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The hierarchical self-assembly of the charge-transfer (CT) complexes in the solid state is of paramount importance to dictate the performance of electronic devices. In this work, we describe a three-component hierarchical self-assembly approach to generate stable alternate donor–acceptor (D–A) assemblies within block copolymer microdomains by involving the supramolecular approach in self-assembly of block copolymers. So far, the assembly between a single small molecule and block copolymer was explored to obtain block copolymer supramolecules. Here we report block copolymer supramolecules composed of two small molecules (donor and acceptor) and polystyrene-block-poly­(4-vinylpyridine) (PS-b-P4VP). 1-Pyrenebutyric acid (PBA, donor) forms hydrogen bonding with P4VP and aromatic interactions with naphthalene diimide (NDI, acceptor) to generate CT complexes within the block copolymer domains in the solid state. Using FTIR, SAXS, WAXS, TEM, UV/vis spectroscopy, and photoluminescence spectroscopy measurements, we demonstrate the formation of hierarchical structures and CT complexes between PBA and NDI. Space charge limited current analysis showed the enhanced charge carrier mobility in PS-b-P4VP (PBA+NDI) supramolecules compared to that in the physical blends of PBA+NDI. The organization of donor and acceptor molecules within the block copolymer microdomains opens up new insight into the area of electronic devices because of its advantages such as solution processability, controlled formation of hierarchical assemblies, and the CT interaction in the solid state.

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The semiconductor/dielectric interface controls the performance of organic field-effect transistors (OFETs). Herein, the influence of both the molecular weight and the polarity of the solvent of a poly(methyl methacrylate) (PMMA)-based gate dielectric on the performance of pentacene OFETs is systematically investigated, by studying surface energy, surface roughness, morphology, leakage current, and capacitance of the dielectric. Various existing views on the role of the surface energy are considered while deriving a correlation. Larger pentacene grains are observed when the film is grown on high molecular weight-PMMA films cast from high dipole moment-solvent. The electrical properties of the corresponding OFETs show great improvement compared to those of OFETs fabricated with low molecular weight-PMMA film as the gate dielectric, irrespective of the solvent. The authors attribute this enhanced performance to the increased surface energy of the polymeric dielectric which turns out to be a strong function of its molecular weight and the dipole moment of the solvent. Bias-stress measurements on the OFETs confirm this correlation.

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