Solid-State Conformation, Molecular Packing, and Electrical and Optical Properties of Processable β-Methylated Sexithiophenes

Abstract

Newly synthesized sexithiophenes, di-and tetramethylated at the β-positions, are shown to be soluble and processable compounds, giving single crystals suitable for X-ray structure determination. The molecular packing was characterized in terms of crystal cohesion and short CsH‚‚‚ S and CsH‚‚‚π intermolecular distances. In particular, the dimethylated sexithiophene displayed very compressed molecular packing and a thin film field effect transistor, fabricated with this material, was characterized by high charge mobility [2 × 10 -2 cm 2 /(V s)]. The tetramethylated compound crystallizes at room temperature in two different systems and with different conformations. The conformational polymorphs, which are easily interconverted at room temperature, are characterized by different wavelengths of light emission and excitation decay rates.

Electronic structure of organic films in the first excited states determined using scanning tunneling spectroscopy: An experimental and theoretical study

“…The T6Me2 spectrum has the broad line shape typical of thiophenes, 52 centered at 410 nm, a redshift of 22 nm compared to that of the solution. 35 This peak corresponds to the 1 1 B u molecular transition, as is also the case for unsubstituted sexithiophenes. 52 The relatively narrow line shape 53 of the peaks in the pentacene absorption spectrum allows more information to be derived from the spectrum of Fig.…”

Organic Semiconductor Materials

“…described the synthesis, crystal structure, and electrical measurements on the di-and tetramethyl-substituted 6Ts. 25 Compound Mera6T was found to exhibit high mobility (0.02 crrr/V«) as an evaporated film and good solid-state order in packing. In 1999, it was found that the carrier mobility of regiochemically pure isoDH-a6T approaches 0.1 cm A problem associated with using electron-rich, thiophene-based semiconductors is their sensitivity to atmospheric doping, which diminishes the on/off ratio and alters the threshold voltage.…”

Nanopatterning Soluble Multifunctional Materials by Unconventional Wet Lithography

“…[60] They succeeded in controlling both the conformation and the supramolecular arrangement of a thiophene-based molecular material (DTT7Me) [64] by exploiting the amplification of the instability phenomena during a dewetting process. The conformational flexibility of DTT7Me, typical of several substituted oligothiophenes, [65] rendered it possible to achieve the coexistence of two regularly alternating regions on a micrometer scale, emitting light at different wavelengths (see Fig. 9).…”