We describe the modular synthesis of three novel large N-heteroarenes, containing 9, 11, and 13 annulated rings. This modular system features fused azaacene units to a coronene nucleus. We evaluate the optical and electronic properties and the solid-state packing of the targets. The electronic properties of the 13-ring N-heteroarene allow the fabrication of a proof-of-concept thin-film transistor. Electron mobilities up to 8 × 10(-4) cm/(V s) were obtained for polycrystalline films.

A cyclocondensation of TIPS-ethynyl-substituted diaminoarenes with in situ obtained 4,5-dibromocyclohexa-3,5-diene-1,2-dione has led to the synthesis of tetrabromotetraazapentacene (BrTAP). BrTAP is easily reduced to its air-stable radical anion and electron mobilities >0.56 cm V s can be achieved in thin-film transistors.

The electronic structure of organic/metal interfaces and thin films is essential for the performance of organic-molecule-based field effect transistors and solar cells. Here, we investigated the adsorption and electronic properties of the N-heteropolycyclic aromatic compound 6,13-diazapentacene (DAP), a potential electron-transporting semiconductor on Au(111), using temperature-programmed desorption, vibrational and electronic high-resolution electron energy loss spectroscopy, two-photon photoemission spectroscopy, and state-of-the-art quantum chemical methods. In the mono- and multilayer regime DAP adsorbs in a planar fashion with the molecular backbone oriented parallel to the gold substrate. The energetic position of transport levels (electron affinities and ionization potentials) and singlet (S) as well as triplet (T) transition energies are quantitatively determined. The lowest affinity level is located at 3.48 eV, whereas the energetic position of the first excitonic state is at 4.00 eV, resulting in an exciton binding energy of 0.52 eV. Compared to pentacene, the optical gap is reduced by 0.1 eV and the α-band gains substantially in intensity, which is explained by a detailed analysis of the electronic structure. The optical gap, i.e., the S1 excitation energy, is determined to be 2.0 eV, and the T1 transition energy is 0.9 eV, making an exothermic singlet fission process relevant in organic photovoltaics feasible.

The synthesis and structural properties of three N,N 0 -dihydrotetraazapentacenes (DHTA) are described. The different substitution pattern (H, F, Cl) of the dihydrotetraazapentacene body exhibited a significant effect on the optical, electronic and morphological properties of the derivatives in thin films. The synthesised materials were investigated as active layers in top gate/bottom contact (BC/TG) transistors. The transistor performance of the dichlorinated derivative was almost independent on the processing conditions with an average hole mobility of $0.04 cm 2 V À1 s À1 and best mobility values ranging from 0.07 to 0.11 cm 2 V À1 s À1 . Each of the three derivatives was found to exhibit an individual packing motif in solution grown crystals, determined by single crystal X-ray analysis. Surprisingly, for all three materials a different polymorph formed in spin cast films explaining the observed morphology and FET performance. Fig. 2 AFM height images (30 Â 30 mm 2 ) of the polycrystalline films of DHTA-H 2 , DHTA-Cl 2 , and DHTA-F 2 . Spin-coated films on polyimide from tetralin, mesitylene and xylene.This journal is