2,7-Diphenyl[1]benzoselenopheno[3,2-b][1]benzoselenophene as a stable organic semiconductor for a high-performance field-effect transistor

[1]Benzoselenopheno[3,2-b][1]benzoselenophene (BSBS) and its 2,7-diphenyl derivative (DPh-BSBS) were readily synthesized from diphenylacetylene and bis(biphenyl-4-yl)acetylene, respectively, with a newly developed straightforward selenocyclization protocol. In contrast to the parent BSBS that has poor film-forming properties, the diphenyl derivative DPh-BSBS formed a good thin film on the Si/SiO₂ substrate by vapor deposition. X-ray diffraction examination revealed that this film consists of highly ordered molecules that are nearly perpendicular to the substrate, making it suitable for use in the fabrication of organic field-effect transistors (OFETs). When fabricated at different substrate temperatures (room temperature, 60 °C, and 100 °C) in a "top-contact" configuration, all the DPh-BSBS-based OFET devices exhibited excellent p-channel field-effect properties with hole mobilities >0.1 cm² V^-1 s^-1 and current on/off ratios of ∼10⁶. This high performance was essentially maintained over 3000 continuous scans between V_g = +20 and -100 V and reproduced even after storage under ambient laboratory conditions for at least one year.