厚度不均匀和咖啡环效应等问题。鉴于控制打印液滴成膜过程的三相线对克服以上问题的核心作用，本项目将研究液滴铺展、融合和干燥过程的三相线行为与共轭高分子墨水性质及其与基底相互作用的关系，主要研究内容包括：（1）建立液滴铺展速率和铺展直径与共轭高分子墨水的流变性质和动态润湿性关系。（2）发展液滴融合程度的热力学（动态接触角）和动力学（墨水表面张力/粘度）因素调控方法。（3）掌握墨水干燥过程中实现三相线固定、Marangoni对流和弱流动场的途径，抑制咖啡环效应并提高打印图案精度。（4）优化打印高分子发光薄膜形态，研究其对高分子发光矩阵显示器件性能的影响。本项目的目标是实现结构规整、厚度均匀、无咖啡环效应的高精度高分子发光显示像素阵列的喷墨打印加工，为印刷电子领域提供核心技术。

喷墨打印高分子发光薄膜的质量调控是印刷电子领域的重要研究方向。改善高分子发光薄膜厚度均匀性是提高器件性能并保证器件规模加工稳定性和一致性的有效手段。本项目针对喷墨打印高分子发光薄膜中存在的尺寸精度低、结构不规整、厚度不均匀和咖啡环效应等核心问题，研究墨水打印液滴的铺展和融合行为及可有效抑制喷墨打印发光薄膜去润湿及咖啡环效应，提高打印薄膜均匀性的方法及其原理，实现均匀连续发光薄膜打印和高性能发光器件制备。我们首先通过调控墨水流体性质和粘弹性，实现了单一稳定液滴的打印效果。在此基础上，调控墨水物性参数和液滴间距，使墨水铺展/融合速度相匹配，提高液滴融合对称性和均匀性。进一步通过三相线固定型主溶剂选择抑制薄膜去润湿，通过墨水粘度/挥发性匹配抑制毛细流动及调控马拉哥尼对流和弱流动场协同作用抑制咖啡环效应，提高打印薄膜图案的结构规整性。实现了大面积高质量喷墨打印图案化薄膜，并成功用于有机电致发光器件的加工，实现了打印器件性能的提高。