Metallic-type Transport in Polymers: Establishing Materials Design Criteria and Predicting Structure/property Interrelations
The research addresses fundamental questions of how charge-carrier coherence length and transport properties correlate with specific structural features in doped organic materials. Optical spectroscopies (absorption, photoinduced absorption, photoluminescence, photoluminescence excitation, and two-dimensional coherent excitation spectra), along with thermal analysis and X-ray diffraction data, will be used to construct a database on doped polymers, oligomers and small molecules, utilizing a variety of dopants. Key spectral observables will be modeled with existing theoretical tools at LANL, using first-principle calculations with atomistic approaches, nonadiabatic molecular dynamics simulations, and parameterized Holstein lattice models to simulate quantum dynamics of charges, focusing on spatial coherence lengths of charge carriers in materials. Nonlinear spectroscopies will be used to refine the details of the quantum dynamics models, as they provide details of not only population but also temporal and spatial coherence dynamics. In particular, these measurements can isolate the homogeneous excitation linewidth from the total spectral lineshape, thereby providing a very sensitive probe of spatial coherence, limited by the quantum dynamics that lead to carrier localization. The PIs also plan to release the DMREF Polymeric Semiconductor Toolbox and Database as open source and build a user community around the language by ensuring that interested researchers are able to contribute to the DMREF Polymeric Semiconductor Toolbox and Database codebase. This will allow a wider growth of the project. This aspect is of special interest to the software cluster in the Office of Advanced Cyberinfrastructure, which has provided co-funding for this award.