High conductivity transparent carbon nanotube films deposited from superacid

Abstract

Carbon nanotubes (CNTs) were deposited from a chlorosulfonic superacid solution onto PET substrates by a filtration/transfer method. The sheet resistance and transmission (at 550 nm) of the films were 60 Ω/sq and 90.9% respectively, which corresponds to a DC conductivity of 12,825 S cm(-1) and a DC/optical conductivity ratio of 64.1. This is the highest DC conductivity reported for CNT thin films to date, and attributed to both the high quality of the CNT material and the exfoliation/doping by the superacid. This work demonstrates that CNT transparent films have not reached the conductivity limit; continued improvements will enable these films to be used as the transparent electrode for applications in solid state lighting, LCD displays, touch panels, and photovoltaics.

The effects of percolation in nanostructured transparent conductors

“…The best sample was for nanotubes deposited from superacids whose most promising fi lm displayed T ≈ 91% and R s ≈ 60 Ω /sq. 72 Looking at the 10 best values ( Figure 2 inset), it is clear that the spread is very tight, with the top 10 varying in σ dc,B / σ op from 12 to 60. This refl ects the relative maturity of nanotube-based transparent conductor research and may suggest that this technology is approaching physical limits, possibly set by the high inter-nanotube junction resistance.…”

Flexible transparent conductive materials based on silver nanowire networks: a review

“…Another dependency should be considered for the high-transparency regime where deviation from bulk-like behaviour is observed and can be explained by percolation effects as revealed by the good fit between the dashed lines Reprinted with permission from [118]. (b) Optical transmittance (at 550 nm) versus sheet resistance for graphene [14][15][16][17][18][19], carbon nanotubes [11,[20][21][22][23][24][25][26], AgNWs [27][28][29][30][31][32][33] and ITO [9,11,13]. Solid lines exhibit iso-values of the figure of merit (see text for explanations).…”

Phonon contribution to electrical resistance of acceptor-doped single-wall carbon nanotubes assembled into transparent films

“…The sheet resistance of pristine SWCNT films depends on the purity of the samples, the length and diameter of the nanotubes, and the size of the SWCNT bundles [13,15]. The best value of R sq = 89 ohm/sq has been obtained for 90%-transparent SWCNT films fabricated using aerosol technology, which leads to an almost complete elimination of SWCNT bundling (known for such technique as arc discharge [17]) and a substantial increase in SWCNT lengths via the suppression of bundling-induced growth termination [16] The sheet resistance of SWCNT films can be significantly decreased by acid(HNO 3 ) treatment that results in a high level of p-type doping [9,14,18,19]. The other examples of strong acceptors for p-type doping are iodine and cuprous chloride (CuCl) [20][21][22][23][24].…”