The Role of Molecular Structure and Conformation in Polymer Electronics

ABSTRACT Conjugated polymers have unique material properties that make them promising for a wide range of applications. The potential lies in the virtually infinite possibilities for creating new materials for specific applications by simply chemically tuning the molecular structure. Conjugated polymers can attain electrical properties comparable with noncrystalline inorganic semiconductors; however, the complex chemical and structural properties of conjugated polymers are nontrivial and resemble those of biomacromolecules. Therefore, molecular conformation and interactions play an important role in the functionality of these material systems. Properties at the molecular scale, mesoscopic scale in thin film, and device scale are fundamentally entangled, and understanding these correlations is crucial for developing highperformance polymerbased electronics. In this chapter structure–function relationships in polymerbased electronics are unravelled. In the first section, charge transport in polymer films is explored by examining the interplay between molecular ordering and electrical transport in a model system, the organic fieldeffect transistor (OFET) In the second section, the bulk heterojunction (BHJ) polymer:fullerene solar cell is introduced, and the relationships between molecular conformation, mesoscopic ordering and the optoelectronic properties of the solar cell are demonstrated. Efficiency limiting factors for BHJ are then discussed. Novel strategies for improving device performance are explored Finally, to fully illustrate the application potential of structure–function relationships in conjugated polymers, a molecularly selective polymer layer for the regulation of biomolecules in physiological media is demonstrated.