Thin Film Microstructure of a Solution Processable Pyrene-Based Organic Semiconductor

Abstract

Semiconducting 6,7,15,16-tetrakis(dodecylthio)quinoxalino[2′,3′:9,10]phenanthro[4,5-abc]phenazine (TQPP-12) has been synthesized as a candidate solution-processable semiconductor for organic electronics applications. We characterize the microstructure of TQPP-12 in films using a combination of polarized photon absorption spectroscopies (X-ray, vis, and infrared), X-ray diffraction, and scanning probe techniques. This characterization strategy allowed for the determination of molecular orientation and packing style within thin films of this complex molecule. The TQPP-12 molecules are arranged within layers, and the aromatic cores are separated from the alkane side chains. Both the core long axes and side chains are highly tilted with respect to surface normal, and the conjugated planes of the core are cofacially packed.