RESUMEN
We investigated the wrinkle formation on ion-beam (IB)-irradiated substrates coated with the thermoplastic elastomer styrene-b-isoprene-b-styrene (SIS) and demonstrate a relation of the wrinkle structure and the newly formed top layer induced by IB. IB irradiation led to polymer cross-linking on the surface, thereby forming a new skin layer, a finding which was supported by an X-ray photoelectron spectroscopy analysis, Young moduli calculated using force-distance curves, and time-of-flight secondary ion mass spectrometry depth profiling. The wrinkle wavelength increased according to the irradiation time, which indicates that the latter mainly increased the thickness of the cross-linking layer. The increase in the wrinkle wavelength varied from 420 to 670 nm by changing the IB irradiation time. In this paper, we present not only the expectation of wrinkle fabrication using our method but also the possibility of choosing diverse materials such as the thermoplastic elastomer SIS for fabrication of wrinkle structures.
RESUMEN
Surface wrinkling method is used to fabricate a 1-dimensional nanostructure. The structure is transferred to an ultraviolet cured polymer which is used as an alignment layer. The anisotropic geometry serves as a guide for aligning liquid crystal molecules uniformly without defects. The TN-LC cell showed a successful LC switching, with a response time of 20.5 ms, and a threshold voltage of 2.00 V. It also exhibited high thermal stability above 180°C. The proposed UV-cured polymers with 1-D nano wrinkle geometry can be a candidate for alternative alignment techniques, for advanced liquid crystal devices with high thermal budgets.
RESUMEN
The present study demonstrates that surface reformation in polydimethylsiloxane can be controlled using ion-beam (IB) irradiation. This can be done by simply varying the IB incidence angle and requires no change in the energy source. By controlling the incidence angle of IB irradiation, we were able to continuously control the pattern of the wrinkle structure, that is, a randomly formed pattern or an anisotropic one. Moreover, the directional characteristics of the wrinkle pattern control the alignment of liquid crystal molecules. This control is a function of the incidence angle of the IB. These simple methods can provide considerable flexibility in the fabrication of wrinkle structures.
RESUMEN
In the past decade, hybrid materials for highly stretchable, conductive electrodes have received tremendous attention in the fields of emerging wearable electronic, optoelectronic, and sensing devices. Here, we present a previously unrecognized aqueous route to producing stretchable conductors composed of silver nanoparticles (AgNPs) and single-walled carbon nanotubes (SWNTs) embedded in a polyurethane (PU) matrix, in contrast to ones dispersed in toxic organic solvents reported to date. The intact chemical interaction between one-dimensional SWNTs, for endowing the capability of establishing conductive pathways even in stretching conditions, and AgNPs, for enabling high conductivity of the composites, is achieved in an aqueous medium with an anionic polyelectrolyte, poly(acrylic acid), that undergoes pH-dependent conformational evolution. With this aqueous approach, we demonstrate that AgNP-SWNT-PU composites supported on PDMS substrates have the conductivities of 620 and 120 S cm-1 in unstrained and 90% elongated conditions, respectively, and display repeatable reversibility at a strain of 60%.
RESUMEN
Y2O3-doped IZO (YIZO) films was investigated in order to control the carrier concentration of semiconducting IZO layer. Stoichiometric thin YIZO films were deposited on glass substrates by RF magnetron sputtering method using indium zinc oxide (IZO) including 50 wt.% ZnO and Y2O3 targets. During the deposition of YIZO films, the working pressure was fixed at 0.17 Pa and the deposition temperature was kept at room temperature while the oxygen partial pressure (P(O2)) was changed to find the optimal film condition. In order to check the PO2 effect on structural, electrical and optical properties of the grown YIZO layer on glass, X-ray diffraction (XRD) was employed to analyze the structure of YIZO films and the electrical properties were characterized by Hall measurements using the Van der Pauw geometry at room temperature. From the measured XRD patterns, exhibiting crystalline peak of the YIZO film deposited under PO2 condition is revealed while amorphous phase structure is only observed from the YIZO film deposited under pure Ar gas condition. As the O2 contents in gas increase, the resistivity of YIZO film also drastically increases, whereas the carrier concentration of the YIZO films sharply decreases with mobility.
RESUMEN
We report the structural, electrical, and optical characteristics of Al-doped ZnO (ZnO:Al) films deposited on glass by atomic layer deposition (ALD) with various Al2O3 film contents for use as transparent electrodes. Unlike films fabricated by a sputtering method, the diffraction peak position of the films deposited by ALD progressively moved to a higher angle with increasing Al2O3 film content. This indicates that Zn sites were effectively replaced by Al, due to layer-by-layer growth mechanism of ALD process which is based on alternate self-limiting surface chemical reactions. By adjusting the Al2O3 film content, a ZnO:Al film with low electrical resistivity (9.84 x 10(-4) Omega cm) was obtained at an Al2O3 film content of 3.17%, where the Al concentration, carrier mobility, optical transmittance, and bandgap energy were 2.8 wt%, 11.20 cm2 V(-1) s(-1), 94.23%, and 3.6 eV, respectively. Moreover, the estimated figure of merit value of our best sample was 8.2 m7Omega(-1). These results suggest that ZnO:Al films deposited by ALD could be useful for electronic devices in which especially require 3-dimensional conformal deposition of the transparent electrode and surface passivation.
RESUMEN
Annealing effect on structural and electrical properties of W-doped IZO (WIZO) films for thin film transistors (TFT) was studied under different process conditions. Thin WIZO films were deposited on glass substrates by RF magnetron co-sputtering technique using indium zinc oxide (10 wt.% ZnO-doped In2O3) and WO3 targets in room temperature. The post annealing temperature was executed from 200 degrees C to 500 degrees C under various O2/Ar ratios. We could not find any big difference from the surface observation of as grown films while it was found that the carrier density and sheet resistance of WIZO films were controlled by O2/Ar ratio and post annealing temperature. Furthermore, the crystallinity of WIZO film was changed as annealing temperature increased, resulting in amorphous structure at the annealing temperature of 200 degrees C, while clear In2O3 peak was observed for the annealed over 300 degrees C. The transmittance of as-grown films over 89% in visible range was obtained. As an active channel layer for TFT, it was found that the variation of resistivity, carrier density and mobility concentration of WIZO film decreased by annealing process.
RESUMEN
We first investigated the alignment characteristics of tin (IV) oxide (SnO(2)) thin films deposited by radio-frequency (RF) magnetron sputtering. This study demonstrates that liquid crystal (LC) molecules could be aligned homogeneously by controlling the Ion Beam (IB) irradiation energy densities. We also show that the pretilt angle of the LC molecules has a close relation with the surface energy. X-ray photoelectron spectroscopy (XPS) indicates that a non-stoichiometric SnO(2-x) surface converted by ion beam irradiation can horizontally align the LC molecules. The measured electro-optical (EO) characteristics showed high performance, comparable with those of rubbed and ion-beam irradiated polyimide (PI) layers.
