C60 field-effect transistors:: Effects of polymerization on electronic properties and device performance

We have investigated thin-film field-effect transistors (TFT's) with C-60 as the active material, and we report the effects of photoinduced polymerization of the C-60 film. We find that the effects of a complete polymerization for a typical top-contact C-60 TFT are as follows: the electron mobility (mu(n)) at room temperature drops slightly from 0.074 to 0.068 cm(2)/(V s), the activation energy of mu(n) decreases from 0.10 meV to 0.09 meV, and the threshold voltage for TFT operation decreases markedly by similar to 15%. The latter observation suggests that the effective number of electron traps in the C-60 film decreases following polymerization. Considering that the polymerization was achieved with a low-energy HeNe laser, it is conceivable that the polymerization approach could be of interest for applications-e.g., organic bulk-heterojunction solar cells, where a stabilized C-60 morphology attained with benign means is desired.