The morphological effects of regioregular poly(3-hexylthiophene) (P3HT) on its p-doping kinetics with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) in solution are studied using optical absorption spectroscopy and stopped-flow technique. Two morphological forms, solubilized (s-P3HT) and nanowhiskers (nw-P3HT), are investigated. Both P3HT solubilized and aggregated solutions show similar characteristic near-IR absorption bands for integer charge transfer products with F4-TCNQ. Kinetic analysis on p-doping of s-P3HT with F4-TCNQ indicates that the doping reaction proceeds with a single reaction mechanism that is first order in s-P3HT. The doping kinetics of P3HT aggregate solution shows two distinctive reaction mechanisms. The slow mechanism has a reaction rate constant similar to that of solubilized P3HT solution, so it likely results from s-P3HT components that are present in the aggregate solution. The fast one is assigned to the nw-P3HT component, probably due to more efficient charge delocalization in the aggregated P3HT nanostructures. Additionally, the kinetic trends of the p-doping reactions are better fitted with the consideration of a Gaussian-like distribution of reactivities from P3HT, matching the complexity of polymeric systems originating from molecular weight and morphology variations. This study highlights the importance of considering different morphological forms of conjugated polymers on their charge-transfer reaction kinetics. The knowledge gained here should be fundamentally and practically important for future chemical doping applications in organic electronic device fabrications.

An eumelanin-inspired core derived from the natural product, vanillin (vanilla bean extract) was utilized for the synthesis of eumelanin-inspired small molecules and polymer via Sonogashira cross coupling. The materials demonstrate that the methyl 4,7-dibromo-5,6-dimethoxy-N-methyl-1H-indole-2-carboxylate core can serve as a new building block for organic semiconductors.

Non-doped and chemically p-doped poly(3-hexylthiophene) (P3HT) nanowires are investigated by optical spectroscopy and atomic force microscopy (AFM) to reveal the effects of doping on their aggregation processes and nanoscale morphologies. The AFM studies on the non-doped P3HT nanowires formed in the early aggregation stage demonstrate that P3HT molecules will probably go through either packing of high-aspect ratio multi-chain/single-chain aggregates or packing of solubilized individual chains depending on experimental conditions. High-resolution AFM images also show the connecting segments between ordered domains of P3HT. For pdoping of P3HT in the solution phase, the addition of 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (F 4 -TCNQ), a p-dopant, will greatly accelerate the aggregation rate of 1D P3HT nanostructures. The doped P3HT nanowires are comprised of linearly connected domains that are 40− 60 nm wide and 5−10 nm high. Compared with the non-doped P3HT nanowires, doped nanowires show smoother edges and less protruding segments, likely due to a different aggregation mechanism. Furthermore, the doped nanowires tend to agglomerate into disordered bundles and clusters because of the presence of F 4 -TCNQ counterions and complexity resulting from Coulomb interactions and other doping-induced growth defects.