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Polarity control in semiconducting single-walled carbon-nanotube field-effect transistors (s-SWNT FETs) is important to promote their application in logic devices. The methods to turn the intrinsically ambipolar s-SWNT FETs into unipolar devices that have been proposed until now require extra fabrication steps that make preparation longer and more complex. It is demonstrated that by starting from a highly purified ink of semiconducting single-walled carbon nanotubes sorted by a conjugated polymer, and mixing them with additives, it is possible to achieve unipolar charge transport. The three additives used are benzyl viologen (BV), 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI), which give rise to n-type field-effect transistors, and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F-4-TCNQ) which gives rise to p-type transistors. BV and N-DMBI transform the s-SWNTs transistors from ambipolar with mobility of the order of 0.7 cm(2) V-1 s(-1) to n-type with mobility up to 5 cm(2) V-1 s(-1). F-4-TCNQ transform the ambipolar transistors in p-type with mobility up to 16 cm(2) V-1 s(-1).

Printed random networks of polymer-wrapped multi-chiral semiconducting carbon nanotubes (s-SWCNTs) are an opportunity for mass-manufacturable, high-performance large-area electronics. To meet this goal, a deeper understanding of charge-transport mechanisms in such mixed networks is crucial. Here, charge transport in field-effect transistors based on inkjet-printed s-SWCNTs networks is investigated, obtaining direct evidence for the phases probed by charge in the accumulated channel, which is critical information to rationalize the different transport properties obtained for different printing conditions. In particular, when the fraction of nanotubes with smaller bandgaps is efficiently interconnected, the sparse network provides efficient charge percolation for band-like transport, with a charge mobility as high as 20.2 cm(2) V-1 s(-1). However, when the charges are forced by a less efficient morphology, to populate also higher bandgap nanotubes and and/or the wrapping polymer, thermally activated transport takes place and mobility drops. As a result, a trade-off between network density and charge transport properties is identified for device current optimization, in both p- and n-type regimes. These findings shed light on the fundamental aspects related to charge transport in printed s-SWCNT mixed networks and contribute to devise appropriate strategies for the formulation of inks and processes towards cost-effective mass production schemes of high-performance large-area electronics.

Semiconducting single‐walled carbon nanotubes (s‐SWNTs) are used as a protective interlayer between the lead sulfide colloidal quantum dot (PbS CQD) active layer and the anode of the solar cells (SCs). The introduction of the carbon nanotubes leads to increased device stability, with 85% of the initial performance retained after 100 h exposure to simulated solar light in ambient condition. This is in sharp contrast with the behavior of the device without s‐SWNTs, for which the photoconversion efficiency, the open circuit voltage, the short‐circuit current, and the fill factor all experiencing a sharp decrease. Therefore, the inclusion of s‐SWNT as interlayer in CQD SCs, give rise to SCs of identical efficiency (above 8.5%) and prevents their performance degradation. ISSN:2196-7350

In the past years, high-quality semiconducting single-walled carbon nanotube (s-SWCNT) inks obtained by conjugated polymer wrapping using toluene as solvent have been used for the fabrication of high-performance field-effect transistors. Charge-carrier mobilities up to 50 cm(2) V-1 s(-1) and on/off ratios above 10(8) have been reported for devices based on networks of s-SWCNT. However, devices fabricated from inks that are only a few weeks old generally show a marked decrease in performance, indicating the limited shelf life of toluene-based inks. The use of o-xylene as applicator solvent to obtain high quality and very stable s-SWCNT inks is reported. The charge carrier mobility of field-effect transistors fabricated with this new ink show a twofold increase in magnitude compared to devices prepared from a toluene solution. More importantly, the device-to-device performance shows improved reproducibility, which is ascribed to the higher degree of homogeneity of the s-SWCNT network deposited from o-xylene with respect to the one from toluene. Finally, the o-xylene inks maintain their initial properties for longer than one year. This very long shelf life is an important pre-condition for the industrial use of s-SWCNT inks.

A demonstration of ambipolar transistors of polymer-wrapped single-walled carbon nanotubes (SWNTs) provides an opportunity to scrutinize transport mechanism of electrons and holes in this system. Anomalous temperature-dependent nonlinear transport behavior is observed in large diameter SWNTs. This suggests an interplay between the intrinsic transport of individual tubes and the percolative network properties, highlighting the nature of polymer-wrapped SWNTs as a complex hybrid material.

Noncovalent functionalization of carbon nanotubes by wrapping them using pi-conjugated polymers is one of the most promising techniques to sort, separate, and purify semiconducting nanotube species for applications in optoelectronic devices. However, wide energy bandgap polymers commonly used in this technique reduce charge transport through the nanotube network. To avoid the formation of insulating barriers between the tubes, challenging procedures for the removal of the polymer from the nanotube walls are necessary. Here, the use of two narrow bandgap polymers based on naphthalene-bis(dicarboximide) (NDI), namely, poly{[N, N'-bis(2-octyldodecyl)- naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)}, (P(NDI2OD-T-2 or ActivInk N2200) and its molecular cousin, poly{[(N, N'-bis(2-octyldodecyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl)alt -5,5'-(2,2'-bithiophene)]-co -[(N, N'-bis(2-octyldodecyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl)-alt -5,5'-(2,2'-(4,4'-dimethoxybithiophene))]}(ActivInk PE-N-73), for selecting semiconducting single-walled carbon nanotubes (s-SWNTs) is demonstrated. The influence of the chemical structure of these polymers on the nanotube selectivity, as well as the effect of residual excess polymer and their band-gaps, are investigated through optical spectroscopy and charge transport measurements. While the electron transport of the devices fabricated with PE-N-73 and N2200 wrapped SWNTs is comparable, a substantial difference is observed in the hole transport. The better alignment of the HOMO level of PE-N-73 with that of the nanotubes allows achieving improved p-type characteristics even with a large amount of residual polymer in the network.