Elsa Reichmanis, Georgia Institute of Technology
Towards Robust Semiconducting Polymer Inks for Flexible Electronics
Written by Bharati Neelamraju
Organic semiconductors make flexible devices aiming toward stretchable materials a possibility. These materials can be designed synthetically to increase charge transport in devices. Elsa Reichmanis’s group uses poly-3-hexylthiophene to measure unipolar and ambipolar charge transport in organic field-effect devices via blade coating. They compared different monomer units – manipulate energy levels of resulting polymers – which changes charge transport characteristics. They observed a huge variation in mobility values of a given polymer with the same processing conditions and now tried to understand why this was happening. The researchers looked at morphology of the same polymer processed under the same conditions but still had very different atomic force microscopy (AFM) images. So how do you get reproducible results with such morphological variations on films processed the same way? How do we streamline the protocol better? Reichmanis points out how machine learning and data science could help us streamline this protocol by building a database from existing literature. Her group uses polarized microscopy, small-angle x-ray scattering, and UV-VIS spectroscopy to characterize microstructure at varying length scales of the polymer. Another project her group has been working on is transferring the known polymer knowledge onto stretchable electronics for which they use blends of PDMS and P3HT and create a ternary phase diagram with the solvent to guide design criteria for devices. She then points out that the solvents used to process most organic semiconductors are toxic and then leaves the audience to think about greener alternatives.