Organic semiconductors (OSCs) are important active materials for the fabrication of next-generation organic-based electronics. However, the development of n-type OSCs lags behind that of p-type OSCs in terms of charge-carrier mobility and environmental stability. This is due to the absence of molecular designs that satisfy the requirements. The present study describes the design and synthesis of n-type OSCs based on challenging molecular features involving a π-electron core containing electronegative N atoms and substituents. The unique π-electron system simultaneously reinforces both electronic and structural interactions. The current n-type OSCs exhibit high electron mobilities with high reliability, atmospheric stability, and robustness against environmental and heat stresses and are superior to other existing n-type OSCs. This molecular design represents a rational strategy for the development of high-end organic-based electronics.
Variation
of aggregated structures driven by side chains is a crucial
issue in organic semiconductors (OSCs) for achieving high carrier
mobility and device durability. In this work, phenylalkyl side chains
composed of a rigid terminal phenyl group and a flexible alkyl linker
were studied based on a state-of-the-art n-type π-electron system,
3,4,9,10-benzo[de]isoquinolino[1,8-gh]quinolinetetracarboxylic diimide (BQQDI), from the viewpoints of
aggregated structures and thin-film transistors. An appropriate length
of the alkyl, i.e., propyl, linker led to stable formation of a unique
aggregated structure regardless of solution-grown single-crystal and
vacuum-deposited polycrystalline thin films likely due to cooperation
of rigid phenyl and flexible alkyl moieties. In contrast, a shorter
ethyl linker showed polymorphism in the polycrystalline film. An absence
of polymorphism did not only result in high mobility and low threshold
voltage but also show low contact resistance. Hence, this work proposes
opportunities to design n-type OSCs by introduction of both rigid
and flexible characters to the side chains.
No heavy‐atom effect: Highly fluorescent, sulfur‐ or selenium‐containing compounds were synthesized by intramolecular [4+2]‐cycloadditions between 9‐anthryl or 1‐naphthyl and alkynyl moieties (see scheme). Their fluorescence is based on a 1‐chalcogeno‐1,3‐butadiene‐conjugated system in a rigid skeleton. Some of them are also highly fluorescent in the solid state. The monoxide of Mbb‐S is more fluorescent in the solid state (ΦF=0.6) than in solution (ΦF<0.02).
Operational
stability, such as long-term ambient durability and
bias stress stability, is one of the most significant parameters in
organic thin-film transistors (OTFTs). The understanding of such stabilities
has been mainly devoted to energy levels of frontier orbitals, thin-film
morphologies, and device configuration involving gate dielectrics
and electrodes, whereas the roles of molecular and aggregated structural
features in device stability are seldom discussed. In this Letter,
we report a remarkable enhancement of operational stability, especially
bias stress, of n-channel single-crystal OTFTs derived from a replacement
of phenyl with perfluorophenyl groups in the side chain. Because of
the several-molecule-thick single-crystal nature employed for the
OTFTs, the crystal-surface properties are thought to be critical,
where the surface structure composed of perfluorophenyl moieties could
suppress interactions between environmental species and field-induced
carriers owing to increased hydrophobicity and steric protection of
π-conjugated units.
The deuteration of a diverse group of silanes: alkyl-, aryl-, alkoxy-and chlorosilanes, siloxane and silazane, under an atmosphere of dideuterium (D 2 ) was explored with ruthenium bis(dihydrogen) dihydride complexes and hydrated metal salts. Deuterium incorporation of greater than 97% for the silanes OA C H T U N G T R E N N U N G (SiMe 2 H) 2 , Et 3 SiH, (EtO) 3 SiH and Me 2 ClSiH was possible with 0.
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