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Zn-doped SnOx/Ag/Zn-doped SnOx(ZTO/Ag/ZTO) multilayer thin films fabricated on a polyethylene terephthalate (PET) substrate using an optimized N2-to-(Ar + O2) gas ratio are used for transparent thin-film heaters with high performance and chemical stability. The ZTO/Ag/ZTO-based multilayer thin film exhibits enhanced durability at high temperatures and humid environments by incorporating nitrogen. The bending test results—there was no significant change in the sheet resistance even after 10,000 bending cycles—highlight the mechanical flexibility of the ZTO/Ag/ZTO multilayer thin film. The ZTO/Ag/ZTO-based thin-film heater on PET, fabricated under optimized deposition gas conditions, exhibits a fast thermal response time of 30 s and a low driving voltage of 6 V to attain 100 °C. It also exhibits uniform heat distribution at saturated temperature and chemical stability after 100 heating–cooling cycles. Hence, the proposed ZTO/Ag/ZTO-based thin-film heater is applicable for use in front and rear window automobile and building applications.

Organic electronic devices such as organic light-emitting diodes (OLEDs), quantum dot LEDs, and organic photovoltaics are promising technologies for future electronics. However, achieving long-term stability of organic-based optoelectronic devices has been regarded as a crucial problem to be solved. In this work, a simple and reproducible fabrication method for ultralow water permeation barrier films having a triple-layered (triad) hydrogenated silicon nitride (a-SiNx:H)/nanosilicon oxynitride (n-SiOxNy)/hybrid silicon oxide (h-SiOx) multistructure is presented. Two triad (a-SiNx:H/n-SiOxNy/h-SiOx)n=2multistructure barrier films are deposited on both sides of a poly(ethylene terephthalate) substrate using a combination of low-pressure plasma-enhanced chemical vapor deposition and dip coating. The deposited films show a high average transmittance (400–700 nm) of 84% and an ultralow water vapor transmission rate of 2 × 10–6g/m2/day. In the electroluminescence characteristics of OLEDs encapsulated with two triad barrier films, the operational lifetime (T50) of OLEDs is 1584 h, which is almost similar to that (1416 h) of OLEDs encapsulated with a glass lid.

In modern society, advanced technology has facilitated the emergence of multifunctional appliances, particularly, portable electronic devices, which have been growing rapidly. Therefore, flexible thermally conductive materials with the combination of properties like outstanding thermal conductivity, excellent electrical insulation, mechanical flexibility, and strong flame retardancy, which could be used to efficiently dissipate heat generated from electronic components, are the demand of the day. In this study, graphite fluoride, a derivative of graphene, was exfoliated into graphene fluoride sheets (GFS) via the ball-milling process. Then, a suspension of graphene oxide (GO) and GFSs was vacuum-filtrated to obtain a mixed mass, and subsequently, the mixed mass was subjected to reduction under the action hydrogen iodide at low temperature to transform the GO to reduced graphene oxide (rGO). Finally, a highly flexible and thermally conductive 30-μm thick GFS@rGO hybrid film was prepared, which showed an exceptional in-plane thermal conductivity (212 W·m–1·K–1) and an excellent electrical insulating property (a volume resistivity of 1.1 × 1011Ω·cm). The extraordinary in-plane thermal conductivity of the GFS@rGO hybrid films was attributed to the high intrinsic thermal conductivity of the filler components and the highly ordered filler alignment. Additionally, the GFS@rGO films showed a tolerance to bending cycles and high-temperature flame. The tensile strength and Young’s modulus of the GFS@rGO films increased with increasing the rGO content and reached a tensile strength of 69.3 MPa and a Young’s modulus of 10.2 GPa at 20 wt % rGO. An experiment of exposing the films to high-temperature flame demonstrated that the GFS@rGO films could efficiently prevent fire spreading. The microcombustion calorimetry results indicated that the GFS@rGO had significantly lower heat release rate (HRR) compared to the GO film. The peak HRR of GFS@rGO10 was only 21 W·g–1at 323 °C, while that of GO was 198 W·g–1at 159 °C.

