Trialkylsilylethynyl-Functionalized Tetraceno[2,3-b]thiophene and Anthra[2,3-b]thiophene Organic Transistors

A series of ethynyl-substituted molecules with the tetraceno[2,3- b ]thiophene and anthra[2,3- b ]thiophene core have been synthesized. The aim was to investigate the impact of differently bulky side-chain substituents on the packing of the molecule in thin film and hence its thin-film transistor (TFT) mobility. Three R groups were used, namely, the tri-isopropyl-, triethyl-, and trimethylsilylethynyl groups. We did not observe a direct correlation between substituent size and TFT mobility. However, the 5,12-bis(tri-isopropylsilylethynyl)tetraceno[2,3- b ]thiophene has a mobility as high as 1.25 cm 2 /V·s, the 5,12-bis(trimethylsilylethynyl)tetraceno[2,3- b ]thiophene has a mobility of about 0.00616 cm 2 /V·s, while 5,10-bis(triethylsilylethynyl)anthra[2,3- b ]thiophene and 5,10-bis(trimethylsilylethynyl)anthra[2,3- b ]thiophene have a mobility of 10 −4 cm 2 /V·s on phenylsilane- and octadecyltrichlorosilane-treated surfaces respectively.