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New ether-substituted poly(1,4-phenylene vinylene) (PPV) derivatives were synthesized via Horner–Emmons coupling. The structures of the monomers and the resultant oligomers were confirmed by 1H and 13C NMR spectroscopies. The molecular weights of the oligomers were characterized by gel permeation chromatography, giving the number-average and weight-average molecular weights and the corresponding polydispersity indices. Measurements of UV–vis absorption and fluorescence were used to characterize the optical properties of the oligomers. Estimation of the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels and other electrochemical characteristics of the oligomers were investigated by cyclic voltammetry. Dialkyl and dialkoxy PPV oligomers were also prepared and characterized following the same instrumental methods used for the ether-substituted oligomers, providing a known reference system to judge the performance of the new conjugated oligomers. Devices were fabricated to analyze the electroluminescent characteristics of the oligomers in organic light-emitting diodes.

Large arrays of nanoscale silicon field emitters are tested in a UHV system equipped with a phosphor screen. The anode current is measured and the emission pattern is captured at the same time. The emission pattern shows the whole Field Emission Arrays (FEAs) are emitting from the beginning of the test. But as the test progresses, the regions at the edge of the array are more vulnerable and tend to be damaged/shorted first. A few shorted emitters along the edges could reduce the effective gate bias applied to the central region of the array, causing the emission current of the whole array to drop dramatically, and prompt the FEA to fail, while the physical integrity of majority emitters in the array are intact.

A newer model for diffraction from a Digital Micromirror Device is disclosed. The model predicts an improvement in light throughput, when the micromirrors are addressed in a FLAT state distinct from the standard ON/OFF states.

Reconfigurable beam steering components are indispensable to support optical and photonic network systems operating with high adaptability and with various functions. Currently, almost all such components are made of solid parts whose structures are rigid, and hence their functions are difficult to be reconfigured. Also, optical concentration beam steering is still a very challenging problem compared to radio frequency/microwave steering. Here we show a watermill-like beam steering system that can adaptively guide concentrating optical beam to targeted receivers. The system comprises a liquid droplet actuation mechanism based on electrowetting-on-dielectric, a superlattice-structured rotation hub, and an enhanced optical reflecting membrane. The specular reflector can be adaptively tuned within the lateral orientation of 360°, and the steering speed can reach ~353.5° s−1. This work demonstrates the feasibility of driving a macro-size solid structure with liquid microdroplets, opening a new avenue for developing reconfigurable components such as optical switches in next-generation sensor networks. Adaptive elements for optical beam steering are increasingly important to support nascent optical and photonic networks. This work presents a beam steering device based on a liquid droplet actuation method, capable of providing 360 degrees lateral steering with low energy consumption and a fast response time.

We propose the use of polysilicon thin-film circuits to develop charged particle and neutron detection systems. We detail the methodology to design, fabricate, and implement polysilicon preamplifiers with the requirements for radiation detectors. We demonstrate the combination of polysilicon electronics with Si photodiodes to resolve the spectral response of a 210Po alpha source and demonstrate for the first time neutron detection capabilities. Also, we present the first implementation of a full thin-film radiation detection system using CdS/CdTe detectors and a polysilicon thin-film transistor for single-event charged particle detection.

The thermal stability and contact resistance of TaAlN thin films as electrical contacts to SiGe thermoelectric elements are reported. We demonstrate that a sharp interface is maintained after the device annealed at 800 °C for over 100 h, indicating that no interdiffusion takes place between TaAlN and SiGe. A specific contact resistivity of (2.1 ± 1.3) × 10−6 Ω-cm2 for p-type SiGe and (2.8 ± 1.6) × 10−5 Ω-cm2 for n-type SiGe is demonstrated after the high temperature annealing. These results show that TaAlN is a promising contact material for high temperature thermoelectrics such as SiGe.