Owing to the growth of demand for highly integrated electronic devices, high heat dissipation of thermal management materials is essential. Epoxy composites have been prepared with vertically aligned (VA) three-dimensional (3D)-structured SiC sheet scaffolds. The required VA-SiC sheet scaffolds were prepared by a novel approach starting with a graphene oxide (GO) scaffold. The VA-GO scaffolds were reduced to VA-graphene scaffolds in an argon environment, and the latter were subsequently transformed into VA-SiC sheet scaffolds by a template-assisted chemical vapor deposition method. Epoxy resin was filled in the empty spaces of the 3D scaffold of SiC sheets to prepare the composite mass. The material so prepared shows anisotropic thermal property with ultrahigh through-plane conductivity of 14.32 W·m–1·K–1at a SiC sheet content of 3.71 vol %. A thermal percolation is observed at 1.78 vol % SiC filler. The SiC sheet scaffold of covalently interconnected SiC nanoparticles plays a vital role in the formation of the thermal conductive network to significantly enhance the thermal conductivity of epoxy composites. The application of the VA-SiC/epoxy composite as an efficient thermal dissipating material has also been presented. The VA-SiC/epoxy composites have a strong potential for preparing heat-dissipating components in integrated microelectronics.

All-solid-state thin-film batteries have been actively investigated as a power source for various microdevices. However, insufficient research has been conducted on thin-film encapsulation, which is an essential element of these batteries as solid electrolytes and Li anodes are vulnerable to moisture in the atmosphere. In this study, a hybrid thin-film encapsulation structure of hybrid SiOy/SiNxOy/a-SiNx:H/Parylene is suggested and investigated. The water-vapor transmission rate of hybrid thin-film encapsulation is estimated to be 4.9 × 10–3g m–2·day–1, a value that is applicable to batteries as well as flexible solar cells, thin-film transistor liquid-crystal display, and E-papers. As a result of hybrid thin-film encapsulation, it is confirmed that the all-solid-state thin-film batteries are stable even after 100 charge/discharge cycles in the air atmosphere for 30 days and present a Coulombic efficiency of 99.8% even after 100 cycles in the air atmosphere. These results demonstrate that the thin-film encapsulation structure of hybrid SiOy/SiNxOy/a-SiNx:H/Parylene can be employed in thin-film batteries while retaining long-term stability.

A solar-driven photoelectrochemical (PEC) cell is emerging as one of the promising clean hydrogen generation systems. Engineering of semiconductor heterojunctions and surface morphologies of photoelectrodes in a PEC cell has been a primitive approach to boost its performance. This study presents that a molybdenum disulfide (MoS2) nanoflakes photoanode on 3-dimensional (3D) porous carbon spun fabric (CSF) as a substrate effectively enhances hydrogen generations due to sufficiently enlarged surface area. MoS2is grown on CSFs utilizing a hydrothermal method. Among three different MoS2coating morphologies depending on the amount of MoS2precursor and hydrothermal growth time, film shape MoS2on CSFs had the largest surface area, exhibiting the highest photocurrent density of 26.48 mA/cm2and the highest applied bias photon-to-current efficiency (ABPE) efficiency of 5.32% at 0.43 VRHE. Furthermore, with a two-step growth method of sputtering and a subsequent hydrothermal coating, continuous TiO2/MoS2heterojunctions on a porous CSF further promoted the photoelectrochemical performances due to their optimized bandgap alignments. Enlarged surface area, enhanced charge transfer, and utilization of visible light enable a highly efficient MoS2/TiO2/CSF photoanode with a photocurrent density of 33.81 mA/cm2and an ABPE of 6.97 % at 0.87 VRHE. The hydrogen generation amount of the PEC cell with MoS2/TiO2/CSF photoanode is 225.4 μmol/L after light irradiation of 60 s.

Despite the great interest in inorganic halide perovskites (IHPs) for a variety of photoelectronic applications, environmentally robust nanopatterns of IHPs have hardly been developed mainly owing to the uncontrollable rapid crystallization or temperature and humidity sensitive polymorphs. Herein, we present a facile route for fabricating environment- and phase-stable IHP nanopatterns over large areas. Our method is based on nanoimprinting of a soft and moldable IHP adduct. A small amount of poly(ethylene oxide) was added to an IHP precursor solution to fabricate a spin-coated film that is soft and moldable in an amorphous adduct state. Subsequently, a topographically prepatterned elastomeric mold was used to nanoimprint the film to develop well-defined IHP nanopatterns of CsPbBr3and CsPbI3of 200 nm in width over a large area. To ensure environment- and phase-stable black CsPbI3nanopatterns, a polymer backfilling process was employed on a nanopatterned CsPbI3. The CsPbI3nanopatterns were overcoated with a thin poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) film, followed by thermal melting of PVDF-TrFE, which formed the air-exposed CsPbI3nanopatterns laterally confined with PVDF-TrFE. Our polymer backfilled CsPbI3nanopatterns exhibited excellent environmental stability over one year at ambient conditions and for 10 h at 85 °C, allowing the development of arrays of two-terminal, parallel-type photodetectors with nanopatterned photoactive CsPbI3channels. Our polymer-assisted nanoimprinting offers a fast, low-pressure/temperature patterning method for high-quality nanopatterns on various substrates over a large area, overcoming conventional costly time-consuming lithographic techniques.

