Charge carrier dynamics in single conjugated polymer chain

Ming Lei (a) and Jason McNeill (a)

Department of Chemistry

Conjugated polymers possess a high density of delocalized π electrons and exhibit high absorption coefficients with electronic band gaps ranging from UV to near-infrared. However, the disordered or semicrystalline structure of the polymer leads to a complex energy landscape for charge carriers, characterized by trapping or dispersive transport. Therefore, a deeper understanding of the relationship between nanoscale structure and charge transport properties is vital for investigating and improving conjugated polymer-based device performance. In our lab, previous studies found that the fluorescence centroid displacement can be used to estimate the position of a single charge carrier in a conjugated polymer nanoparticle. The position can be recorded over time, showing the trajectory of the charge carrier. Furthermore, the fluorescence spectrum of the region within 1-3 nm of the polaron can be obtained, yielding a detailed map of the energy landscape. Previously, this charge carrier tracking technique was applied to conjugated polymer nanoparticles containing dozens or hundreds of polymer chains. In this work, technique will be modified and applied to single isolated conjugated polymer chain of PFBT (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′,3}-thiadiazole) to obtain a more detailed chain segment level picture of charge transport and the energy landscape of conjugated polymers.