Synthesis of thiophene/phenylene co‐oligomers. V. Functionalization at molecular terminals toward optoelectronic device applications

Abstract

We report the synthesis of various thiophene/phenylene co‐oligomers with a total number of thiophene and benzene (phenylene) rings of 5 and 6 with various terminal groups. Those terminal groups have been chosen from among alkyl groups, methoxy groups, trifluoromethyl groups, and cyano groups. The molecular backbone of these compounds comprises phenyl‐ or biphenylyl‐capped thiophene (or oligothiophene) or an alternating co‐oligomer. The synthesis is based on either the Suzuki coupling reaction or the Negishi coupling reaction. These reaction schemes enabled us to obtain the target compounds in high quality. In particular, the latter coupling method turned out to produce the compounds at a high yield. The terminal groups are expected to produce various functionalities based upon their electron donating character (alkyl groups and methoxy groups) or electron withdrawing character (trifluoromethyl groups and cyano groups). Additionally some of these groups bring about enhanced solubility. This will lead to the production of a diversity of modified compounds of thiophene/phenylene co‐oligomers. To give an example that demonstrates usefulness of the target compounds, we present optoelectronic data that are associated with their device applications.

Thin-film and single-crystal transistors based on a trifluoromethyl-substituted alternating (thiophene/phenylene)-co-oligomer

“…The synthetic root was slightly different as per a report by Katagiri et al [24]. We confirmed its structure by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectroscopy (Perspective Biosystems, Voyager-DE PRO) and 1 H NMR (Bruker AVANCE 400)).…”

“…Note that Hotta et 4 al. recently reported the synthesis of the same material [24], formation of its crystal [25], the crystal structure and its field-effect transistors (FETs) [26]. However, Hotta et al reported that AC-CF3 single-crystal FETs showed n-type behavior and that the electron mobility of the FETs ranged from 1.6 to 3.9  10 −2 cm 2 V −1 s −1 .…”

Organic Light‐Emitting Field‐Effect Transistors Operated by Alternating‐Current Gate Voltages

“…The carrier mobility of the BP1T thin-film device is estimated at $10 À3 cm 2 V À1 s À1 for the normal p-channel DC operation. [15] We show in Figure 1b a schematic structure of the bottom-gate OLEFET device equipped with interdigitated electrodes of channel length L. (constant channel width 8 cm). The equivalent circuit is schematically shown in Figure 1c.…”

Organic light-emitting diodes based on layered films of thiophene/phenylene co-oligomers

“…We chose thiophene/phenylene co-oligomers (TPCOs), a newly occurring class of organic semiconductors [7,8]. The TPCOs are a series of compounds where thiophene and phenylene rings are hybridized at the molecular level with their various mutual arrangements.…”