Controlled enhancement of the electron field-effect mobility of F16CuPc thin-film transistors by use of functionalized SiO2 substrates

We present a comparative study of copper-hexadecafluorophthalocyanine (F16CuPc) films grown on bare SiO2 and on SiO2 functionalized by octadecyltrimethoxisilane (OTMS), a methyl terminated molecular layer with a lower surface energy than SiO2. We show that the functionalization of SiO2 by OTMS leads to the formation of highly structurally ordered F16CuPc crystallites. The extended lateral order and subsequent reduction of grain boundaries result in an improved field-effect mobility for electrons by almost an order of magnitude in thin-film transistors made of these films.