Thin-film Mg 2 Si was deposited using radio frequency (RF) magnetron sputtering. Al and Sn were incorporated as n-type dopants using co-sputtering to tune the thin-film electrical properties. X-ray diffraction (XRD) analysis confirmed that the deposited films are polycrystalline Mg 2 Si. The Sn and Al doping concentrations were measured using Rutherford backscattering spectroscopy (RBS) and energy dispersive X-ray spectroscopy (EDS). The charge carrier concentration and the charge carrier type of the Mg 2 Si films were measured using a Hall bar structure. Hall measurements show that as the doping concentration increases, the carrier concentration of the Al-doped films increases, whereas the carrier concentration of the Sn-doped films decreases. Combined with the resistivity measurements, the mobility of the Al-doped Mg 2 Si films is found to decrease with increasing doping concentration, whereas the mobility of the Sn-doped Mg 2 Si films is found to increase.

We present a detailed study of post-deposition annealing effects on contact resistance of Au, Ti, Hf and Ni electrodes on Mg 2 Si thin films. Thin-film Mg 2 Si and metal contacts were deposited using magnetron sputtering. Various post-annealing temperatures were studied to determine the thermal stability of each contact metal. The specific contact resistivity (SCR) was determined using the Cross Bridge Kelvin Resistor (CBKR) method. Ni contacts exhibit the best thermal stability, maintaining stability up to 400 °C, with a SCR of approximately 10 −2 Ω-cm 2 after annealing. The increased SCR after high temperature annealing is correlated with the formation of a Mg-Si-Ni mixture identified by cross-sectional scanning transmission electron microscopy (STEM) characterization, X-ray diffraction characterization (XRD) and other elemental analyses. The formation of this Mg-Si-Ni mixture is attributed to Ni diffusion and its reaction with the Mg 2 Si film.

Visible light communication (VLC) systems can achieve a higher data rate by increasing the number of channels using wavelength division multiplexing (WDM) technology. In this paper, we investigate the maximum number of channels and possible data rate in a WDM-VLC system based on light emitting diode (LED). Channel crosstalk from the spectral overlap of LEDs is analyzed by modeling LED spectra and the formula for crosstalk is derived from VLC link, including optical filter transmittance and detector spectral response. An experimental setup with different wavelength of LEDs is used to confirm the validity of the crosstalk analysis. The number of channels and data rate are determined by the SNR, including signal power, channel crosstalk, and detector noise. The results indicate that for indoor illumination standard with on – off keying modulation and 33 nm channel spacing to achieve a BER of $10^{- 6}$ , the maximum and optimal numbers of channels are 12 and 10, respectively. Additionally, the achievable data rate is 5.1 Gb/s which is about 9.3 times than that of the single channel system.

Solid-state neutron detectors offer an alternative to 3He based detectors, but suffer from limited neutron efficiencies that make their use in security applications impractical. Solid-state neutron detectors based on single crystal silicon also have relatively high gamma-ray efficiencies that lead to false positives. Thin film polycrystalline CdTe based detectors require less complex processing with significantly lower gamma-ray efficiencies. Advanced geometries can also be implemented to achieve high thermal neutron efficiencies competitive with silicon based technology. This study evaluates these strategies by simulation and experimentation and demonstrates an approach to achieve >10% intrinsic efficiency with

Organic and inorganic thin film transistors (TFTs) are fabricated, simulated, and tested for circuit applications. The devices are based on polycrystalline cadmium sulfide (CdS) and pentacene thin films. Both devices are simulated and analyzed using two-dimensional finite element simulation methodology. For CdS, grain boundary and uniform trap distribution approaches are implemented. It is assumed that traps due to grain boundaries are uniformly distributed throughout the film. For pentacene a Poole-Frenkel mobility model is employed. After matching device simulation with experimental data, the SPICE model parameters are extracted for circuit simulation. The devices are tested for both analog and digital circuits. operational amplifier (OPAMP) and inverter circuits are tested. Two OPAMP topologies are compared and the results are discussed. One of the topologies is based on all n-type transistors using CdS TFT and the other topology is the two-stage Miller compensated CMOS design based on CdS and pentacene TFTs. The operational amplifiers have an open-loop voltage gain of 25.9dB and 29.7dB respectively. The performance of the CMOS design is found to be limited by performance of pentacene transistor. Display Omitted

