Rodlike Tetracene Derivatives

5 years ago

Rodlike Tetracene Derivatives

Michael Roth, Marcus Ahles, Roland Schmechel, Christian Gawrisch, Christian Melzer, Matthias Rehahn, Heinz von Seggern, Thorsten Schwalm

Efficient and versatile synthetic access to rodlike tetracene derivatives was developed by means of Diels–Alder cycloaddition, halogenation, halogen–metal exchange, and transition metal mediated coupling reactions. Herein, the synthesis and structural, electrical, and charge-transport properties of three of the resulting materials, namely, 2-(tetracen-2-yl)tetracene, 1,4-bis(2-tetracenyl)benzene, and 2,5-bis(2-tetracenyl)thiophene, are presented. Good crystallization behavior on SiO2 substrates, narrowing of the bandgap by 0.2 eV, and a decrease of the ionization potential of more than 0.5 eV compared to tetracene were observed. Charge-carrier field-effect mobilities on the order of 10−1 cm2 V−1 s−1, on/off ratios of 105, and threshold voltages Vth<15 V were found in thin-film organic field-effect transistors prepared by standard high-vacuum deposition techniques. Different aspects: By merging two tetracenes, new ridged-rod tetracene derivatives with different aspect ratios were realized. Coupling of the two tetracenes reduces the bandgap and ionization potential. Good crystallinity on SiO2 substrates was observed. Thus, decent performance in organic field-effect transistors was found (see figure), but increasing the aspect ratio beyond that of directly linked tetracenes did not result in improved crystallinity or transport properties. DDQ: 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, DT: ditetracene, SYC: Semmelhack–Yamamoto coupling.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201702382