Of Devices and Droplets: Evaporative Structuring of Solution-Processed Semiconducting Polymer Blends

Dec 1, 2016  |  4:00pm | ESB 1001
Jasper Michels
Group Leader, Department of Molecular Electronics, Max Planck Institute for Polymer Research
Abstract

Many organic and hybrid thin film electronic devices (e.g. memory diodes, solar cells, light emitting diodes, transistors, capacitors) typically contain a functional layer based on a blend comprising multiple polymeric or small-molecular species whose properties cooperatively give rise to a specific function. Depending on the desired functionality, phase separation during film processing is either encouraged or suppressed. As usually at least one blend component is polymeric, mutual segmental repulsion readily overcomes the entropic driving force to form stable mixtures. For this reason, it is often observed that during solution-casting droplet-like demixed structures emerge due to liquid-liquid demixing, which may or may not be desirable. This presentation will focus on the role of liquid-liquid demixing in thin film electronics by demonstrating how local phase composition and characteristic morphological features affect (opto-)electronic performance. Calculations based on mixing thermodynamics as well as results from dynamic phase field simulations will be placed in direct context with electronic processes such as charge injection, recombination and trapping. As the community heavily relies on controlling morphology development during solution-processing, I would in the second part of the presentation like to share novel insight concerning the influence of solvent evaporation on spinodal decomposition. We have recently shown how both the early and late stages of demixing are strongly affected by the continuous drift in composition imparted by evaporation, and why significant deviation from the “classical” laws governing structure formation and domain growth is observed.

BiographyJasper Michels studied Chemistry at the University of Amsterdam, where he obtained his MSc degree in Organic Chemistry under the supervision of Prof. W. N. Speckamp and Prof. H. Hiemstra. He did his PhD in supramolecular chemistry at the University of Twente at the group of Prof. D. N. Reinhoudt and Prof. J. Huskens. After his graduation he held a post-doctoral research position for two years at the group of Prof. H. L. Anderson at Oxford University. His work at Oxford was consecutively sponsored by the English Engineering and Physical Sciences Research Council (EPSRC), and the European Union’s Marie Curie Fellowship Association. He worked on the synthesis and photo-physical characterization of conjugated luminescent poly(rotaxanes). During his time at Oxford he cooperated with the research groups of Prof. R. H. Friend (University of Cambrigde) and Prof. F. Cacialli (University College, London). Upon returning to the Netherlands he worked as a Senior Scientists on upscaling of thin film device technology at TNO and Holst Centre in Eindhoven. Two years ago he took up a position as Group Leader at the Department of Molecular Electronics of the Max Planck Institute for Polymer Research (Mainz, Germany). His current research activities range from conducting polymer synthesis to device physics. He has a special focus on modeling and simulation of the phase dynamics of semiconducting polymer blends in solution.

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