Microelectrode arrays (MEAs) enable non-invasive recording of supra-threshold signals, i.e. action potentials or spikes, from a variety of cultured electrically active cells. While this label-free technology has been shown to be useful for pharmacological and toxicological studies, a major limitation has been the reliance on expensive recording substrates that have been manufactured with the intent of re-use. Prior work by our group has demonstrated an approach for fabricating MEAs using conventional liquid crystal display manufacturing techniques. Here, we describe and characterize the UT Dallas planar MEA which is fabricated with low cost materials and processes. We compare the performance of the UT Dallas MEAs, which consist of exposed gold microelectrodes with patterned parylene insulation over traces, with well-established commercially available MEAs using cultured murine cortical networks. Detailed electrophysiological comparisons show virtually identical performance between MEA types with respect to network metrics including recording yield across the array, network spike rate and burst rate, and virtually identical pharmacological responses to a diverse set of neuropharmacological agents.

Substrate-integrated microelectrode arrays (MEAs) are non-invasive platforms for recording supra-threshold signals, i.e. action potentials or spikes, from a variety of cultured electrically active cells, and are useful for pharmacological and toxicological studies. However, the MEA substrate, which is often fabricated using semiconductor processing technology, presents some challenges to the user. Specifically, the electrode encapsulation, which may consist of a variety of inorganic and organic materials, requires a specific substrate preparation protocol to optimize cell adhesion to the surface. Often, these protocols differ from and are more complex than traditional protocols for in vitro cell culture in polystyrene petri dishes. Here, we describe the fabrication of an MEA with indium tin oxide microelectrodes and a patterned polystyrene electrode encapsulation. We demonstrate the electrochemical stability of the electrodes and encapsulation, and show viable cell culture and in vitro recordings.

We compute thermal conductivity ( κ ) of magnesium silicide (Mg 2 Si) with point defects and nanoparticles through molecular dynamics simulation. To describe an alloy with complex defect structures, the extended modified embedded atom method is utilized in this simulation study. The calculated phonon dispersion and κ of pristine Mg 2 Si are in close agreement with first-principles calculations and experimental results. We compared the effect of intrinsic point defects and nanoparticles on heat transfer in Mg 2 Si at the same stoichiometry. We find that point defects could be more effective than nanoparticles to reduce κ . The geometric size effect is also investigated for Mg and Si nanoparticles. Smaller Mg nanoparticles can significantly reduce κ . However, Si nanoparticles demonstrate little size effect on κ . Our simulation results show that phonon transport in Mg 2 Si has more contribution from strain scattering than mass defect scattering. These findings can provide guidance for experiments to more effectively engineer bulk Mg 2 Si with nanostructured defects for thermoelectric applications.

By using a single host for both blue and orange phosphorescent dopants, a simple and efficient white organic light emitting-diode is reported. The dual-emissive-layer white device achieves a peak external quantum efficiency of 16.9 ± 0.9% and power efficiency of 44.1 ± 2.3 lm/W without out-coupling enhancement. Analysis of the device working mechanism determines that the blue dopant molecules can form a bridge to facilitate electron transport into the adjacent orange emitting-layer. The orange emission originates from both the direct electron trapping by the orange dopant and incomplete blue–orange energy transfer mechanisms. The origin of the voltage-dependent color shift of the device is quantitatively determined according to the working mechanism. Possible solution to reducing the color-shift is also provided based on the calculation and analytical results.

