Rodlike Tetracene Derivatives

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.