Syntheses, Solid State Structures, and Electrical Properties of Oxadiazole-Based Oligomers with Perfluorinated Endgroups

Abstract

A series of four new oligomers with oxadiazole rings and perfluorinated endgroups was synthesized, utilizing ring closure and coupling reaction procedures that we developed to be compatible with this family of compounds. Three shorter oligomers (three and four rings) crystallize readily and show rigid well-defined structures with close π interactions as determined by X-ray crystallography and thus are a suitable basis for further development as organic semiconductors. Reduction potentials (E 1/2) are at or slightly more negative than –1.1 V versus Ag/AgCl. The longest of the oligomers, with a terthiophene core, showed hole mobility in a field-effect transistor of 0.002 cm2/Vs and a threshold voltage well into accumulation. On the basis of electrochemical redox potentials, we expect that elaboration of this oligomer motif with further electron-withdrawing groups will ultimately lead to n-channel organic semiconductors.

Fluorinating π‐Extended Molecular Acceptors Yields Highly Connected Crystal Structures and Low Reorganization Energies for Efficient Solar Cells

“…Note that it was necessary to spin coat ITN‐F4 active layers from CHCl 3 rather than CB due to the low solubility of ITN‐F4 in CB, presumably reflecting the high crystallinity and strong intermolecular forces imparted by fluorination. [ 31,32,74,75 ] This behavior contrasts ITN‐C9, which has sufficient CB solubility (>10 mg mL −1 ) for OSC fabrication. ITzN‐F4 devices achieve optimal PCE (10.0%) when the active layer is spun cast from CB:DIO (99:1).…”

“…Furthermore, π‐extension and fluorination are well‐established methods to tune the properties of other types of organic semiconductors. [ 14,25,27,30–32 ]…”

Thin-Film Organic Electronic Devices

“…Fluoro-substitution remains a common theme among most of these compounds. Carbonyl functional groups are also effective in lowering the energies of injected electrons, whereas some other functional groups such as nitro and oxadiazole seem to be less beneficial (132).…”

The synthesis and optical properties of novel triphenylamine containing 1,3,4-oxadiazole derivatives

“…The 1,3,4-oxadiazole derivatives have been widely studied as materials in electroluminescent (EL) devices due to their electron deficiency, high thermal and oxidative stability [6][7][8][9][10][11]. Furthermore, oxadiazole-based oligomers with electron-accepting end moieties have also been applied in organic field-effect transistors (OFETs) [12,13]. In recent years, many 1,3,4-oxadiazole derivatives have been widely used as electrontransporting materials.…”