Influence of the Cooling Rate in Annealing Post-Treatment on Small Molecule with Siloxane Side Chains for Solution-Processed Organic Field-Effect Transistors

In this study, a donor-acceptor-type small molecule possessing a narrow bandgap with siloxane-terminated side chains, namely, S-LBG, was synthesized and characterized to be used as a semiconducting layer in organic field -effect transistors (OFETs). The diketopyrrolopyrrole (DPP)-based small molecule contains silaindacenodithio-phene as an electron-donor core and 2-(1,1-dicyanomethylene)rhodanine as an electron-accepting end group. S-LBG films show highly crystalline structures after thermal annealing treatment owing to the strong intermo-lecular interactions between its siloxane side chains; furthermore, a smooth-surface film with a large poly-crystalline grain size can be fabricated by controlling the cooling rate after annealing. Solution-processed OFETs using cooled S-LBG films at a rate of 1 degrees C/min and exhibits a high hole mobility of 0.102 cm2 V-1 s-1 with a pi-pi stacking distance of 0.659 nm.