Environmentally friendly metal oxide quantum dot (QD) nanostructures have become attractive alternative materials for replacing QDs containing toxic elements of Cd and Pb. Although many attempts have been proposed for optoelectronic applications of hybrid metal oxide QDs with tailored opto-electronic properties, the fabrication of heterogeneous QD–fullerene hybrids as an emissive material has been studied little for optoelectronic devices. Herein, we report the preparation of ZnO–fullerene C70(ZnO–C70) QDs by a facile chemical reaction with a zero length linker and demonstrate whitish light-emitting diodes by fullerene induced multicolor emission from the ZnO–C70QD heterostructure. The electroluminescence (EL) is attributed to three new emission features in the visible region that originate from the electron transitions from three split lowest unoccupied molecular orbital levels of C70molecules to the valence band of ZnO QDs. Compared with photoluminescence, the EL emission was red-shifted by 50–130 meV due to the interaction between ZnO–C70QDs in the solid state. The energy levels of C70were also suitably aligned to those of ZnO QDs with a lower electron transfer barrier of 0.22 eV, which offers an advantageous route for electron transport. Consequently, the environmentally friendly ZnO–C70QDs with extraordinary properties promise great potential for use as novel encapsulating materials in the field of opto-electronic applications adopting QDs.

The emergence of transition metal carbides and nitrides (MXenes) addresses the rising demand for emerging yet favorable multifunctional materials for their utilization in flexible miniaturized electronics and beyond. However, MXenes pose a significant challenge due to their weak interfacial interactions, which result in inferior mechanical properties and structural integrity in MXene films. The continuous interfacial bridging approach involves incorporating hydrogen, ionic, and covalent bondings, and was developed to fabricate ultrastrong hydroxylated carbon nanotubes (HCNT) intercalated Ti3C2TxMXene (MX) films (MX@HCNT) with superior mechanical properties, electromagnetic interference (EMI) shielding performance, and thermal conductivity. The MX@HCNT films with hydrogen bonding between MX and HCNT were fabricated by vacuum filtration method and were further crosslinked by a conductive Fe3+ion (ionic bonding) and glutaraldehyde (GA, covalent bonding) molecules (MX@HCNT/Fe3+/GA). As a result, the continuous interfacial bridging approach facilitates the densification of MX nanosheets in the MX@HCNT/Fe3+/GA films. The resultant densified MX@HCNT/Fe3+/GA films with 50 wt% of HCNT exhibit significantly improved mechanical strength of 277 MPa, toughness of 5.5 MJ·m−3, EMI shielding effectiveness (EMI SE) of 71.9 dB, and an ultrahigh in-plane thermal conductivity of 106.8 W·m−1·K−1, making it effectively use in flexible devices.

This work reports on the in-situ chemical synthesis and their properties of multilayer graphene (MLG) shells, made by unzipping single walled carbon nanotubes (SWCNTs), on the surface of Zinc oxide (ZnO) core nanoparticles (NPs). The stable oxygen bridge bonds between the ZnO core and the oxygen-related functional groups on the MLG shells facilitate the efficient photoinduced charge separation. This charge separation mechanism is confirmed experimentally using time-correlated single photon counting (TCSPC) measurements. The calculated average carrier lifetimes of the ZnO@MLG NPs are approximately 102times faster than those for the bare ZnO NPs. The efficient electron transfer between the ZnO core and the MLG shell resulted in the significant improvement of the photocatalytic activity and the photoelectrochemical response. Simultaneously, the photocorrosion of ZnO was prevented by having the oxygen bridge bonds between the ZnO and MLG which suppressed the photo-generated holes oxidizing the surface oxygen atoms on ZnO, and in turn the holes are consumed by photocatalytic reaction. The 4.3 times enhanced photocurrent density at 0.2V vs. Ag/AgCl (pH 6.9) and around 10 times higher rate constant value of photodegradation of rhodamine B were achieved by ZnO@MLG NPs in comparison with those of bare ZnO NPs.

