Gravure printed organic thin film transistors: Study on the ink printability improvement

Ink Formulation for Printed Organic Electronics: Investigating Effects of Aggregation on Structure and Rheology of Functional Inks Based on Conjugated Polymers in Mixed Solvents

“…For instance, if the polymer aggregation induced by the solvent composition influences the viscosity behavior of the ink during the printing process, it could affect the formation of drops in inkjet printing or cell filling in gravure printing. [ 13,17,58 ] Of course, the influence of the very high shear rates associated with inkjet printing (>10 6 s −1 ) is outside the scope of the present experiment. Nevertheless, the observed aggregation can have an influence on the characteristics of the deposited layer and ultimately on the optoelectronic properties of the device and should therefore be considered when designing a functional ink.…”

“…Moreover, it enables the adjustment of viscoelastic properties towards the rheological window of the chosen printing technique. [ 16,17 ] The control over the aforementioned parameters is crucial for alleviating undesired effects such as coffee‐stain formation or viscous fingering, which are detrimental to the film topography and device functionality. [ 18,19 ]…”

“…Moreover, it enables the adjustment of viscoelastic properties towards the rheological window of the chosen printing technique. [16,17] The control over the aforementioned parameters is crucial for alleviating undesired effects such as coffee-stain formation or viscous fingering, which are detrimental to the film topography and device functionality. [18,19] Yet, the theoretical prediction of the viscosity of multicomponent solutions of OSC polymers is not straightforward and, therefore, the adjustment of their rheological properties usually requires multiple trial-and-error iterations.…”

Mapping the Volume Transfer of Graphene-Based Inks with the Gravure Printing Process: Influence of Rheology and Printing Parameters

“…In order to reach that resolution in patterning with graphene inks by means of the gravure printing process, it is of paramount importance to understand the role that the rheology of the ink plays in the physics underneath each of the four main steps involved: the first step is the filling in which the gravure cells are overfilled by the ink; the second step is the wiping , where a doctor blade removes the excess ink; the third step is the transferring , where the substrate contacts the ink contained in the gravure cells and then the ink is picked out and transferred to the substrate; and the last step is the levelling , in which the individual droplets deposited onto the substrate are spread by gravity to create a continuous pattern [ 15 ]. Very recently, Wu et al [ 16 ] numerically analyzed the effect of shear thinning on the liquid filling problem involving a stationary trapezoidal cavity and a horizontal plate above the cavity.…”

“…It is important to note that their experimental studies were performed with relatively large gravure cells, and wetting/de-wetting may be a critical phenomenon in determining pick out at low stretch rates under gravitational forces. The final levelling of the ink depends strongly on its rheological properties; thus, a Newtonian-like ink would tend to achieve a highly uniform film over large areas, while a pseudoplastic behavior would allow for highly scaled features [ 15 ].…”