Modeling the Drying of Ink-Jet-Printed Structures and Experimental Verification

Abstract

This article presents a numerical model that was developed for the drying of ink-jet-printed polymer solutions after filling the pixels in a polymer LED display. The model extends earlier work presented in the literature while still maintaining a practical approach in limiting the number of input parameters needed. Despite some rigorous assumptions, the model is in fair agreement with experimental data from a pre-pilot ink-jet printing line. Comparison inside a single pixel is shown, as well as a general trend in which the amount of polymer that is transported out of the central part of the pixel decreases with the rate of viscosity increase as a function of polymer concentration. Moreover, the effect of a varying solute diffusion coefficient is studied.

Characterization of Inkjet-Printed Silver Patterns for Application to Printed Circuit Board (PCB)

“…Also, inkjet-printed patterns often produce a coffee ring effect or line bulges due to the differential evaporation rates between the center and edges, droplet spacing, surface wettability, and hydrodynamic instability. To obtain uniform and reliable patterns without the coffee ring effect and line bulges, many researchers have proposed various methods, including controlling nano-particle size, stabilizing nanoparticle dispersion, controlling ink solvent properties, changing droplet spacing, heating substrates, altering surface wettabilities and mixing several solvents having different properties [5][6][7][8].…”

The Spreading of Inkjet‐Printed Droplets with Varying Polymer Molar Mass on a Dry Solid Substrate

“…When using the technique of inkjet printing, for example for the application of OLEDs, this effect should be minimized for correct device functionality. [29,33] However, much research has been conducted to prevent the coffee ring effect, for example by applying an increased substrate temperature, in order to stimulate solvent evaporation, which subsequently minimizes line or film bleeding, [34,35] and by combining a high and low boiling solvent, which reduces the high evaporation rate at a liquid feature's edge. [36] Furthermore, the replenishing flow of solute can be counter balanced by an opposite marangoni flow.…”

Thin, binary liquid droplets, containing polymer: an investigation of the parameters controlling film shape

“…The model considers an axisymmetric droplet, in a cylindrical coordinate system (radius r, height h, azimuth θ), such that velocity and gradients in the azimuthal direction are negligible (v θ = 0, ∂/∂θ = 0). As can be seen in figure 1, the horizontal length scale is the droplet radius, R, and the vertical length scale is the initial droplet height, H. An extension to droplets with a non-circular cross-section, as in van Dam & Kuerten (2008), could be an interesting topic for future work on P-OLED displays.…”