Abstract

Polymer semiconductors typically are p-conjugated macromolecule. First-generation materials are well-studied and well-understood. They are flexible-chain polymers, leading to heterogeneous microstructures comprised of molecularly disordered (“amorphous”) and ordered regions (crystallites/aggregates) as in commodity plastics such as polyethylene, polypropylene, and polyesters. More modern macromolecular semiconductors are, in contrast, comprised of rigid backbones, requiring elaborate side-chain substitutions to render them processable. Because of the backbone rigidity, polymer semiconductor chains do not entangle, supporting a “liquid-crystalline”-like behavior and low long-range coherence. However, this difference is rarely discussed in literature, and classical polymer physics views, developed for flexible-chain polymers, are applied to rationalize the behavior of next-generation materials. Here, we disucss on the example of next-generation semiconductors that they are ribbon-like i.e., “sanidic”. We show that fast calorimetry, enabling measurements with high sensitivity because of ultra-fast scan rates (5,000 °C/s), is a highly useful tool to gain understanding of this polymer class, including structural factors across multiple length-scales that affect charge and mass transport, side-chain softening transitions;  and minute changes in mass or heat capacity indicating chemical or structural degradation. Favorable interactions between components in plastic solar cell donor:acceptor blends that render the devices stretchable may also be identified. Knowledge gained can be applied to gain insights in non-conjugated materials, such as commodity polymers, inorganic-organic hybrid materials, poly(oxathianethione) derivatives, and beyond. Collectively, our presentation will highlight the power of thermal analysis to understand polymeric species, beyond the identification of melting and glass transitions, only towards better detailed understanding of macromolecules.

Biography

Natalie Stingelin is a Full Professor at the Georgia Institute of Technology and the Chair of the School of Materials Science & Engineering. She held prior positions at Imperial College London, UK, at Queen Mary University of London, UK; the Philips Research Laboratories in Eindhoven, The Netherlands; the Cavendish Laboratories, University of Cambridge, UK; and the Swiss Federal Institute of Technology (ETH) Zürich, Switzerland. She is the Director of Georgia Tech’s Center of Organic Electronics and Photonics, and was elected a 2023 Member of the European Academy of Sciences (EurASc); a 2021 Fellow of the U.S. National Academy of Inventors (NAI); a 2019 Fellow of the Materials Research Society (MRS); and a 2012 Fellow of the Royal Society of Chemistry (RSC). Her research interests encompass the broad area of functional polymer materials, polymer physics, organic electronics & photonics, and bioelectronics.