Charge Transport Capabilities of Dibenzo[n]phenacenes (n = 5–7): Influence of Trap States and Molecular Packing

Abstract

A high carrier transport capability with strong π–π interactions is expected to result from the extension of π conjugation in small molecules. This is an important factor to create promising molecules, leading to the development of high-performance and new applications in organic electronic devices. We systematically demonstrate the charge transport capability and trap density of states in dibenzo[n]phenacenes (DBnPs) (n = 5–7) with a hybrid π structure between the phenacene and acene cores. A DB6P field-effect transistor (FET) achieves a relatively high-field-effect mobility beyond 2 cm2 V–1 s–1, which indicates excellent FET performance in comparison with DB5P and DB7P. The calculated charge-transfer integrals based on the crystal structure and the distribution of the trap density of states confirm the superior transport capability and FET properties in DB6P. We demonstrate that molecules with C2h symmetry result in high crystallinity and close packing in crystals, leading to high-performance FETs.