Recently, interfacial engineering approaches as an efficient strategy for improving the power conversion efficiencies (PCEs) of inverted polymer solar cells (iPSCs) has attracted considerable attention. Among various efficient solutions, solution-processed metal-oxide films prepared from metal oxide sol–gel precursors (or nanoparticles) and polymer surface modifiers are typically used as electron selective interfaces in the inverted cell geometry. To present a more effective strategy for surpassing the limitations of traditional methods, such as an unintended increase in series or contact resistance by incompatibility at the organic/inorganic interface, inherently insulating nature of non-conjugated surface modifiers and oxygen adsorption (or photo-induced doping) of metal-oxide layer, we synthesize chemically surface-modified ZnO@graphene core–shell type quantum dots (ZGQDs) with well-characterization of the chemical, optical and electrical properties, and fabricate iPSCs consisting of ITO/PEIE/ZGQD-OAs/photoactive layer/MoO3/Ag. The mono-layered QDs play the multi-functional role as surface modifier, sub-photosensitizer and electron transport layer. Using this effective approach, we achieve the highest conversion efficiency of ~10.3% resulting from improved interfacial properties and efficient charge transfer based on static quenching and charge transfer reaction from ZnO to graphene nanosheets (with drastically reduced τavg(~ 60ps)), which is verified by various analysis tools.

Two-dimensional van der Waals (2D vdWs) materials are a class of new materials that can provide important resources for future electronics and materials sciences due to their unique physical properties. Among 2D vdWs materials, black phosphorus (BP) has exhibited significant potential for use in electronic and optoelectronic applications because of its allotropic properties, high mobility, and direct and narrow band gap. Here, we demonstrate a few-layered BP-based nonvolatile memory transistor with a poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric top gate insulator. Experiments showed that our BP-based ferroelectric transistors operate satisfactorily at room temperature in ambient air and exhibit a clear memory window. Unlike conventional ambipolar BP transistors, our ferroelectric transistors showed only p-type characteristics due to the carbon–fluorine (C–F) dipole effect of the P(VDF-TrFE) layer, as well as the highest linear mobility value of 1159 cm2V–1s–1with a 103on/off current ratio. For more advanced memory applications beyond unit memory devices, we implemented two memory inverter circuits, a resistive-load inverter circuit and a complementary inverter circuit, combined with an n-type molybdenum disulfide (MoS2) nanosheet. Our memory inverter circuits displayed a clear memory window of 15 V and memory output voltage efficiency of 95%.

A conformal coating strategy with nanocarbon to enhance photoelectrochemical responses and the long-term stability of ZnO quantum dots is described. Strong anchoring bonds between a ZnO core and nanocarbon shell ameliorate the poor electrochemical stability of ZnO (such as photocorrosion) in liquid electrolyte. The conjugation of the graphene QD and C60to the ZnO QDs leads to 71% and 99% quenching of the UV photoluminescence (PL) emission, respectively. Also, the decay time of the nanocomposites at UV wavelengths measured much faster than that for the reference of bare ZnO QDs. The moderate energy states and good charge conductance of the nanocarbons result in ultrafast charge transport from the ZnO core to the nanocarbon shell. Thereby, the ZnO core–nanocarbon shell quantum dots shows significantly improved light harvesting performance. The PEC cell test for water oxidation and conventional degradation test using organic dyes exhibited that the photoelectrochemical activities could be significantly improved. At 1.23V (vs. RHE) in pH 6.9 electrolyte, 6 times enhanced photocurrent density was achieved by the conformal coating with C60(0.235mA/cm2for ZnO–C60photoanodes). In particular, the strong Zn–O–C bond structures on the ZnO surface prevented photoinduced holes from being consumed by the photocorrosion reaction of ZnO, thereby improving long-term stability.

Since the discovery of graphene, growth of two-dimensional (2D) nanomaterials has greatly attracted attention. However, spontaneous growth of atomic two-dimensional (2D) materials is limitedly permitted for several layered-structure crystals, such as graphene, MoS2, and h-BN, and otherwise it is notoriously difficult. Here we report the gas-phase 2D growth of silicon (Si), that is cubic in symmetry, viadendritic growth and an interdendritic filling mechanism and to form Si nanosheets (SiNSs) of 1 to 13 nm in thickness. Thin SiNSs show strong thickness-dependent photoluminescence in visible range including red, green, and blue (RGB) emissions with the associated band gap energies ranging from 1.6 to 3.2 eV; these emission energies were greater than those from Si quantum dots (SiQDs) of the similar sizes. We also demonstrated that electrically driven white, as well as blue, emission in a conventional organic light-emitting diode (OLED) geometry with the SiNS assembly as the active emitting layers. Tunable light emissions in visible range in our observations suggest practical implications for novel 2D Si nanophotonics.

