Estimation of Polaron Delocalization Lengths in Conjugated Organic Polymers

Organic conjugated polymers have been pivotal in the development of organic electronics in applications such as in organic field effect transistors and photovoltaics. In these applications, the electronic structures of the polymers change by the gain or loss of charge. In this work, the visualization of charge delocalization in oligomeric and polymeric systems by range-separated density functional theory calculations reveals an efficient method of determining the polymer limit and polaron delocalization lengths of conjugated systems. Methods of displaying these data and the important computational details of the calculations are explored. These calculations provide researchers information about intrachain charge transport, donor-acceptor characteristics, and a method of validating that the computational model structures are indeed representative of the polymer and not just small molecules. Contributions from differing co-monomers to the polymer properties can be assessed through plotting the charge distributions along the polymer backbone. Visualization of polaron (de)localization can guide future polymer design, e.g., by placement of solubilizing chains to aid interchain interactions at polymer sections bearing greater polaron localization, or by minimizing charge accumulation at potentially reactive monomer units.