We have successfully achieved a transconductance of 0.76 S/m for organic thin-film transistors with 4 V operation, which is the largest value reported for organic transistors fabricated using printing methods. Using a subfemtoliter inkjet, silver electrodes with a line width of 1 µm and a channel length of 1 µm were printed directly onto an air-stable, high-mobility organic semiconductor that was deposited on a single-molecule self-assembled monolayer-based gate dielectric. On reducing the droplet volume (0.5 fl) ejected from the inkjet nozzle, which reduces sintering temperatures down to 90 °C, the inkjet printing of silver electrodes was accomplished without damage to the organic semiconductor.

Molecules self-assembling in solution may pass through multiple phases and morphologies before reaching a thermodynamically stable state. Here we demonstrated this effect in tetracyanoquinodimethane (TCNQ), an organic molecule often used as an electron acceptor in charge transfer complex compounds. We showed that it self-assembles in a wide range of crystal habits, from nanocoils to polyhedral crystals. Scanning electron microscopy imaging on freeze-dried samples revealed the crystal growth of TCNQ starting from seed-shaped nucleation sites, progressing through flower-like structures and finally forming polyhedral micro-crystals. These results are supplemented by absorption spectroscopy as well as x-ray powder diffraction (XRPD) characterization of a powder sample.

A novel method for the in situ thermomechanical test of micro/nanoscale samples at high temperature is presented. During the in situ test, the stage is resistively heated while the temperature is measured by a cofabricated temperature sensor. For experimental demonstration of the thermomechanical testing method, we fabricate the Micro-Electro-Mechanical Systems (MEMS) stage using silicon carbide (SiC) and carry out in situ uniaxial tests for single-crystal silicon (SCS) microsamples at temperatures from room temperature to 400 °C. We recover the known elastic modulus of SCS within 1% error in this temperature range.

A method of fabricating oriented single-crystalline SrRuO3 nanowire arrays using a bottom-up approach relying on diffusion-controlled self-organization is demonstrated. DyScO3 substrates exhibiting an ordered striped phase of DyO and ScO2 chemical termination are used as a template for pulsed laser deposition growth of SrRuO3. Here SrRuO3 preferentially nucleates on one type of termination. The resulting nanowires are single crystalline, conducting and isolated from each other, typically 100 nm wide and 5–10 nm high. This preferential growth is studied using a kinetic Monte Carlo model, which provides a guide to optimize growth conditions and tune the dimensions of the nanowires.

Co3O4-based spinels are a new class of wide-band-gap p-type conductive oxides with high work functions. We examined the structures, conductivities, work functions, and optical spectra of quaternary Zn–Ni–Co–O thin films across the entire spinel region of the ZnO–NiO–Co3O4 diagram using a high-throughput combinatorial approach. We found that the conductivity of as-deposited films is maximized (100 S/cm) and optical absorption (at 1.8 eV) is minimized in different regions of the diagram, while the work function of annealed films is high and relatively constant (5.8 ± 0.1 eV). These properties made Zn–Ni–Co–O thin films applicable as p-type interlayers in solar cells. As an example, amorphous Zn–Co–O hole transport layers had good performance in bulk heterojunction organic photovoltaic devices.

We investigate the radiation response of single-walled carbon nanotube (SWCNT) thin-film transistors fabricated with 23 nm silicon oxynitride gate dielectric layers, for total ionizing doses (TIDs) of Co-60 gamma irradiation up to 2 Mrad(Si). Irradiations with ±1 MV/cm across the gate dielectric have little effect on the threshold voltage, yielding shifts of less than ±0.25 V and no detrimental effect on SWCNT mobility or maximum drain current. This illustrates the need to consider the total device material composition when investigating the radiation response of carbon nanoelectronics and substantiates the applicability of SWCNT-based nanoelectronics for use in high TID environments.

Low-voltage-driven organic thin-film transistors (organic TFTs) with spatially controlled threshold voltages (−1.2 and −0.36 V) were fabricated for the first time. Using the microcontact printing method, tetradecylphosphonic acid (HC14-PA) and pentadecylfluoro-octadecylphosphonic acid (FC18-PA) were transferred to form ultrathin layers in different regions on a substrate. Together with plasma-grown aluminum oxide (AlOx) layer, the stamped layers were shown to have equal insulating ability as the dipped method monolayer. The feasibility of the area-selective stamping method was displayed using locally controlled inverter circuits. The shift of turn-on voltage for those transistors was consistent with the threshold voltage shift of the transistors.

The extraordinary electronic, thermal, and mechanical properties of carbon nanotubes (CNTs) make them attractive materials for incorporation into polymer films. However, retaining these outstanding properties of CNTs during processing can be difficult due to the attractive forces that cause the nanotubes to bundle together. In this study, six different hydrophobically modified linear poly(ethylenimine) (LPEI) polymers are evaluated and effectively used as aqueous nanotube dispersants. This study also shows that the polymers are bifunctional in nature as aqueous polymer/nanotube mixtures can be cross-linked into CNT-impregnated hydrogels.

Highly graphitic carbons are obtained by precipitating carbon from molten steel inoculated with bismuth. Scanning electron microscopy images show that the products have a potato peel morphology. The inoculant leads to a breaking of the local symmetry of the graphitic structure as evidenced by Raman spectroscopic studies. The products exhibit flat charge–discharge profiles below about 200 mV versus Li+/Li, reversible capacities even exceeding the theoretical limit of 372 mAh/g for perfectly graphitic structures, low first-cycle irreversible capacities, and sustained hundreds of cycles.

GaN nanowires are promising building blocks for future nanoelectronics, optoelectronic devices, and nanogenerators. Here, we report on strong piezoelectricity in individual single-crystal GaN nanowires revealed by direct measurement of the piezoelectric constant using piezoresponse force microscopy. Our experimental results show that individual c-axis GaN nanowires, with a characteristic dimension as small as 65 nm, show a shear piezoelectric constant of d15 ~ 10 pm/V, which is several times that measured in bulk. The revealed strong piezoelectricity could open promising opportunities for application of GaN nanowires in nanowire-based sensors and generators for self-powered nanodevices.

This study confirms the existence of several nanometer-ordered structures in amorphous Al2O3–2SiO2–Na2O–7H2O geopolymers by high-resolution transmission electron microscopy and selected area electron diffraction. The composition ratio of the geopolymers was designed according to the NaA zeolite composition (Si/Al/Na atom ratio of 1:1:1), and the expected NaA molecular sieve was achieved by the Al2O3–2SiO2–Na2O–7H2O geopolymers through a hydrothermal reaction. This design concept was used to convert geopolymers into zeolite molecular sieves and provides a new preparation method for zeolite membranes or zeolite bulk materials.

We analyzed the contact mechanisms of bioinspired microfibrillar adhesives using in situ scanning electron microscopy. During adhesion tests we observed that (i) the superior adhesion of mushroom-shaped fibrils is assisted by the stochastic nature of detachment, (ii) the aspect ratio of microfibrils influences the bending/buckling behavior and the contact reformation, and (iii) the backing layer deformation causes the microfibrils to elastically interact with each other. These studies give new insights into the mechanisms responsible for adhesion of bioinspired fibrillar adhesives.