Conjugated polymer-controlled selective dispersion of single-walled carbon nanotubes and fabrication of network transistors

A family of polymers based on fluorene including homopolymers, alternating copolymers and two fourarmed polymers are synthesized by polycondensation. Their ability to selectively wrap specific (n, m) species using HiPco single-walled carbon nanotubes (SWNTs) as a raw material is investigated. Fluorescence, absorption and Raman spectroscopies are used to analyze SWNT species after addition to polymer suspensions. The results show separation of (n, m) SWNTs can be realized using an optimized polymer structure. The optimized polymer contains fluorene in the main chain to preferentially separate semiconducting nanotube species and hydrofluoric acid (HF)-degradable disilane groups so that it can be removed from the SWNTs after separation. We used the enriched SWNTs to prepare a solution-processed field-effect transistor with a random nanotube network in the active channel to demonstrate the selectivity of the polymer for (n, m) SWNTs. The device exhibits stable p-type semiconductor behavior in air with an on/off current ratio of 121 and hole mobility of 3.2 cm(2)V(-1)s(-1).