This articles in this special issue on flexible hybrid electronics provides insight into the technical problems that must be overcome as well as the new capabilities they will provide. The term, 'flexible hybrid electronics' means different things based on the context in which it is being discussed. It could mean adaptable for multiple applications, but, here the term refers to mechanical properties, although not necessarily precisely defined. Mechanically flexible might mean anything from conformable (nonlinear shape) to bendable or rollable (around a defined radius of curvature), or even foldable and stretchable. Although not well defined, the intent is to differentiate from the rectangular, rigid form factor of conventional semiconductor electronics. Hybrid means heterogeneous integration of conventional electronics with other electronic components (passive devices, sensors, etc.) that could be fabricated using conventional thin-film transistor (TFT) process technology by additive printing (ink jet, gravure, etc.). The purpose is to provide an electronics solution that has adequate performance, but in a low cost, novel form factor because printing offers the ability to inexpensively fabricate structures over large areas on mechanically flexible substrates (plastics, metal sheets, bendable glass). However, integration with conventional electronics such as silicon CMOS is necessary to achieve required performance because TFT and printed devices are ignificantly inferior to conventionally fabricated devices.

The electronic structure of group VA impurities in PbTe is investigated by first principles calculations. Our findings show that these impurities can act as either donors or acceptors, depending on whether they occupy Pb or Te lattice sites. The impurities introduce a defect state at ∼0.3 eV above the conduction band minimum if they stay at Pb sites, whereas they introduce a state at the edge of the PbTe valence band if they stay at Te sites. The implications of our calculations on the thermoelectric efficiency of PbTe are also discussed.

Four new donor–acceptor copolymers were synthesized by using benzo[1,2-b:4,5-b′]dithiophene and benzo[1,2-b:4,5-b′]difuran as donors and thieno[3,4-b]thiophene was used as the acceptor building block. A systematic study was performed to determine the influence of the combinations of different heteroatoms in the donor–acceptor copolymer. In bulk heterojunction solar cells, the polymer with all furan building blocks in the electron donating units, poly[(4,8-bis(5-dodecyl-2-furanyl)benzo[1,2-b:4,5-b′]difuran-2-yl)-alt-(2-ethyl-1-(3-fluorothieno[3,4-b]thiophen-2-yl)-1-hexanone)] (P4) (Mn = 66.7 kDa), achieved the highest power conversion efficiency of 5.23%.

The sputtering of Mo Spindt emitter due to the gate absorbent are observed when nA level emission current is collected by the gate for a duration of tens of seconds under a vacuum of 1×10−7 Torr.

We have demonstrated a low temperature fully integrated process for a ferroelectric random access memory array for potential flexible electronics applications. The memory cell is based on a two-transistor-two-capacitor structure, with cadmium sulfide as the semiconductor material for n-channel thin-film transistors, and poly(vinylidene fluoride-trifluoroethylene) copolymer as the ferroelectric material for capacitors. At VDD = 5 V, a voltage difference of ~1 V between the two states (0 and 1) is achieved at the output of the sense amplifier.

The demonstrated square-planar Pt(II)-complex has reduced triplet-triplet quenching and therefore a near unity quantum yield in the neat thin film. A non-doped phosphorescent organic light-emitting diode (PhOLED) based on this emitter achieves (31.1 ± 0.1)% external quantum efficiency without any out-coupling, which shows that a non-doped PhOLED can be comparable in efficiency to the best doped devices with very complicated device structures.

The effect of a polycrystalline silicon (poly-Si) seeding layer on the properties of relaxor Pb(Zr0.53,Ti0.47)O3–Pb(Zn1/3,Nb2/3)O3 (PZT–PZN) thin films and energy-harvesting cantilevers was studied. We deposited thin films of the relaxor on two substrates, with and without a poly-Si seeding layer. The seeding layer, which also served as a sacrificial layer to facilitate cantilever release, was found to improve morphology, phase purity, crystal orientation, and electrical properties. We attributed these results to reduction of the number of nucleation sites and, therefore, to an increase in relaxor film grain size. The areal power density of the wet-based released harvester was measured. The power density output of the energy harvester with this relaxor composition and the poly-Si seeding layer was 325 μW/cm2.

