Structural Polymorphism and Thin Film Transistor Behavior in the Fullerene Framework Molecule 5,6;11,12-di-o-Phenylenetetracene

• Published in: Angewandte Chemie International Edition 2016-05, Vol.55 (20), p.6041-6046
• Main Authors: Wombacher, Tobias, Gassmann, Andrea, Foro, Sabine, von Seggern, Heinz, Schneider, Jörg J.
• Format: Article
• Language: English
• Subjects: Density functional theory; Electron transport; Face; Field effect transistors; Film thickness; fullerene; Fullerenes; fused-ring systems; Hole mobility; hydrocarbons; Molecular chains; Molecular structure; organic field effect transistor; polycycles; Polymorphism; Semiconductor devices; Thin films; Transistors
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201601517

The molecular structure of the hydrocarbon 5,6;11,12‐di‐o‐phenylenetetracene (DOPT), its material characterization and evaluation of electronic properties is reported for the first time. A single‐crystal X‐ray study reveals two different motifs of intramolecular overlap with herringbone‐type arrangement displaying either face‐to‐edge or co‐facial face‐to‐face packing depicting intensive π–π interactions. Density functional theory (DFT) calculations underpin that a favorable electronic transport mechanism occurs by a charge hopping process due to a π‐bond overlap in the DOPT polymorph with co‐facial arene orientation. The performance of polycrystalline DOPT films as active organic semiconducting layer in a state‐of‐the‐art organic field effect transistor (OFET) device was evaluated and proves to be film thickness dependent. For 40 nm layer thickness it displays a saturation hole mobility (μhole) of up to 0.01 cm2 V−1 s−1 and an on/off‐ratio (Ion/Ioff) of 1.5×103. When polymorphism rules: The orientation of individual molecules of a peri substituted acene with cross‐conjugated π‐systems differs significantly in its single‐crystal and thin film structure. In the latter, a most efficient face‐to‐face overlap arranges its individual arene moieties in a slipped stacking mode resulting in a close π‐π overlap. This gives rise to attractive hole carrier mobilities and decent thin film transistor properties.