Intensely pulsed white light (IPWL) treatment was tested as an ultrafast, large-area processable optical technique for the control of the nanostructure of a polymeric bulk-heterojunction photoactive layer to improve the efficiencies of polymer solar cells. Only 2 s of IPWL irradiation of a polymer:fullerene photoactive layer under ambient conditions was found to enhance significantly the power conversion efficiencies of the tested polymer solar cells to values approaching that of typical devices treated with thermal annealing. Consecutive white-light pulses from the xenon lamp induce the self-organization of the polymeric donor into an ordered structure and result in the optimized phase segregation of the polymeric donor and the fullerene acceptor in the photoactive layer, which enhances the light absorption and hole mobility and results in efficient photocurrent generation. The effects of varying the pulse conditions on device performance, including the irradiation fluence, pulse duration time, and number of pulses, were systematically investigated. Finally, it was successfully demonstrated that the IPWL treatment produces flexible polymer solar cells. The proposed IPWL process is suitable for the efficient industrial roll-to-roll production of polymer solar cells.

The effect of electrode materials on resistance switching was evaluated on the Pt/NiO/electrode (EL) structures where the EL contacts were Pt, Al, and indium--tin-oxide (ITO). It was confirmed that ohmic Pt contact needs to induce the effective electric field for resistance switching across the NiO film. For the Pt/NiO/Al structure, the barrier height of the Al Schottky contact was measured as 0.66 eV and no resistance switching was observed owing to a large voltage drop at the rectifying interface induced by the reduction of NiO resulting from the formation of Al oxide. In the ITO (EL)/NiO/Pt structure, the barrier height of the Schottky contact between ITO and NiO was about 0.52 eV and it did not show any resistance switching, either. Through the depth-profile study by X-ray photoelectron spectroscopy, chemical reactions at the interface ITO/NiO was identified to be not too much evolved compared with that of NiO/Al, which might due to be abundant oxygen on the ITO surface. Such Schottky barrier heights 0.52--0.66 eV were considered too high to induce a sufficient electric field in the NiO film causing the resistance switching.

We report on the identification of molecular orientation and its order–disorder transition during the initial growth of 1,3-bis(N-carbazolyl)benzene (mCP) thin films on a highly ordered pyrolytic graphite (HOPG) surface by using photoelectron spectroscopy (PES). Theoretical PES amplitudes using a quantum mechanical calculation that adapts independent atomic center approximation (IAC) were calculated to compare with experimental observations. At low coverage, an equilibrium orientation of isolated adsorbate was estimated. As the coverage increases, the interaction between adsorbates becomes dominant and raises the disorder, which results in changes in the PES shapes as well as the line broadening of each peak.

We report on the nonvolatile memory characteristics of a bistable organic memory (BOM) device with Au nanoparticles (NPs) embedded in a conducting poly(N-vinylcarbazole) (PVK) colloids hybrid layer deposited on flexible poly(ethyleneterephthalate) (PET) substrates. Transmission electron microscopy (TEM) images show the Au nanoparticles distributed isotropically around the surface of a PVK colloid. The average induced charge on Au nanoparticles, estimated using the C−Vhysteresis curve, was large, as much as 5 holes/NP at a sweeping voltage of ±3 V. The maximum ON/OFF ratio of the current bistability in the BOM devices was as large as 1 × 105. The cycling endurance tests of the ON/OFF switching exhibited a high endurance of above 1.5 × 105cycles, and a high ON/OFF ratio of ∼105could be achieved consistently even after quite a long retention time of more than 1 × 106s. To clarify the memory mechanism of the hole-mediated bistable organic memory device, the interactions between Au nanoparticles and poly(N-vinylcarbazole) colloids was studied by estimating the density of states and projected density of state calculations using density functional theory. Au atom interactions with a PVK unit decreased the band gap by 2.96 eV with the new induced gap states at 5.11 eV (HOMO, E0) and LUMO 4.30 eV and relaxed the HOMO level by 0.5 eV (E1). E1at ∼6.2 eV is very close to the pristine HOMO, and thus the trapped hole in E1could move to the HOMO of pristine PVK. From the experimental data and theoretical calculation, it was revealed that a low-conductivity state resulted from a hole trapping at Eoand E1states and subsequent hole transportation through Fowler−Nordheim tunneling from E1state to Au NPs and/or interface trap states leads to a high conductivity state.

