HMNTL INVITED LECTURE:
Charge Transport in Doped Conjugated Polymers for Organic Electronics
Zlatan Aksamija
Materials Science and Engineering, University of Utah
Abstract – Organic electronic materials, specifically conjugated polymers, are a cost-effective and environmentally friendly alternative to inorganics. However, conjugated polymers are semiconducting materials that do not possess intrinsic free carriers, which means they must be doped to increase the number of free carriers and boost conductivity. Dopant-carrier interactions dramatically alter the energetics of the electronic states available for transport as well as the dynamics of free carriers. In this seminar, I will discuss our results based on a comprehensive transport model that accounts for modification of the electronic density of states (DOS) in the presence of dopants together with phonon-assisted carrier hopping simulation through those states. The hopping transport simulation is based on numerically solving the Pauli Master equation to extract both electrical conductivity and the thermoelectric Seebeck coefficient at each doping concentration across a broad range. We validate our calculations against measurements on iodine-doped P3HT. In our work, we also introduce carrier screening in the Debye-Hückel formalism to capture the competing roles of screening and dopant-induced disorder on transport. We show that screening of Coulomb interactions by free carriers plays a key role in transport at high doping concentrations. Our work paves the way towards organic electronics with better electrical properties, with applications in wearables, flexible electronics, OPVs, and organic thermoelectric energy conversion.
Bio – Zlatan is currently an Associate Professor in Materials Science and Engineering at the University of Utah, where he joined in 2022 after having spent over 8 years in the Electrical and Computer Engineering Department at the University of Massachusetts in Amherst. Before that, Zlatan held the NSF CI TraCS postdoctoral fellowship at the University of Wisconsin-Madison, where his research focused on thermoelectric energy conversion and nanoscale heat transfer. He received his B.S, M.S. and Ph.D. in Electrical Engineering from the University of Illinois at Urbana/Champaign. Currently, Zlatan leads the NanoEnergy lab at Utah, where he is developing a deeper understanding electronic transport and thermal management in 2D materials, van der Waals heterostructures, and organic electronics with the goal of improving their electro-thermal performance as well as exploiting nanostructures for more efficient thermoelectric conversion of waste heat energy into useful electricity. Zlatan also serves as the Career Mentoring Fellow with the American Physical Society.
