Uniform Quantum Dot Film with Well-Defined Edges by A Helical Fibrous Liquid Bridge: Toward High-Performance Light-Emitting Diode
摘要
Uniform quantum dot (QD) films, especially those with well-defined edges, are crucial for high-performance quantum dot light-emitting diode (QLED) devices. However, current solution strategies have suffered from either the inhomogeneity or irregular edges aroused by the uncontrollable fluid dynamics during liquid transfer onto and/or dewetting on the target substrate. Here, we developed a helical fibrous liquid bridge approach to transfer liquid homogeneously across the entire printing area, enabling a uniform QD film with well-defined edges over an area up to 32 cm2. The helical fiber, with a thread width of approximately 120 μm, facilitates periodic anchoring of the liquid bridge during the whole liquid transfer process, leading to a homogeneous liquid film. Worth noting is that the as-formed quasi-steady meniscus at the liquid bridge edge helps suppress variation in edge curvature, whereby the pinning sites of the tri-phase contact line are liable to move along a defined linear edge. By this virtue, we demonstrated a high-performance red QLED with a peak luminance of 2.4 × 105 cd/m2 and a peak EQE of 20.8%. The result offers an alternative facile approach for making uniform QD films with well-defined edges, which facilitates further device integration.
Graphical Abstract