Thiophene-Phenylene and Thiophene-Thiazole Oligomeric Semiconductors with High Field-Effect Transistor On/Off Ratios

Abstract

A series of thiophene-containing oligomers that are less electron rich than alpha-6T were synthesized, and the thin film morphologies and field-effect transistor characteristics of the oligomers were evaluated. Phenyl and thiazole rings were included in many of the oligomers, and a new synthesis of perfluoroalkylmethyl-terminated oligomers was developed. Desirably low off currents were associated with calculated highest occupied molecular orbital energies above ca. 5.0 eV relative to vacuum. Some of the oligomers displayed mobilities above 0.01 cm 2 (Vs) -1 , but there was no correlation of mobility with calculated orbital energies and some compounds with seemingly continuous morphologies had low mobilities nonetheless. One compound, 1,4-bis(5′-hexyl-2,2′-bithiophen-5-yl)benzene, showed promising behavior as a solution-deposited semiconductor, with mobility up to 0.02 cm 2 (Vs) -1 and an on/off ratio up to 20 000.

n‐Type Building Blocks for Organic Electronics: A Homologous Family of Fluorocarbon‐Substituted Thiophene Oligomers with High Carrier Mobility

“…tive. [27] Indeed, it is known that strong fluoroalkyl substituent r-withdrawing inductive effects (-I) are attenuated by CH 2 insertion (cf. r Hammet values of benzoic and phenylacetic acids), [28] and the core HOMO/LUMO energies presumably fall within a range where neither electrons nor holes find sufficient stabilization to create a majority conductive channel.…”

Improved Crystal‐Growth and Emission Gain‐Narrowing of Thiophene/Phenylene Co‐Oligomers

“…[3,4] The family of these oligomer materials is characterized by the well-defined molecular axes and exhibits various interesting electric transport and light emission features on the basis of the disposition of their axes in thin films and crystals. [5][6][7][8] In particular, the thiophene/phenylene co-oligomers have a variety of extension of π-conjugation along the backbone. The conjugation extension can be tuned by changing the total number of the thiophenes and phenylenes and their mutual arrangement in the molecules.…”

Molecular and Supramolecular Architectures of Organic Semiconductors for Field‐Effect Transistor Devices and Sensors: A Synthetic Chemical Perspective

“…These compounds exhibit remarkable air stability combined with high mobility (0.1 cm 2 V -1 s -1 ) and high on/off current ratio (10 5 Interestingly, introduction of unsubstituted 1,4-phenylene or terminal phenyl units in linear oligothiophene structures, like in compounds 74-76 reported in Scheme 23, produces oligomers with excellent properties including high solubility and environmental stability. [102] The solubilizing effect of terminal hexyl chains is more substantial for these compounds than for any other thiophene backbones.…”