Functional Polymers for Widespread Energy Applications

My current research as postdoctoral researcher at UC Santa Barbara (since May 2013) focuses on structure-property relationships of semiconducting polymers for organic field-effect transistors (OFETs) and organic thermoelectrics.  One of the research directions under the advisement of Prof. Ed Kramer has been the structural characterization of aligned semiconducting polymers where the measured mobility has been greater than 20 cm²/Vs.  A combination X-ray scattering and electron microscopy techniques provides evidence for exceptional alignment of the polymer chains. This allows for an efficient intrachain charge transport between source/drain contacts, thus resulting in the measured high mobility.  Another research direction under the advisement of Prof. Michael Chabinyc has focused on how various processing conditions effect the thermoelectric properties (Seebeck coefficient, electronic conductivity, and thermal conductivity) of highly doped semiconducting polymers.          

My Ph.D. research at UC Berkeley under the advisement of Prof. Nitash Balsara focused on the synthesis and characterization of simultaneous electronic and ionic conducting block copolymers (P3HT-block-PEO) for lithium battery electrodes.  Block copolymers can self-assemble and form co-continuous nanoscale domains, which are necessary for enabling redox reactions of the active material (LiFePO₄).  In addition, the block copolymer serves as a binder to hold the redox-active material particles together. This simplifies the electrode design as one material serve both binding and charge transport functions.  The application of this material in a lithium battery with LiFePO₄ showed specific capacity reaching the theoretical limit and with minimal capacity fade after ten cycles, thus demonstrating feasibility of P3HT-b-PEO as a conductive binder material.  Furthermore, the ability of the conductive binder to switch between electronically conducting and insulating states in the positive electrode provides an unprecedented route for automatic overdischarge protection within the battery.  This is in stark contrast to traditional lithium ion batteries where external electronics is used to provide overdischarge protection.

My Ph.D. and postdoctoral research provides a unique background in electrochemistry and polymer physics.  My proposed research will build upon my diverse Ph.D. and postdoctoral research background.  In particular, the proposed research topics focus on polymer-based thermal energy harvesting. The fundamental science underlying the application of conducting polymers for thermal energy harvesting focuses on the transport of charge carriers in the form of ions or electrons for electrical conduction and phonons with respect to thermal conduction.  A fundamental understanding between these transport pathways and polymer morphology is crucial in the development of high efficiency polymer-based thermal energy harvesting devices. Furthermore, the work in the Patel Research Lab will be inherently collaborative spanning synthetic chemistry, soft-material science, polymer physics, and electrochemistry.