Control of Polar/Antipolar Layered Organic Semiconductors by the Odd-Even Effect of Alkyl Chain.

Some rodlike organic molecules exhibit exceptionally high layered crystallinity when composed of a link between π-conjugated backbone (head) and alkyl chain (tail). These molecules are aligned side-by-side unidirectionally to form self-organized polar monomolecular layers, providing promising 2D materials and devices. However, their interlayer stacking arrangements have never been tunable, preventing the unidirectional arrangements of molecules in whole crystals.

Ambipolar Nickel Dithiolene Complex Semiconductors: From One- to Two-Dimensional Electronic Structures Based upon Alkoxy Chain Lengths.

Air-stable single-component ambipolar organic semiconductors that conduct both holes and electrons are highly desired but have been rarely realized. Neutral nickel bis(dithiolene) complexes are promising candidates that fulfill the stringent electronic requirements of shallow HOMO levels and deep LUMO levels, which can reduce the carrier injection barrier to overcome the work function of gold electrodes and ensure air stability. However, most nickel bis(dithiolene) analogs that have been characterized as ambipolar semiconductors have twisted molecular structures that hinder the effective intermolecular interactions required for carrier conduction.

Regioisomeric control of layered crystallinity in solution-processable organic semiconductors.

The construction and control of 2D layered molecular packing motifs with functionally substituted π-electron cores are crucial for developing organic electronic materials and devices. We investigated a regioisomeric structure-property relationship in high-performance and solution-processable layered organic semiconductors based on -octyl-substituted benzothieno[3,2-]naphtho[2,3-]thiophene (-C8-BTNT). We demonstrated that an isomorphous layered herringbone packing motif is obtainable in a series of four positional isomers of -C8-BTNTs whose π-electron core is substituted by an octyl chain at one of the four most peripheral positions with roughly keeping the rod-like molecular shape.

Meniscus-controlled printing of single-crystal interfaces showing extremely sharp switching transistor operation.

Meniscus, a curvature of droplet surface around solids, takes critical roles in solution-based thin-film processing. Extension of meniscus shape, and eventual uniform film growth, is strictly limited on highly lyophobic surfaces, although such surface should considerably improve switching characteristics. Here, we demonstrate a technique to control the solution meniscus, allowing to manufacture single-crystalline organic semiconductor (OSC) films on the highest lyophobic amorphous perfluoropolymer, Cytop.

New π-extended catecholato complexes of Pt(ii) and Pd(ii) containing a benzothienobenzothiophene (BTBT) moiety: synthesis, electrochemical behavior and charge transfer properties.

Benzothienobenzothiophene (BTBT) and derivatives have received increasing attention as organic field-effect transistor materials and molecular conductors. This report presents the first synthesis of metal complexes involving a BTBT moiety, which was achieved by complexation of 2,2'-bipyridyl complexes of Pt(ii) and Pd(ii) with dihydroxy-substituted BTBT (1) as a new π-extended catecholato ligand (BuBpy = 4,4'-di-tert-butyl-2,2'-dipyridyl). The resulting complexes M(BuBpy)(OBTBT) (M = Pt (3Pt) and Pd (3Pd)) were characterized by UV-vis spectroscopy, density functional theory (DFT) calculations, and cyclic voltammetry.

Benzothienobenzothiophene-Based Molecular Conductors: High Conductivity, Large Thermoelectric Power Factor, and One-Dimensional Instability.

On the basis of an excellent transistor material, [1]benzothieno[3,2-b][1]benzothiophene (BTBT), a series of highly conductive organic metals with the composition of (BTBT)2XF6 (X = P, As, Sb, and Ta) are prepared and the structural and physical properties are investigated. The room-temperature conductivity amounts to 4100 S cm(-1) in the AsF6 salt, corresponding to the drift mobility of 16 cm(2) V(-1) s(-1). Owing to the high conductivity, this salt shows a thermoelectric power factor of 55-88 μW K(-2) m(-1), which is a large value when this compound is regarded as an organic thermoelectric material.

A Single-Component Conductor Based on a Radical Gold Dithiolene Complex with Alkyl-Substituted Thiophene-2,3-dithiolate Ligand.

Alkyl-substituted thiophene-2,3-dithiolate ligands are prepared through a Thio-Claisen rearrangement of 4,5-bis(propargylthio)-1,3-dithiole-2-thione derivatives. The two novel dithiolate ligands, namely, 4,5-dimethyl-thiophene-2,3-dithiolate (α-Me2tpdt) and 4-ethyl-5-methyl-thiophene-2,3-dithiolate (α-EtMetpdt), are engaged in anionic Au(III) square planar complexes formulated as [Au(α-Me2tpdt)2](-) and [Au(α-EtMetpdt)2](-), isolated as Ph4P(+) salts. Monoelectronic oxidation gives the neutral radical complexes [Au(α-Me2tpdt)2](•) and [Au(α-EtMetpdt)2](•).

A highly conducting organic metal derived from an organic-transistor material: benzothienobenzothiophene.

BTBT ([1]benzothieno[3,2-b][1]benzothiophene) is an organic semiconductor that realizes high mobility in organic transistors. Here we report that the charge-transfer (CT) salt, (BTBT)2PF6, shows a high room-temperature conductivity of 1500 S cm(-1). This compound exhibits a resistivity jump around 150 K, but when it is covered with Apiezon N grease the resistivity jump is suppressed, and the metallic conductivity is maintained down to 60 K.