New Semiconducting Multi-branched Conjugated Molecules Bearing 3,4-Ethylenedioxythiophene-based Thiophenyl Moieties for Organic Field Effect Transistor

Abstract

New pi-conjugated multi-branched molecules were synthesized through the Homer-Emmons reaction using alkyl-substituted, 3,4-ethylenedioxythiophene-based, thiophenyl aldehydes and octaethyl benzene-1,2,4,5-tetrayltetrakis(methylene) tetraphosphonate as the core unit; these molecules have all been fully characterized. The two multi-branched conjugated molecules exhibited excellent solubility in common organic solvents and good self-film forming properties. The semiconducting properties of these multi-branched molecules were also evaluated in organic field-effect transistors (OFET). With octyltrichlorosilane (OTS) treatment of the surface of the SiO2 gate insulator, two of the crystalline conjugated molecules, 7 and 8, exhibited carrier mobilities as high as 2.4 (+/-0.5) x 10(-3) and 1.3 (+/-0.5) x 10(-3) cm(2)V(-1)s(-1) respectively. The mobility enhancement of OFET by light irradiation (lambda = 436 nm) supported the promising photo-controlled switching behavior for the drain current of the device.