New semiconducting multi-branched conjugated molecules bearing 3,4-ethylene- dioxythiophene-based thiophenyl moieties for organic field effect transistor

New φ-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 Si02 gate insulator, two of the crystalline conjugated molecules, 7 and 8, exhibited carrier mobilities as high as 2.4 (± 0.5)*10^-3 and 1.3 (± 0.5)xl0 ^-3 cm² V^-1s^-1, respectively. The mobility enhancement of OFET by light irradiation (γ = 436 ran) supported the promising photo-controlled switching behavior for the drain current of the device.