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Recently, studies of 2D organic layered materials with unique electronic properties have generated considerable interest in the research community. However, the development of organic materials with functional electrical transport properties is still needed. Here, a 2D fused aromatic network (FAN) structure with a C5 N basal plane stoichiometry is designed and synthesized, and thin films are cast from C5 N solution onto silicon dioxide substrates. Then field-effect transistors are fabricated using C5 N thin flakes as the active layer in a bottom-gate top-contact configuration to characterize their electrical properties. The C5 N thin flakes, isolated by polydimethylsiloxane stamping, exhibit ambipolar charge transport and extraordinarily high electron (996 cm2 V-1 s-1 ) and hole (501 cm2 V-1 s-1 ) mobilities, surpassing the performance of most pristine organic materials without doping. These results demonstrate their vast potential for applications in thin-film optoelectronic devices.

Multiple-patterned nanostructures prepared by synergistically combining block-copolymer lithography with nano-imprinting lithography have been used as back reflectors for enhancing light absorption in organic optoelectronic devices. The multiple-patterned electrodes have significantly boosted the performance of organic photovoltaics and photo-transistors, owed to the highly effective light scattering and plasmonic effects, extending the range of their practical applications.

Control over the morphology and crystallinity of metal halide perovskite materials is of key importance to enable high-performance optoelectronics. Here, a simple yet effective template-free self-assembly synthesis of perovskite granular wires with ultrahigh photodetectivity (3.17 × 1015 Jones) is reported. The 1D self-assembly of perovskite grains is driven by differences in the surface interaction energies of the granular facets. The superb photodetecting performance originates from extremely low dark current engendered by energetic barriers featuring unique band-edge modulation along the long axis of wire. Flexible photodetector arrays, fabricated by selectively placing perovskite granular wires onto pre-patterned electrode arrays on a transparent polymer substrate, show independently addressable photonic signal mapping with remarkably high detectivity, photoconductive gain, and responsivity. The "self-assembled nanograin engineering" strategy developed in this study provides a viable method for the development of high-performance perovskite photodetectors and can be extended to other integrated optoelectronic systems.

Large-scale FET-type graphene micropattern (GM) nano-biohybrid-based immunosensor (GMNS) is fabricated in a controlled fashion to detect human immunodeficiency virus 2 antibody. Flexible GMNS shows a highly sensitive response and excellent mechanical bendability. The flexible GMNS in fluidic systems also has a stable response. This is the first experimental demonstration of a large-scale flexible fluidic FET-type immunoassay based on GM nano-biohybrids.

p-type semiconductors have been studied extensively, research on n-channel semiconducting materials still lags behind these developments. The availability of high-performance n-type materials, in which the majority charge carriers are electrons, is desirable for the fabrication of p-n junctions and complementary circuits. Apart from high electron mobilities, practically useful n-type semiconductors should possess a sufficiently high electron affinity to allow for efficient electron injection from common metal electrodes into these materials. [1d] A major drawback of many compounds described in the literature is the poor stability in devices operated under ambient conditions. The introduction of fluorinated alkyl groups has been shown to lead to improved air-stabilities in various instances, and it has been argued that this stabilization originates in self-segregation of closely-packed fluorocarbon chains that prevents the diffusion of air and moisture into the channel region. [1a,b] Perylene tetracarboxylic acid bisimides (PBIs) are among the most promising and versatile candidates for (opto)electronic applications, because their electronic and optical properties as well as their solid–state packing can be tuned in a wide range. [2] The solid state packing and concomitant properties of PBIs can be tailored by introduction of appropriate substituents either in the imide position or by core substitution in the bay region. Substitution in the 1, 6, 7, and 12 positions of the PBI backbone enforces a considerable twisting of the perylene skeleton out of planarity. [2] The effect of this structural modification on the electrical and charge transport properties of these semiconductors is not yet well understood, though. Whereas intermolecular coupling might be reduced in core-twisted PBIs, this modification might, on the other hand, help to prevent the formation of dimeric pairs that have been envisaged as potential electron traps. [3] To elucidate the effect of successive bay substitution, we describe here the synthesis and a comparison of two novel fluoro-substituted PBI derivatives, PBI-F2 and PBI-F4 (Scheme 1), that combine fluoroalkyl groups in imide position with two or four fluorine atoms in the bay region. [4]

This work was supported by the Brain-Korea 21 Program (Korea Ministry of Education), and the Korea Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center.

This work was supported by the Brain-Korea 21 Program of the Korean Ministry of Education and the Hyperstructured Organic Materials Research Center supported by the Korean Science and Engineering foundation. We thank Dr. S.-H. Yoon for discussions and acknowledge JEOL Co. for assistance with HRTEM.

Recent interest in flexible electronics has led to a paradigm shift in consumer electronics, and the emergent development of stretchable and wearable electronics is opening a new spectrum of ubiquitous applications for electronics. Organic electronic materials, such as π-conjugated small molecules and polymers, are highly suitable for use in low-cost wearable electronic devices, and their charge-carrier mobilities have now exceeded that of amorphous silicon. However, their commercialization is minimal, mainly because of weaknesses in terms of operational stability, long-term stability under ambient conditions, and chemical stability related to fabrication processes. Recently, however, many attempts have been made to overcome such instabilities of organic electronic materials. Here, an overview is provided of the strategies developed for environmentally robust organic electronics to overcome the detrimental effects of various critical factors such as oxygen, water, chemicals, heat, and light. Additionally, molecular design approaches to π-conjugated small molecules and polymers that are highly stable under ambient and harsh conditions are explored; such materials will circumvent the need for encapsulation and provide a greater degree of freedom using simple solution-based device-fabrication techniques. Applications that are made possible through these strategies are highlighted.

Chiral supramolecular nanostructures with optoelectronic functions are expected to play a central role in many scientific and technological fields but their practical use remains in its infancy. Here, this paper reports photoconductive chiral organic semiconductors (OSCs) based on perylene diimides with the highest electron mobility among the chiral OSCs and investigates the structure and optoelectronic properties of their homochiral and heterochiral supramolecular assemblies from bottom-up self-assembly. Owing to the well-ordered supramolecular packing, the homochiral nanomaterials exhibit superior charge transport with significantly higher photoresponsivity and dissymmetry factor compared with those of their thin film and monomeric equivalents, which enables highly selective detection of circularly polarized light, for the first time, in visible spectral range. Interestingly, the heterochiral nanostructures assembled from co-self-assembly of racemic mixtures show extraordinary chiral self-discrimination phenomenon, where opposite enantiomeric molecules are packed alternately into heterochiral architectures, leading to completely different optoelectrical performances. In addition, the crystal structures of homochiral and heterochiral nanostructures have first been studied by ab initio X-ray powder diffraction analysis. These findings give insights into the structure-chiroptical property relationships of chiral supramolecular self-assemblies and demonstrate the feasibility of supramolecular chirality for high-performance chiroptical sensing.