Zero- and one-dimensional metal nanocrystals were successfully fabricated with accurate control in size, shape, and position on semiconductor surfaces by using a novel in situfabrication method of the nanocrystal with a biasing tungsten tip in transmission electron microscopy. The dominant mechanism of nanocrystal formation was identified mainly as local Joule heating-assisted electromigration through the direct observation of formation and growth processes of the nanocrystal. This method was applied to extracting metal atoms with an exceedingly faster growth rate (∼105atoms/s) from a metal-oxide thin film to form a metal nanocrystal with any desired size and position. By real-time observation of the microstructure and concurrent electrical measurements, it was found that the nanostructure formation can be completely controlled into various shapes such as zero-dimensional nanodots and one-dimensional nanowires/nanorods.

Polystyrene Petri dishes were modified by an ion-assisted reaction to supply a suitable surface for culturing cells. Wettability was measured by a contact anglometer after surface modification of polystyrene. Contact angles of water on the polystyrene were not reduced much by Ar⁺ ion irradiation only, but dropped rapidly to a minimum of 19°, when polystyrene surface was modified by Ar⁺ ion irradiation with flowing oxygen gas. X-ray photoelectron spectroscopy analyses showed that hydrophilic groups were formed on the surface of polystyrene by a chemical reaction between unstable chains induced by the ion irradiation and the blown oxygen gas. Newly formed hydrophilic groups were identified as C&bond;O, &bond;(C&dbond;O)&bond; and &bond;(C&dbond;O)&bond;O&bond; bonds. The influence of the ion beam modification in growth of the rat pheochromocytoma cells was investigated. The results showed exclusively preferential cell growth in the polystyrene Petri dish that was treated by the ion-assisted reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 41–46, 1999

Polyvinylidenefluoride (PVDF) was irradiated by a keV Ar⁺ ion in O2 environment for improving adhesion between PVDF and Pt, and reaction between PVDF and the ion beam has been investigated by X-ray photoelectron spectroscopy (XPS). The adhesion test between Pt and the modified PVDF was carried out by boiling test, in which the specimens were kept in boiling water for 4 h. Two failure modes (buckling up due to weak adhesion and crack formation due to strong adhesion) of Pt films have been observed in the system. Contact angle of PVDF was reduced to 31 from 75° by the irradiation of 1 × 10¹⁵ Ar⁺ ions/cm² with oxygen flow rate of 8 sccm. The surface of the irradiated PVDF became more rough as ion dose increased. The improved adhesion mechanism and identification of newly formed chemical species have been confirmed by Carbon 1s and Fluorine 1s X-ray photoelectron core-level spectra. The main reaction occurred at the irradiated PVDF surface is an ion-beam-induced oxidation accompanied with preferential sputtering of fluorine. Newly formed chemical species at interface are regarded as ester and carboxyl groups. Adhesion of the Pt–PVDF interface was improved by ion irradiation in O2 environment. This improvement is originated from the presence of carbon—oxygen bonds on the irradiated PVDF surface. Comparison of failure modes on the irradiated PVDF at various conditions after the boiling test shows that adhesion of Pt film is largely affected by the product of ion-assisted reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 41–47, 1999

A surface of thin square polytetrafluoroethylene (PTFE) samples (1 × 1 × 0.2 cm³) was irradiated with Ar⁺ at 1 keV with varying ion dose from 5 × 10¹⁴ to 1 × 10¹⁷ ions/cm² with and without an oxygen environment. The irradiated surface of the samples was examined by scanning electron microscopy (SEM) for surface textural changes and x-ray photoelectron spectrometry (XPS) for changes in chemical structure. A wettability test was conducted on the irradiated surface of PTFE samples by water droplets. A Scotch ™ tape adhesion test, after a thin film of Cu or Al was evaporated on the irradiated surface, and a tensile test after irradiated samples were glued to sample holders by an adhesive glue (Crystal Bond) was also run. The SEM micrographs showed increasing roughness with fiber forest-like texture with increasing ion dose. The Ar⁺ with an O2 environment produced finer and denser fiber forest-like texture than that without O2. The high-resolution XPS spectra showed decreased intensity of the F1s peak and formation of the O1s peak when irradiated with the O2 environment. The increase of the O1s peak may be attributed to the reaction of oxygen atoms and the free radicals created by Ar⁺ bombardment. The wettability of water droplets on the irradiated surfaces was found to be inversely proportional to the surface roughness. Adhesion tests were conducted on 2000 Å thick Al or Cu film. Full detachment of the metal films was observed when PTFE samples were not modified. Partial detachment of the Al film occurred when PTFE was irradiated without the O2 environment, regardless of ion dose. No detachment of the film occurred when PTFE was irradiated with the O2 environment with the ion dose exceeding 1 × 10¹⁶ ions/cm². Partial detachment of Cu film was observed with or without the O2 environment when the ion dose was 5 × 10¹⁴ ions/cm². No detachment occurred with or without the O2 environment when the ion dose was 1 × 10¹⁵ ions/cm² or greater. The tensile test showed that adhesion of an adhesive cement (Crystal Bond) to the irradiated PTFE samples increased significantly with increasing ion dose up to 1 × 10¹⁶ ions/cm². Possible mechanisms for the improved adhesion are given. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1913–1921, 1997

