Tunable Carbon Nanotube Mesh Fabricated Via Surfactant Assisted Direct Deposition for High Performance Transparent Electrodes

This study involved the deposition of multi-walled carbon nanotubes (MWCNTs) onto plastic, polyethylene terephalate (PET), substrates. The MWCNTs were suspended in an aqueous solution via the assistance of an ionic surfactant, sodium dodecyl sulfate (SDS). The SDS/MWCNT complexes in solution were attracted to the PET substrate because of electrostatic forces that were demonstrated by contrasting poor coverage on glass substrates.

 The solutions were deposited onto the PET films and allowed to interact for different amounts of time resulting in films that had decreasing resistivity and transparency because of increasing thicknesses.

The ratio of SDS to MWCNT to solvent, water in this case, was from an optimized MWCNT colloid study.¹ The ratio used was 10:1:1000 respectively by weight. The excess surfactant was removed at different times using the spin coating technique. Films were then rinsed in water to remove excess surfactant caught in-between the nanotubes in the mesh and then dried in an oven.

The best thin film had an average resistivity of 110 Ω/sq at 81% transmittance at 550 nm and a thickness of ± 2 um. Their performance is similar to indium tin oxide thin films as cathodes. The MWCNT and SDS composite thin films will be tested in optoelectronic applications such as solar cells and liquid crystal displays.

References

¹ Rastogi, R.; Kaushal, R.; Tripathi, S.; Sharma, A.; Kaur, I.; Bharadwaj, L. Comparative study of carbon nanotube dispersion using surfactants. 2008, J. Colloid Interface Sci. 328, 421-428.

² Jo, J.; Jung, J.; Lee, J.; Jo, W. Fabrication of Highly Conductive and Transparent Thin Films from Single Walled Carbon Nanotubes Using a New Non-ionic Surfactant via Spin. 2010, ACS Nano. 4 (9), 5382-5388.