Synthesis, properties and FET characteristics of oxygen-based heterocycle dimers 9,9′-bi(benzo[b]naphtha[2,1-d]furan)

• 9,9′-bi(benzo[b]naphtha[2,1-d]furan) (9-BBR) has enhanced the stability in air.
• OFET devices of 9-BBR with HMDS-treated substrates possess stable characteristics.
• Crystallinity and large grains are observed in thin films of 9-BBR at Tsub = 100 °C.

We have successfully synthesized and characterized newly synthesized oxygen-heterocyclic and π-conjugated dimers, 9,9′-bi(benzo[b]naphtha[2,1-d]furan) (9-BBR), as a potential semiconductor material with good environmental stability for organic field-effect transistor (OFET) devices. As expected from DFT calculations, spectroscopic analyses allow us to confirm the compound has lower highest occupied molecular orbital (HOMO) energy level and larger HOMO–lowest unoccupied molecular orbital (LUMO) gap than those of pentacene. Absorption spectra of 9-BBR in an air-saturated solution remain unchanged, indicating substantial environmental stability; in fact, the mobility values of 9-BBR-based OFET devices are stable even in the presence of air. Maximum field-effect mobilities up to 10−2 cm2 V−1 s−1 are obtained by 9-BBR-based OFETs with hexamethyldisilazane (HMDS)-treated substrates at Tsub = 100 °C. X-ray diffraction and atomic force microscopy allow us to conclude that better characteristics of 9-BBR-based OFETs prepared at high Tsub are attributed to good crystallinity and large-sized grain morphology in the thin films.

The two BR monomers of Molecule I each stacked with a BR monomer of adjacent Molecules II and III along the c-axis direction, separated by an interplanar spacing of 3.50 Å.Figure optionsDownload as PowerPoint slide