Leveraging the Semiconducting Nature of Conjugated Polymers

Shrayesh N. Patel

Conjugated semiconducting polymers are highly attractive for various organic electronic and energy storage and conversion applications due to tunable electronic properties, solution processibility, and mechanical flexibility. Due to advances in molecular design and improved processing techniques, the charge carrier mobility of semiconducting polymers in thin-film field-effect transistors are now approaching and exceeding amorphous silicon (> 1 cm2V-1s-1). For the first part of the talk, I will report on the structural characterization of a macroscopically aligned semiconducting polymer thin-film for field-effect transistors. This characterization reveals key design principles describing what limits and enhances charge transport in recent high mobility semiconducting polymers. Furthermore, the discussion will be extended to chemically doped semiconducting polymers where the interplay between local and long range order strongly govern the charge transport properties. For final part of the talk, I will present my work on conducting copolymers for lithium battery electrodes. A new electrode design was developed using a diblock copolymer consisting of semiconducting poly(3-hexylthiophene) (P3HT) for electronic transport and poly(ethylene oxide) (PEO) and LiTFSI mixture for lithium ion transport. This copolymer serves both as a binder and as an electronic and ionic charge transport medium essential for enabling redox reactions. By taking advantage of the semiconducting nature of P3HT, we can uniquely control the electronic charge carrier mobility in the electrode as function of potential.

Dr. Shrayesh Patel is currently a postdoctoral research scientist at the University of California, Santa Barbara in the Materials Research Laboratory. His research expertise resides at the intersections of polymer science, organic electronic materials, and electrochemistry. Under the advisement of Prof. Michael Chabinyc, Dr. Patel's postdoctoral research has focused on the structure-property relationships of high mobility semiconducting polymers for transistors and thermoelectrics. He received his Ph.D. at the University of California, Berkeley in Chemical Engineering under the advisement of Prof. Nitash Balsara. Dr. Patel's dissertation topic was on simultaneous electronic and ionic conducting block copolymer for lithium battery electrodes. His Ph.D research was selected by AIChE as an Emerging Area in Polymer Science and Engineering and also part of the cover story for the May 2013 issue of Chemical & Engineering News. Dr. Patel received his B.S. degree in Chemical and Biomolecular Engineering at the Georgia Institute of Technology.