An experimental and computational study of correlations between solid-state structure and optical/electronic properties of cyclotrimeric gold(I) carbeniates, [Au3(RN═COR')3] (R, R' = H, Me, (n)Bu, or (c)Pe), is reported. Synthesis and structural and photophysical characterization of novel complexes [Au3(MeN═CO(n)Bu)3], [Au3((n)BuN═COMe)3], [Au3((n)BuN═CO(n)Bu)3], and [Au3((c)PeN═COMe)3] are presented. Changes in R and R' lead to distinctive variations in solid-state stacking, luminescence spectra, and conductive properties. Solid-state emission and excitation spectra for each complex display a remarkable dependence on the solid-state packing of the cyclotrimers. The electronic structure of [Au3(RN═COR')3] was investigated via molecular and solid-state simulations. Calculations on [Au3(HN═COH)3] models indicate that the infinitely extended chain of eclipsed structures with equidistant Au--Au intertrimer aurophilic bonding can have lower band gaps, smaller Stokes shifts, and reduced reorganization energies (λ). The action of one cyclotrimer as a molecular nanowire is demonstrated via fabrication of an organic field effect transistor and shown to produce a p-type field effect. Hole transport for the same cyclotrimer-doped within a poly(9-vinylcarbazole) host-produced a colossal increase in current density from ∼1 to ∼1000 mA/cm(2). Computations and experiments thus delineate the complex relationships between solid-state morphologies, electronic structures, and optoelectronic properties of gold(I) carbeniates.

Today's state-of-the-art phosphorescent organic light-emitting diodes (PhOLEDs) must rely on the host-guest doping technique to decrease triplet quenching and increase device efficiency. However, doping is a sophisticated device fabrication process. Here, a Pt(II)-based complex with a near unity photoluminescence quantum yield and excellent electron transporting properties in the form of neat film is reported. Simplified doping-free white PhOLED and yellow-orange PhOLED based on this emitter achieve rather low operating voltages (2.2–2.4 V) and very high power efficiencies of approximately 80 lm W−1 (yellow-orange) and 50 lm W−1 (white), respectively, without any light extraction enhancement. Furthermore, the efficient white device also exhibits high color stability. No color shift is observed during the entire operation of the device. Analysis of the device's operational mechanism has been postulated in terms of exciton and polaron formation and fate. It is found that using the efficient neat Pt(II)-complex as a homogeneous emitting and electron transporting layer and an ambipolar blue emitter are determining factors for achieving such a high efficiency.

The performance of graphene field effect transistors fabricated on flexible substrates is easily degraded by deformation, delamination and shrinkage during the device fabrication. Multiple thermal annealing on graphene devices could be performed without damages to the flexible substrate using a rigid supporting substrate, poly(dimethylsiloxane) coated Si, holding the flexible substrate during the device fabrication. As a result, a very high performance including electron mobility ∼12980 and hole mobility ∼9214 cm2/Vs could be achieved. The performance enhancement is attributed to the effective removal of polymer residues using a high temperature vacuum anneal and a reduced interfacial reaction between the graphene and the hydrophobic flexible substrate.

In this work thin CdS films using glycine as a complexing agent were fabricated by chemical bath deposition and then doped with silver (Ag), by an ion exchange process with different concentrations of AgNO 3 solutions. The CdS films were immersed in silver solutions using different concentrations during 1 min for doping and after that the films were annealed at 200 °C during 20 min for dopant diffusion after the immersion on the AgNO 3 solutions. The aim of this research was to know the effects of different concentrations of Ag on the optical and structural properties of CdS thin films. The optical band gap of the doped films was determined by transmittance measurements, with the results of transmittance varying between 35% and 70% up to 450 nm in the electromagnetic spectra and the band gap varying between 2.31 and 2.51 eV depending of the silver content. X-ray photoelectron spectroscopy was used to study the influence of silver on the CdS:Ag films, as a function of the AgNO 3 solution concentration. The crystal structure of the thin CdS:Ag films was studied by the X-ray diffraction method and the film surface morphology was studied by atomic force microscopy. Using the ion exchange process, the CdS films’ structural, optical and electric characteristics were modified according to silver nitrate concentration used.

