In this contribution, for the first time, the molecular n-doping of a donor-acceptor (D-A) copolymer achieving 200-fold enhancement of electrical conductivity by rationally tailoring the side chains without changing its D-A backbone is successfully improved. Instead of the traditional alkyl side chains for poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl](NDI)-alt-5,5'-(2,2'-bithiophene)} (N2200), polar triethylene glycol type side chains is utilized and a high electrical conductivity of 0.17 S cm after doping with (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine is achieved, which is the highest reported value for n-type D-A copolymers. Coarse-grained molecular dynamics simulations indicate that the polar side chains can significantly reduce the clustering of dopant molecules and favor the dispersion of the dopant in the host matrix as compared to the traditional alkyl side chains. Accordingly, intimate contact between the host and dopant molecules in the NDI-based copolymer with polar side chains facilitates molecular doping with increased doping efficiency and electrical conductivity. For the first time, a heterogeneous thermoelectric transport model for such a material is proposed, that is the percolation of charge carriers from conducting ordered regions through poorly conductive disordered regions, which provides pointers for further increase in the themoelectric properties of n-type D-A copolymers.

To date, there are no reports of 3D tin perovskite being used as a semiconducting channel in field‐effect transistors (FETs). This is probably due to the large amount of trap states and high p‐doping typical of this material. Here, the first top‐gate bottom‐contact FET using formamidinium tin triiodide perovskite films is reported as a semiconducting channel. These FET devices show a hole mobility of up to 0.21 cm2 V−1 s−1, an ION/OFF ratio of 104, and a relatively small threshold voltage (VTH) of 2.8 V. Besides the device geometry, the key factor explaining this performance is the reduced doping level of the active layer. In fact, by adding a small amount of the 2D material in the 3D tin perovskite, the crystallinity of FASnI3 is enhanced, and the trap density and hole carrier density are reduced by one order of magnitude. Importantly, these transistors show enhanced parameters after 20 months of storage in a N2 atmosphere.

Cell-based biosensors constitute a fundamental tool in biotechnology, and their relevance has greatly increased in recent years as a result of a surging demand for reduced animal testing and for high-throughput and cost-effective in vitro screening platforms dedicated to environmental and biomedical diagnostics, drug development and toxicology. In this context, electrochemical/electronic cell-based biosensors represent a promising class of devices that enable long-term and real-time monitoring of cell physiology in a non-invasive and label-free fashion, with a remarkable potential for process automation and parallelization. Common limitations of this class of devices at large include the need for substrate surface modification strategies to ensure cell adhesion and immobilization, limited compatibility with complementary optical cell-probing techniques, and need for frequency-dependent measurements, which rely on elaborated equivalent electrical circuit models for data analysis and interpretation. We hereby demonstrate the monitoring of cell adhesion and detachment through the time-dependent variations in the quasi-static characteristic current curves of a highly stable electrolyte-gated transistor, based on an optically transparent network of printable polymer-wrapped semiconducting carbon-nanotubes. MAIN TEXTOptical cell viability assay and immunofluorescence staining: The proliferation was evaluated after 1, 2, 3, and 4 d in vitro. For each time point the medium was removed and replaced with RPMI without phenol red containing 0.5 mg mL −1 of MTT reagent (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Sigma-Aldrich). Cells were reincubated at 37 °C for 3 h. Formazan salt produced by cells through reduction of MTT was then solubilized with 200 mL of ethanol and the absorbance was read at 560 and 690 nm (using a microplate reader TECAN Spark10M). The proliferation cell rate was calculated as the difference in absorbed intensity at 560 and 690 nm. Cells grown on glass coverslips coated with SWCNT networks were washed twice with PBS and fixed for 15 min at RT in 4 % paraformaldehyde and 4 % sucrose in 0.12 M sodium phosphate buffer, pH 7.4. Fixed cells were pre-incubated for 20 min in gelatin dilution buffer (GDB: 0.02 M sodium phosphate buffer, pH 7.4, 0.45 M NaCl, 0.2% (w/v) gelatin) containing 0.3% (v/v)

In this paper, the fabrication of carbon nanotubes field effect transistors by chemical self-assembly of semiconducting single walled carbon nanotubes (s-SWNTs) on prepatterned substrates is demonstrated. Polyfluorenes derivatives have been demonstrated to be effective in selecting s-SWNTs from raw mixtures. In this work the authors functionalized the polymer with side chains containing thiols, to obtain chemical self-assembly of the selected s-SWNTs on substrates with prepatterned gold electrodes. The authors show that the full side functionalization of the conjugated polymer with thiol groups partially disrupts the s-SWNTs selection, with the presence of metallic tubes in the dispersion. However, the authors determine that the selectivity can be recovered either by tuning the number of thiol groups in the polymer, or by modulating the polymer/SWNTs proportions. As demonstrated by optical and electrical measurements, the polymer containing 2.5% of thiol groups gives the best s-SWNT purity. Field-effect transistors with various channel lengths, using networks of SWNTs and individual tubes, are fabricated by direct chemical self-assembly of the SWNTs/thiolated-polyfluorenes on substrates with lithographically defined electrodes. The network devices show superior performance (mobility up to 24 cm V s ), while SWNTs devices based on individual tubes show an unprecedented (100%) yield for working devices. Importantly, the SWNTs assembled by mean of the thiol groups are stably anchored to the substrate and are resistant to external perturbation as sonication in organic solvents.

