An Organic Metal Derived from a Selenium Analogue of Benzothienobenzothiophene

Abstract

Benzothieno[3,2‐b]benzothiophene (BTBT) is an excellent organic transistor material, and its charge‐transfer salt (BTBT)2PF6 is an organic metal that exhibits conductivity as high as 1500 S cm–1 at room temperature. Here, we report a charge‐transfer salt of the selenium analogue, benzoseleno[3,2‐b]benzoselenophene (BSBS). (BSBS)2TaF6 is a one‐dimensional metal isostructural to (BTBT)2PF6. The resistance jump temperature is reduced from 150 to 90 K, and the increase of the low‐temperature resistivity is largely diminished. However, the spin susceptibility shows an obvious drop below 50 K, which implies that the low‐temperature ground state is essentially a singlet state.

Carrier Charge Polarity in Mixed-Stack Charge-Transfer Crystals Containing Dithienobenzodithiophene

“…Among small-molecule transistor materials, various thienoacenes have been investigated as hole-transporting materials, , in which [1]­benzothieno­[3,2- b ]­[1]­benzothiophene (BTBT) derivatives are known to exhibit excellent mobility and high stability in organic transistors. − BTBT also forms charge-transfer complexes such as (BTBT) 2 XF 6 (X = P, As, Sb, and Ta), which show very high conductivity as well as metallic temperature dependence. − Tetracyanoquinodimethane (TCNQ) complexes of BTBT derivatives consist of alternating stacks of donor and acceptor molecules. − In such a case, hopping transport is supposed, where electrons transported from A to A have to overcome the donor potential. Nonetheless, single-crystal transistors of these complexes exhibit electron mobilities of 0.4 cm 2 V –1 s –1 in (C n BTBT)­(F 4 TCNQ), 0.19 cm 2 V –1 s –1 in (BTBT)­(F 4 TCNQ), and 0.097 cm 2 V –1 s –1 in (DMeO-BTBT)­(F 2 TCNQ), where C n BTBT and DMeO-BTBT are dialkyl- and dimethoxy-BTBT, respectively.…”

Charge-Transfer Complexes of Benzothienobenzothiophene with Tetracyanoquinodimethane and the n-Channel Organic Field-Effect Transistors

“…It is well-known that benzothieno­[3,2- b ]­benzothiophene (BTBT) derivatives show excellent p-channel transistor properties . The herringbone packing is related to the transistor properties, and especially the transistors of the octyl derivative, C 8 -BTBT, exhibit quite high mobility even in the solution process. , Organic CT complexes of BTBT analogs have been reported recently; the complex (BTBT) 2 XF 6 (X = P, As, Sb, and Ta) exhibits high conductivity of 4100 S cm –1 at room temperature, , and the selenium analog, benzoseleno­[3,2- b ]­benzoselenophene (BSBS), forms a similar high conducting salt, (BSBS) 2 TaF 6 , with one-dimensional columns . C n -BTBT ( n = 4, 8, and 12) form CT complexes with TCNQ derivatives, , and the single-crystal transistors attain maximum mobility of 0.4 cm 2 V –1 s –1 , although these CT complexes have mixed-stack structures.…”

Transport Properties of Molecular Conductors (BSBS)2XF6 (X = As, Sb, and Ta): Investigation of Intermolecular Transfer Integrals in the Radical-Cationic State of Benzothienobenzothiophene-Type Semiconductors

“…Crystallographic data are listed in Table , and the molecular packing is shown in Figure . The AsF 6 and SbF 6 complexes are isostructural to the TaF 6 and (BTBT) 2 XF 6 (X = P, As, Sb, and Ta) complexes. − There are four BSBS molecules and two anions per unit cell; hence, the donor-to-anion stoichiometry is 2:1. This indicates that BSBS exists in a partially oxidized state with a +0.5 e charge and forms a 3/4-filled energy band structure.…”

“…Therefore, BTBT complexes are promising candidates for organic TE materials. However, there are only six examples of such complexes in the literature. − …”