Highly individual SWCNTs for high performance thin film electronics

Abstract

We report a continuous floating catalyst chemical vapor deposition synthesis of highly individual single-walled carbon nanotubes (SWCNT) for high performance transparent conducting films (TCF). Active feedback dilution of ferrocene-based catalyst vapor leads to an almost complete elimination of SWCNT bundling and a substantial increase in SWCNT lengths via the suppression of bundling-induced growth termination. The fabricated uniform TCFs exhibit sheet resistances of 89 Ω/sq. at 90% transmittance. This was further improved by micro-patterning, resulting in a sheet resistance of 69 Ω/sq. at 97% transmittance-the highest reported for any carbon nanotube TCFand highly competitive with commercial indium-tin-oxide-TCFs. Furthermore, we demonstrate that thin film transistors fabricated from these highly individual SWCNTs reach charge carrier mobilities up to 100 cm 2 V-1 s-1 and ON/OFF-ratios up to 10 6 .

All‐Carbon Thin‐Film Transistors as a Step Towards Flexible and Transparent Electronics

“…[90] When individual CNTs were used to assembly the TCFs with microgrid structure, the optoelectrical performance of flexible CNT TCFs was greatly improved with a sheet resistance up to 69 Ω sq -1 at 97% transmittance. [91,92] These results further demonstrate that the control and elimination of bundling are essential for optimizing the performance of CNT TCFs. Note that patterning of TCFs is one of the key processes for fabricating transparent electrodes, so the traditional lithography technique inevitably leads to a decrease of the conductivity of electrodes due to the contamination of CNTs by the photoresist.…”

“…[91] Copyright 2016, Elsevier. d) Approximate distribution of the optoelectrical performance of CNT TCFs prepared by dry-drawing, [57] solution processing, [63,77] gas filtration, [82][83][84] and gas filtration with grids, [90,91] in comparison with that of ITO, [93,94] Ag nanowire [93,94] and PEDOT:PSS TCFs. [94] The transmittance data is given for a wavelength of 550 nm.…”

“…[27] A CNT thin film with a micro-grid pattern further improved the TCF performance to 69 Ω sq -1 at 97% transmittance. [28] Such carbon-based TCFs are superior or comparable in optoelectrical performance to ITO and metal nanowire TCFs. Moreover, they can be formed on various flexible substrates by a transfer process under non-vacuum and low temperature conditions.…”

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

“…For practical application, industry specification for transparent conducting films requires transparencies higher than 90% and sheet resistance R sq lower than 90 ohm/sq (see, e.g., [13]). The highly transparent (80-90%) SWCNT films formed from pristine nanotubes with noticed M/S ratio have the values of R sq ranging from unacceptable values (10 3 -10 4 ohm/sq) [2,8] to those (89-310 ohm/sq) [4,[14][15][16] which are in close proximity to required ones. 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 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].…”