A Computation-Assisted Approach to Defining the Optimal Processing Window for Meniscus-Guided Coating of Organic Semiconductors

Meniscus-guided coating (MGC) methods, such as zone casting, dip coating and solution shearing, are scalable laboratory models for large-area solution coating of functional materials for thin-film electronics. Last year, we published a model capable of predicting how due to changes in the nucleation density, a spherulitic morphology of a crystallizing molecular semiconductor crosses over to a ribbon-like structure as a function of the coating speed and the solvent’s evaporation rate [1]. The calculations explain that if coating is fast, evaporation drives the system quickly past supersaturation, giving isotropic domain structures. If coating is slow, depletion due to crystallization stretches the domains in the coating direction. Recently, we followed up on this by demonstrating with morphology simulations as well as analytical theory why if coating becomes very slow, a second structural transition takes place from a ribbon-like morphology “back” to an isotropic, domain-like structure [2]. All calculations are validated by optical microscopy on coated thin-films of the semiconductor and explain measured variations in the in-plane charge transport and OFET performance. This presentation gives a comprehensive overview of our integrated theoretical and experimental approach and methodology, leading to the design of an optimal processing window for the controlled deposition of organic semiconductors by MGC.<br/>[1] J. J. Michels, K. Zhang, P. Wucher, P. M. Beaujuge, W. Pisula, T. Marszalek, Nat. Mater. (2021), 20, 68–75.<br/>[2] O. Yildiz, Z. Wang, M. Borkowski, G. Fytas, P. W. M. Blom, J. J. Michels, W. Pisula, T. Marszalek, Adv. Funct. Mater. (2021), 2107976.