Poly{4,8-bis(95-dodecylthiophene-2-yl)benzo[1,2-b:4,5-b′]dithiophene} has been synthesized by both Grignard metathesis (P1) and Stille coupling polymerizations (P2). Polymers P1 and P2 were characterized and their optoelectronic properties, charge carrier mobilities, and photovoltaic properties were compared. The field-effect mobilities of the polymers were measured on both untreated and heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane (FS) treated organic field effect transistor (OFET) devices. The polymers were also evaluated in bulk heterojunction (BHJ) solar cells with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor.

An ideal microelectrode array (MEA) design should include materials and structures which exhibit biocompatibility, low electrode polarization, low impedance/noise, and structural durability. Here, the fabrication of MEAs with indium tin oxide (ITO) electrodes deposited with self-similar gold nanostructures (GNS) is described. We show that fern leaf fractal-like GNS deposited on ITO electrodes are conducive for neural cell attachment and viability while reducing the interfacial impedance more than two orders of magnitude at low frequencies (100-1000 Hz) versus bare ITO. GNS MEAs, with low interfacial impedance, allowed the detection of extracellular action potentials with excellent signal-to-noise ratios (SNR, 20.26 ± 2.14). Additionally, the modified electrodes demonstrated electrochemical and mechanical stability over 29 d in vitro.

We report the characterization of photo-crosslinked polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) thin film, metal–insulator–metal capacitors fabricated using standard semiconductor processing techniques. We characterize the capacitors using in-situ vibrational spectroscopy during thermally-assisted poling and correlate the Fourier transform infrared spectroscopy (FTIR) results with X-ray diffraction (XRD) results. FTIR analysis of the neat PVDF-HFP showed α → β transformations during poling at room temperature and at 55 °C. α → β transformations were observed for the crosslinked polymer only during poling at 55 °C. XRD data revealed that photo-crosslinking caused the polymer to partially crystallize into the β -phase. The similar behavior of the neat and crosslinked samples at 55 °C suggests that a higher activation energy was needed for α → β transformations in crosslinked PVDF-HFP during poling. Electrical measurements showed that photo-crosslinking had no significant effect on the dielectric constant and dielectric loss of PVDF-HFP. However, the dielectric strength and maximum energy density of the crosslinked polymer were severely reduced.

By introducing a neat Pt(II)-based phosphor with a remarkably short decay lifetime, a simplifi ed doping-free phosphorescent organic light-emitting diode (OLED) with a forward viewing external quantum effi ciency (EQE) and power effi ciency of 20.3 ± 0.5% and 63.0 ± 0.4 lm W − 1 , respectively, is demonstrated. A quantitative analysis of how triplet-triplet annihilation (TTA) and tripletpolaron annihilation (TPA) affect the device EQE roll-off at high current densities is performed. The contributions from loss of charge balance associated with charge leakage and fi eld-induced exciton dissociation are found negligible. The rate constants k TTA and k TPA are determined by time-resolved photoluminescence experiments of a thin fi lm and an electrically-driven unipolar device, respectively. Using the parameters extracted experimentally, the EQE is modeled versus electric current characteristics of the OLEDs by taking both TTA and TPA into account. Based on this model, the impacts of the emitter lifetime, quenching rate constants, and exciton formation zone upon device effi ciency are analyzed. It is found that the short lifetime of the neat emitter is key for the reduction of triplet quenching.

Both operational lifetime and shelf-life of copper phthalocyanine (CuPc) based high frequency Schottky diodes have been studied in this work. Thin films of amorphous Si ( a -Si) and polychloro-(para-xylylene) (parylene C) are deposited as a barrier layer using low temperature chemical vapor deposition to improve the lifetime of the CuPc Schottky diodes. The CuPc Schottky diodes encapsulated with the barrier layer exhibit at least 6 × longer operational lifetime under both DC and AC voltage stress. Encapsulation does not significantly improve the shelf-life of the organic Schottky diodes.

In this work, the impact of film thickness in thermally evaporated pentacene thin films and metal electrodes is studied. In particular, we report electrical performance and stability of un-encapsulated organic Schottky diodes. The chemical composition, surface morphology and ambient stability of the resulting films were also studied. The electrical measurements were carried out in vertical Schottky diodes and its performance and stability was evaluated as function of shelf life time. Oxygen was detected at the pentacene surface. This oxygen is the main cause of the diode degradation and attributed to diffusion of oxygen into the bulk of the pentacene films. Thicker pentacene films resulted in more stable for Schottky diodes.

