Stable Charge-Transfer Doping of Transparent Single-Walled Carbon Nanotube Films

Abstract

Single walled carbon nanotube (SWCNT) films are candidates for use as transparent electrodes, especially where low-cost, flexible materials are desired. Chemical doping is a critical step in fabricating conductive films as doping substantially decreases the sheet resistance within SWCNTs and at tube−tube junctions. Despite the importance of chemical doping, surprisingly little effort is devoted to developing doping chemistry. Concentrated acid solutions are typically used to dope SWCNT films. Although they are effective at reducing the sheet resistance of SWCNT films, this method is plagued by two critical drawbacks. The first is that concentrated acid baths, such as HNO3, are extremely harsh and will damage virtually any device technology. Second, the film resistance is unstable and rises dramatically over time. These drawbacks make implementation of SWCNT transparent, conducting films in technological applications extremely difficult. Here, we report an alternative doping scheme that utilizes a single-electron oxidant (triethyloxonium hexachloroantimonate) to effectively dope the SWCNT films. As evidenced by optical and electrical measurements, the compound effectively p-dopes SWCNT films. In addition to the effective doping, the resultant film resistance is stable over time. The films doped with triethyloxonium hexachloroantimonate outperform nitric acid doped films by a factor of 2.5 over time. This study introduces a new category of chemical dopants that yield stable, transparent, and conductive SWCNT films suitable for technological applications.

Efficient and bright organic light-emitting diodes on single-layer graphene electrodes

“…1a. A similar doping process has been studied for carbon nanotubes 32 and found to be stable over time, in contrast with the commonly used nitric acid doping. The work functions of graphene samples before and after chemical doping were measured by Raman spectroscopy (Fig.…”

Resist-free fabricated carbon nanotube field-effect transistors with high-quality atomic-layer-deposited platinum contacts

“…CNTFETs were fabricated in back-gate geometry using p-doped Si substrates covered with a 10 nm thermal SiO 2 dielectric. Carbon nanotubes synthesized by laser ablation (1-3 lm long, 0.5-1.5 nm diameter) were purified 35 and dispersed on these substrates. The source and drain contacts were patterned by Pt EBID using an electron dose of 15 pC/lm 2 , and thickened by 1000 cycles of Pt thermal ALD.…”

Fully Solution-Processed Semitransparent Organic Solar Cells with a Silver Nanowire Cathode and a Conducting Polymer Anode

“…1 ITO, however, suffers from several drawbacks that limit its viability as a TCE for next-generation optoelectronics, including high cost, poor performance on plastic substrates, and a tendency to crack when flexed. 2,3 Potential solution-processable alternatives to ITO include carbon nanotubes, 4,5 graphene, [6][7][8][9] conducting polymers, 10,11 and metal nanowires [12][13][14][15] Single-Walled Carbon Nanotubes (SWCNTs) are attractive TCE materials due to their high intrinsic conductivity and mechanical durability but, owing to large inter-tube resistances, their reported performance characteristics are significantly worse than ITO. The need for aggressive acid treatments to induce p-type doping of semiconducting tubes and the non-permanent nature of the doped state are also problematic.…”