Temperature-Dependent Dynamics of PolyalkylthiopheneConjugated Polymers: A Combined Neutron Scattering and SimulationStudy.

Thedynamics of conjugated polymers are known to influence the performanceof optoelectronic devices. Polyalkylthiophenes are a widely studiedclass of conjugated polymers, which exhibit a glass transition aroundroom temperature and consequently are sensitive to temperature variations.We studied the dynamics of two polyalkylthiophenes of different sidechain lengths (hexyl and octyl) as a function of temperature, by comparingtheir quasi-elastic neutron scattering (QENS) with molecular dynamicssimulations (MD). We found a good agreement between the simulatedand experimental data within the explored time window (of ∼4ns), demonstrating that the force fields used in MD simulations areappropriate and that the QENS technique can be used as a validationof such force fields. Using MD allows us to identify and to assigncontributions to the QENS signal from different parts of the polymersand to determine the activation energies of the different motions. [ABSTRACT FROM AUTHOR]