The structural, optical and dielectric characteristics of PMMA–TMSPM–SiO2 hybrid thin films, synthesized by sol–gel, were studied as a function of the molar concentration of the coupling agent (TMSPM) in the hybrid precursor solution. It was possible to obtain very homogenous films, with improved thermal stability and variable organic and inorganic composition. The hybrid films showed high uniformity, excellent optical transparency and tunable refractive index from 1.447 to 1.490 at 633 nm depending on the PMMA fraction in the films. The formation of both organic and inorganic components and their interaction in the hybrid material were confirmed by the analysis of the ATR–FTIR spectra, suggesting changes in the film structure caused by the variations of the TMSPM concentration. The dielectric constant of the hybrid films, determined from capacitance–voltage (C–V) measurements performed in metal–insulator–metal (MIM) configuration, had unexpectedly high values between 5 and 14, increasing with decreasing TMSPM molar ratio. Such high dielectric constant values were attributed to highly polarizable OH and C C groups in the hybrid films, OH being part of the residual precursor solvents and C C the result of incomplete conversion of precursor monomer (MMA) into polymer (PMMA), as shown by FTIR measurements. Furthermore, the dielectric constant of the hybrid films was modeled according to an effective media approximation model, taking into account the constituting organic and inorganic phases, residual O H and C C groups.

We have demonstrated a low temperature process for a ferroelectric non-volatile random access memory cell based on a one-transistor–one-capacitor (1T1C) structure for application in flexible electronics. The n-channel thin film transistors (TFTs) and ferroelectric capacitors (FeCaps) are fabricated using cadmium sulfide (CdS) as the semiconductor and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer as the ferroelectric material, respectively. The maximum processing temperature for the TFTs is 100 °C and 120 °C for the FeCaps. The TFT shows excellent access control of the FeCap in the 1T1C memory cell, and the stored polarization signals are undisturbed when the TFT is off. The fabricated 1T1C memory cell was also evaluated in a FRAM circuit. The memory window on the bit line was demonstrated as 2.3 V, based on the 1T1C memory cell with a TFT having dimensions of 80 μm/5 μm (W/L) and a FeCap with an area of 0.2 × 10−3 cm2 using a bit line capacitor of 1 nF pre-charged at 17.2 V. The 1T1C memory cell is fabricated using photolithographic processes, allowing the integration with other circuit components for flexible electronics systems.

Zinc Oxide (ZnO) Thin-Film Transistors (TFTs) using Aluminum (Al) and Aluminum-doped zinc Oxide (AZO) as Source-Drain (S-D) contacts are reported. The fabrication process was carried out using five photolithography steps with a maximum processing temperature of 100 °C, which makes the process compatible with flexible/transparent applications. The AZO and ZnO films were deposited using Pulsed Laser Deposition (PLD). Aluminum was deposited using ebeam. The devices showed mobilities >10 cm2/V-s, threshold voltage in the range of 7 V and On/Off current ratios >105. The resistance analysis showed that AZO is a better contact with lower contact resistance as identified in the TFTs. The AZO and ZnO stacks characterized by UV-V shows an optical transmission >80 %.

We report device and material considerations for the fabrication of high-mobility thin-film transistors (TFTs) compatible with large-area and inexpensive processes. In particular, this paper reports photolithographically defined n-type TFTs (n-TFTs) based on cadmium sulfide (CdS) films deposited using solution-based techniques. The integration process consists of four mask levels with a maximum processing temperature of 100°C. The TFT performance was analyzed in terms of the CdS semiconductor thickness and as a function of postdeposition annealing in a reducing ambient. The Ion/Ioff ratios are ~107 with field-effect mobilities of ~5.3 and ~4.7 cm2/V · s for Al and Au source-drain contacts, respectively, using 70 nm of CdS. Transmission electron microscopy and electron energy loss spectroscopy were used to analyze the CdS-metal interfaces.