Simple solution spray coating of graphene oxide (GO) and Ag nanowires (AgNWs) was employed to prepare transparent conductive films (TCFs). We used air and ultrasonic spraying, and the effects of different spraying methods on the properties of TCFs were investigated. Ultrasonic spraying exhibited a significant decrease in the length of AgNWs and increase of sheet resistance. Thin two-dimensional reduced graphene oxide (rGO) prepared by ultrasonic spraying with tightly bound conductive Ag nanowires prepared by air spraying effectively decreased the sheet resistance and increased the transparency of the hybrid films. Air-sprayed rGO (0.25 mL)–AgNW (0.45 mL)/poly(methyl methacrylate) exhibited a sheet resistance of 328 Ω/; however, the ultrasonic-sprayed rGO (0.25 mL)–air-sprayed AgNW (0.45 mL) on a poly(methyl methacrylate) showed a significant improvement of sheet resistance to 86 Ω/ with a light transmittance of 78%. The sprayed rGO–AgNW showed little change in sheet resistance after 200 bending cycles with a radius curvature of 10 mm.

A hybrid polymer-quantum dots (QDs) white light-emitting diode (WLEDs) device with a multi-layer structure by all solution processing is simply fabricated by using a spin coating technique. From transmission electron microscopy (TEM) study, red--green--blue (RGB) CdSe/ZnS QDs are mainly distributed along with the circumference of poly(N-vinylcarbazole) (PVK) surfaces, resulting in core--shell hybrid polymer-QDs of [RGB CdSe/ZnS QDs]/PVK. The Al/Cs2CO3/[RGB CdSe/ZnS QDs+PVK]/poly[(N,N$\aku '$-bis(4-butylphenyl)-N,N$\aku '$-bis(phenyl)benzidine)] (poly-TPD)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/indium--tin-oxide (ITO)/glass WLEDs shows electroluminescence (EL) centered at around 474, 544, and 629 nm with CIE coordinates, $(0.44,0.32)$ at the forward bias +11 V, which clearly reveals that CdSe/ZnS QDs existing at the interface between PVK plays as a recombination center of exciton.

Lead sulfide (PbS) quantum dots (QDs) have great potential in optoelectronic applications because of their desirable characteristics as a light absorber for near-infrared (NIR) photodetection. However, most PbS-based NIR photodetectors are two-terminal devices, which require an integrated pixel circuit to be practical photosensors. Here we report on PbS QD/indium gallium zinc oxide (InGaZnO, IGZO) metal oxide semiconductor hybrid phototransistors with a photodetection capability between 700 and 1400 nm, a range that neither conventional Si nor InGaAs photodetectors can cover. The new hybrid phototransistor exhibits excellent photoresponsivity of over 106 A W−1and a specific detectivity in the order of 1013 Jones for NIR (1000 nm) light. Furthermore, we demonstrate an NIR (1300 nm) imager using photogating inverter pixels based on PbS/IGZO phototransistors at an imaging frequency of 1 Hz with a high output voltage photogain of ~4.9 V (~99%). To the best of our knowledge, this report demonstrates the first QD/metal oxide hybrid phototransistor-based flat panel NIR imager. Our hybrid approach using QD/metal oxide paves the way for the development of gate-tunable and highly sensitive flat panel NIR sensors/imagers that can be easily integrated.

We fabricated the organic photovoltaic (OPV) cells on the transparent and low resistive multilayer electrode of a few nm Ag layer embedded Al doped zinc oxide film (AZO/Ag/AZO) on a glass. AZO and Ag consisting of the continuous multilayer were fabricated using rf magnetron at room temperature successively. AZO (45 nm)/Ag (11 nm)/AZO (45 nm) electrode shows an electrical resistivity of $6.56\times 10^{-5}$ $\Omega$ cm, optical transmittance of 89.3% at 550 nm and figure of merit (FOM) value of $4.94\times 10^{-2}$ $\Omega^{-1}$. An inverted structure OPV was fabricated on AZO/Ag/AZO transparent electrode in which TiOxand PEDOT:PSS were used as an electron transport and hole transport layer respectively. The OPVs showed power conversion efficiency and fill factor as high as 2.07%, 0.51 respectively.

