SORTING SEMICONDUCTING SINGLE-WALLED CARBON NANOTUBES AND USING THEM AS RANDOM NETWORK OF FIELD-EFFECT TRANSISTORS

Single-walled carbon nanotubes (SWCNTs) with incovalently attached iodine, were obtained by physical absorption. The different diameter sizes of SWCNTs, with different numbers of iodine molecule, enhance the density contrast between them which becomes evident in density gradient ultracentrifugation (DGU) targeted to sort certain species of SWCNTs. The results of optical absorbance and photoluminescence emission showed that iodine-assisted DGU preferentially separates semiconducting nanotubes with certain diameters [(6, 5), (7, 5), (8, 4), and (7, 6)]. We have applied these semiconducting, species enriched SWCNTs to prepare solution-processed field effect transistor (FET) devices with random nanotube network active channels. The devices exhibit stable p-type semiconductor behavior in air with very promising characteristics. The on-off current ratio reaches up to 2 x 10(4) within a narrow window of voltage (-10V to 10 V), and estimated hole mobility of 21.7 cm(2) V-1 s(-1).