The fabrication of a high-quality POLED (Polymeric Organic Light Emitting Diode) display requires the deposition of identical, uniform fluid films into a large number of shallow recessed regions that form a regular array of pixels on a display backplane. We determine the protocols required to achieve continuous liquid coverage of the entire pixel area for the case where equally-spaced fluid droplets are sequentially printed along a straight line within a stadium-shaped pixel, and explore how these protocols depend on the wetting properties of the pixel surface. Our investigation uses a combination of experiments and numerical modelling, based on the assumption of fluid redistribution via capillary spreading according to a Cox-Voinov law. We show that the model is able to predict quantitatively the evolution of the liquid deposited in a pixel and provides a computationally inexpensive design tool to determine efficient printing strategies that account for uncertainties arising from imperfect substrate preparation or printhead dysfunction.
@article{arxiv.1906.07824,
title = {POLED displays: Robust printing of pixels},
author = {P. Kant and A. L. Hazel and M. Dowling and A. B. Thompson and A. Juel},
journal= {arXiv preprint arXiv:1906.07824},
year = {2020}
}