Conjugated Polymers with Immolative Side Chains Enable Conductive, Flexible, Transparent Carbon Nanotube Films

Single-walled carbon nanotubes (SWNTs) are promising materials for building transparent conducting films (TCFs). Nevertheless, commercially available SWNTs exhibit low purity and poor solubility. Conjugated polymers (CPs) have been widely reported to disperse SWNTs in organic solvents; however, converting CP-SWNT dispersions into TCFs has never been investigated. In this study, we used the poly(fluorene-co-phenylene) CP with self-immolative linkers (SILs) within its side chains to disperse SWNTs. The SIL enables clean and fast side chain removal from the CP-SWNT complex upon simple treatment with tetra-n-butylammonium fluoride (TBAF) and subsequently decreases the sheet resistance (Rs) of the CP-SWNT thin films. We explored a highly reproducible method to manufacture CP-SWNT-TCFs on a Mylar substrate. All CP-SWNT-TCFs showed a significant decrease in Rs post TBAF treatment, suggesting that eliminating the side chain can decrease Rs while preserving %transmittance. Notably, these CP-SWNT-TCF films exhibited consistent Rs across various bending radii and after 200 bending cycles, highlighting their applicability in flexible electronics. This proof-of-concept study opens up avenues to produce CP-SWNT-TCF and further enhance their electrical conductivity by removing CP side chains.