(581e) Bio-Inspired Dynamic Templates for Directing Multi-Scale Assembly of Polymer Semiconductors

Printed electronics based on solution processable semiconducting polymers have emerged as a burgeoning platform technology that promise to revolutionize the electronics manufacturing from transistors, sensors, solar cells, light-emitting diodes (LEDs), to medical devices. Unlike traditional electronic manufacturing operated at elevated temperature and high vacuum, conjugated polymers can be printed at ambient conditions on flexible substrates to produce light-weighted, bio-integrated electronics at low cost and over large areas. It is well-known that electrical properties of semiconducting polymers are highly sensitive to morphological parameters across all length scales from intermolecular ordering to macroscale alignment and can modulate device performance up to several orders of magnitude. However, high-throughput solution coatings are often operated at far from equilibrium conditions and controlling morphological parameters all at once across multiple length scales remains a key challenge. Resultantly, printed polymer thin films frequently exhibit poor ordering hindering both commercial viability of high-performance printed electronics and the understanding of charge transport mechanism in conjugated polymers.

We ascribe these non-ideal morphologies to the kinetic mismatch between slow polymer assembly and crystallization (minutes to hours) and high-speed coating (seconds) originating from the complex polymer conformational degree of freedom and weak intermolecular interactions. Substrate surface properties have profound impact on the conjugated polymer multiscale assembly and ensuing crystallization process. Inspired by biomineralization templates in living systems capable of surface reconfiguration, we introduced the concept of dynamic templating for directing crystallization-triggered multi-scale assembly of conjugated polymers. Strong polymer-substrate interactions arising from both template’s chemistry and dynamics decrease the free energy barrier to polymer heterogeneous nucleation and expedite polymer crystallization addressing the disparity in time scales of polymer assembly and high-throughput coating. Resultantly, highly ordered highly crystalline polymer thin films over large area (>1cm²) was obtained not attainable by simply varying coating conditions and substrate surface chemistry. We developed robust solution processable gel dynamic templates that effectively enhance conjugated polymer crystallization and also induce exceptional charge carrier concentration in field effect transistors, making our generic methodology a potential candidate for commercialization of printed polymer semiconductor devices.