Book Description

Conjugated polymers, representing a new generation of semiconductors, have attracted tremendous attention in the past few decades attributed to their conspicuous properties, such as flexibility, light weight, stretchability and solution processability, which is promising for manufacturing low-cost, large-area, and flexible electronic devices. Moreover, performance of semiconducting behaviors could be readily modulated via manipulating chemical structure and morphology. Organic field-effect transistors (OFETs) are the elemental components in electrical circuits. Although considerable materials were synthesized and investigated, there are still numerous approaches either in novel materials or morphological control which have not been explored. Therefore, in this research, five different strategies were proposed to attain conjugated polymer-based higher performance materials for OFETs, including novel pigment monomers, polymerization method and morphological manipulation by hydrogen bonding and conjugated cross-linking. In Part I, a blue/violet pigment, benzimidazolone-dioxazine-based molecule, was employed into donor−acceptor based conjugated polymers. Through the molecular modulation, the donors with matched size for donor-acceptor packing in the conjugated polymer thin films were uncovered, revealing refined charge carrier mobilities owing to the extended conjugated length of benzimidazolone-dioxazine structure. Part II discloses the diketopyrrolopyrrole(DPP)-quaterthiophene-based donor-acceptor copolymers with latent hydrogen bonding isoindigo-bithiophene to amend the charge transport in amorphous phase via hydrogen bonding-induced aggregation after thermal treatment. Part III applied the robust hydrogen bonding interaction to directly patterning conjugated polymer thin films and their OFETs with exceptional balance of mobilities and resolution of patterns, which is compatible with conventional photolithography in integrated circuit. Part IV introduces a newfangled method to obtain conjugated polymers with controlled molecular weight in the solid state, consisting of conventional anionic-polymerization and topochemical reaction. Moreover, this strategy could be further utilized to prepare the high-performance semiconducting material, graphene nanoribbons. Part V coalesced the concepts of Part II and IV to construct conjugated cross-linking between polymer backbones through topochemical reactions on diketopyrrolopyrrole(DPP)-quaterthiophene-based copolymers with latent cross-linkable diacetylene-bithiophene moieties, ameliorating the charge transport without demolishing the favorable packing of donor-acceptor conjugated polymers.