The study on the influences of ZrO2addition in LiMn2O4thin films as cathodes was driven by the need to improve the physical and electrochemical performances of thin-film lithium batteries. The films of xZrO2–LiMn2O4at x=0.025possessed a high capacity retention of 82%at 4C after 130 cycles, compared to 68% at x=0, due to the formation of amorphous ZrO2on the grain boundary and surface out of the LiMn2O4matrix via the pulsed laser deposition. The ZrO2modification decreased the charge-transfer resistance (Rct)and unwanted phase transition of the LiMn2O4cathode film.

Perovskite manganite La-Ca-Mn-O (LCMO) thin films were deposited on LaAlO3(001) single crystal substrate by radio-frequency magnetron sputtering at room temperature. After annealing at 800-1000°C in O2atmosphere for 1 h, sheet resistance (R) of the LCMO thin films was measured by van der Pauw method in the range of 77-300 K. The characteristic resistance-temperature curves of all the annealed films showed typical insulator to metal transition behavior of colossal magnetoresistance (CMR) materials on cooling. The sheet resistance of LCMO films changes with temperature, conforming to a function of exp (?T) in the temperature range from 77 K to 230 K, which is applicable to an oxide thin film thermistor.

High-quality ZnO film and highly wettable polymethylmethacrylate (PMMA) are obtained by using a keV ion beam. ZnO films are grown on glass substrates by ion beam sputter deposition, changing the oxygen/argon gas ratio, ion beam energy, and substrate temperature. Physical properties of ZnO films were investigated by X-ray diffraction, Rutherford backscattering spectroscopy, and the Van der Pauw method. All the films show a strong preferred orientation along the c-axis. The electrical resistivity is varied from 10-3to 106?cm and its dependence on the deposition parameters is discussed. The PMMA surface was modified by the ion-assisted reaction technique. Ion dose, ion energy, and oxygen gas flow rate are varied from 5×1015to 1×1017ions/cm2, from 0.6 to1.2 kV, and from 0 to 8 ml/min, respectively. A highly wettable PMMA surface can be obtained by irradiating oxygen ions in an oxygen gas environment. X-ray photoelectron spectroscopic analysis shows that hydrophilic groups are formed on the surface of PMMA.

In the present paper the possibility of application of the regularization method for reliable determination of the position and form of structural features of electron energy distribution is considered. The regularization method is used in the processing of the probe characteristics, measured in gas discharge chambers of broad beam gridded Xe ion sources, with peripheral and with divergent magnetic fields, as well as in an ion accelerator with closed electron drift. Electron energy distribution functions with secondary maxima are observed in the plasma devices.

In order to accurately determine the oxidation state of tin and to investigate the chemical shifts between tin and its oxides, quantitative Auger electron spectroscopy and X-ray photoelectron spectroscopy studies were performed using Sn metal, stoichiometric SnO2powder, and polycrystalline SnOxthin films. Films with different oxygen contents were grown using a reactive ion-assisted deposition technique. As the atomic ratio of tin to oxygen in the deposited films increased to the stoichiometric value of 2, the tin M4N4,5N4,5Auger transition and the corresponding Sn 3d5/2core-level photoelectron line gradually shifted to lower kinetic energy and higher binding energy by as much as 6±1 eV and 2.39±0.02 eV, respectively, relative to those of the tin metal. An explanation for the observed systematic difference between the chemical shifts of Auger and photoelectron lines is given. It is based on the difference in electronic polarization energy between the final two-hole state produced by the Auger electron emission and the final single-hole state produced by the photoelectron emission.

Tin oxide ( SnOx) thin films were deposited by ion-assisted deposition (IAD) at various ion beam voltages (VI) onto amorphous SiO2/Si substrate at room temperature. Tin oxide thin films with nonstoichiometric/stoichiometric composition were fabricated. The as-deposited SnOxfilms were mostly amorphous, but they exhibited various degrees of crystallinity and fine grain size after annealing at 500° C for 1 h in air. The annealed film deposited using an ion beam energy (EI) of 300 eV showed a preferred orientation along the SnO2(110) plane. The preferred orientation changed to SnO2(002) for film 1000 (the annealed film deposited with EI=1000 eV) through an amorphous intermediate structure of film 500 (the annealed film deposited with EI=500 eV). X-ray photoelectron spectroscopy study showed that the main Sn3dpeaks in all samples were similar to the binding energy of Sn4+and the atomic ratios for all the films were higher than 1.51. For the film grown under an average energy of 123 eV/atom, the refractive index was 2.0 and the estimated porosity was 5.2% smaller than that of the other films.