Platinum thin film becomes ferromagnetic when under a large electric field and in proximity to local magnetic moments.

Noncovalent functionalization of single‐walled carbon nanotubes (SWNTs) using π‐conjugated polymers has become one of the most effective techniques to select semiconducting SWNTs (s‐SWNTs). Several conjugated polymers are used, but their ability to sort metallic and semiconducting species, as well as the dispersions yields, varies as a function of their chemical structure. Here, three polymers are compared, namely, poly[2,6‐(4,4‐bis‐(2‐dodecyl)‐4H‐cyclopenta[2,1‐b;3,4b′]dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)] (P12CPDTBT), poly(9,9‐di‐n‐dodecylfluorenyl‐2,7‐diyl) (PF12), and poly(3‐dodecylthiophene‐2,5‐diyl) (P3DDT) in their ability to select two types of carbon nanotubes comprising small (≈1 nm) and large (≈1.5 nm) diameters. P12CPDTBT is a better dispersant than PF12 for small diameter nanotubes, while both polymers are good dispersants of large diameter nanotubes. However, these dispersions contain metallic species. P3DDT, instead presents the best overall performance regarding the selectivity toward semiconducting species, with a dispersion yield for s‐SWNTs of 15% for small and 21% for large diameter nanotubes. These results are rationalized in terms of electronic and chemical structure showing that: (i) the binding energy is stronger when more alkyl lateral chains adsorb on the nanotube surface; (ii) the binding energy is stronger when the polymer backbone is more flexible; (iii) the purity of the dispersions seems to depend on a strong polymer–nanotube interaction.

production of low-cost network field-effect transistors (FETs), [1] logic circuits, [2,3] and other electronic devices. [4][5][6][7][8] The polymerwrapping selection of semiconducting SWCNT was introduced by Nish et al. in 2007, [9] and improved and expanded by many authors in the last years. [10][11][12][13][14][15][16][17][18][19][20] Polyfluorene, [18,21,22] poly thiophene [23][24][25][26] derivatives, and many other polymers [27][28][29][30][31][32] are used to interact with the SWCNT walls. [33][34][35][36] However, the interaction of the polymer chains with the SWCNT is rather weak, resulting in the main advantage of this sorting method, namely the polymer wrapping does not greatly alter the electronic properties of the nanotubes. [37][38][39] In the last years, this technique has become very popular as compared with other solution-based selection processes such as density gradient ultracentrifugation and gel chromatography, in particular because of its simplicity, scalability, and high dispersion yield. [36,40,41] The mechanism of the selection process of s-SWCNT, even if still under debate, can be described as following. First, the π-π interaction is driving the polymer backbone to the SWCNT walls, and the alkyl side chains wrap around the tube limiting its interaction with the solvent. Second, the selection mechanism, as it has been speculated, arises from the screening of the s-SWCNT polarizability by wrapped poly mers. [12] The metallic-SWCNT (m-SWCNT) species have roughly three orders of magnitude larger polarizability as compared with the s-SWCNT. [42,43] It is, therefore, the large polarizability and the insufficient screening that lead to the rebundling of the m-SWCNT. [23] The significant weight difference between bundles and individualized tubes is the last ingredient, which allows for the separation of the two species by means of ultracentrifugation.Not only the polymer structure but also the chain conformation in the solvent is an important factor to obtain high selectivity and high dispersion yield. Wang et al. investigated different organic solvents for the selection process bringing forward the idea that a poor solvent for the polymer is necessary to reduce the polymer-solvent interaction and favor the interaction with the SWCNT walls. [20] Toluene has been the most used solvent as it allows to obtain a good selection yield for semiconducting tubes with many different polymers. [11,13,18,24,44,45] Unfortunately, though, the shelf lifetime of s-SWCNT inks in toluene is severely limited by nanotube aggregation and 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 perf...

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 (F4‐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 cm2 V−1 s−1 to n‐type with mobility up to 5 cm2 V−1 s−1. F4‐TCNQ transform the ambipolar transistors in p‐type with mobility up to 16 cm2 V−1 s−1.