Fabrication and characterization of integrated hybrid complementary metal oxide semiconductor devices (CMOS) using 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PC) and cadmium sulfide (CdS) as the active layers deposited using solution based processes are demonstrated. The n- and p-type thin film transistors (TFTs), inverters, and NAND gate devices were fabricated using photolithography-based techniques. The hybrid CMOS technology demonstrated is compatible with large-area and mechanically flexible substrates given the low temperature processing ( 2 /V s, respectively. The inverters exhibited a DC gain of ≈52 V/V with full rail-to-rail switching. The NAND logic gates switch rail-to-rail with a transition point of V DD /2.

Complete stone removal is important in upper tract stone surgery. Unfortunately, even with the latest technologic advances, current methods only achieve 50% to 80% complete clearance of upper tract stones at the time of primary treatment. Our group has explored the novel use of peptide-coated iron oxide superparamagnetic microparticles that bind to calcium stones, allowing for extraction of these stones with magnetic tools. We present analytic and numeric models that characterize stone attraction performance for feasible magnetic tool sizes and stone magnetization levels.Magnetostatics equations are applied to a simplified, one-dimensional scenario of a spherical target coated with a variable amount of superparamagnetic particles, placed under the influence of a magnetic field aimed at vertical attraction (capture) of the target. Equations are parameterized in terms of (a) target size, ranging from 0.5 mm to 3 mm to represent stone sizes of interest, (b) effective magnetization per surface area delivered by the particle binding chemistry, and (c) distance to the field source.Target capture is predicted to be effective in the low, single-digit millimeter distance range, favoring smaller stones and then up to a practical upper limit of 3 mm diameter. Higher iron loading chemistries have a direct improvement in magnetic force and therefore increase the viability of the technique, albeit along an asymptotic trendline.We are able to characterize the potential for kidney stone capture via magnetic attraction. Computer-developed models show good correlation with experimental results using actual magnetized stone samples. Future research efforts can use the proposed techniques to estimate the performance impact of advanced magnetic tools and surface chemistries.

There is an interest in higher-ZT thermoelectric materials for high-watt-density cooling of electronics. Reducing thermal conductivity through increased phonon scattering in nanomaterials has been shown to be effective and is being investigated by many groups. Solution-based synthesis is a method for making thermoelectric nanomaterials that can provide particle sizes

In this paper we demonstrate p-type thin film transistors fabricated with lead sulfide (PbS) as semiconductor deposited by chemical bath deposition methods. Crystallinity and morphology of the resulting PbS films were characterized using X-ray diffraction, atomic force microscopy and scanning electron microscopy. Devices were fabricated using photolithographic processes in a bottom gate configuration with Au as source and drain top contacts. Field effect mobility for as-fabricated devices was ~ 0.09 cm2 V− 1 s− 1 whereas the mobility for devices annealed at 150 °C/h in forming gas increased up to ~ 0.14 cm2 V− 1 s− 1. Besides the thermal annealing, the entire fabrications process was maintained below 100 °C. The electrical performance of the PbS-thin film transistors was studied before and after the 150 °C anneal as well as a function of the PbS active layer thicknesses.

We prepare ZnO:poly(3-hexylthiophene) (P3HT) thin-film solar cells and ZnO nanowire:P3HT nanostructured solar cells and evaluate the effect of adding an interfacial layer between the ZnO and P3HT as a function of the nanowire height. We evaluate several different interlayers of CdS deposited, using two different chemical bath deposition (CBD) recipes. The height of the nanowire array is varied from a bilayer device with no nanowires up to arrays with a height of 2 μm. We find that achieving a conformal coating of the ZnO with the interfacial layer is critical to improve device performance and that CBD can be used to grow conformal films on nonuniform surfaces.

Alternating layers of TiO 2 nanosheets and poly(ethylenimine) were sequentially dip coated onto a polyethylene naphthalate substrate (PEN) using layer-by-layer assembly. UV–vis spectroscopy shows a linear growth of the PEI/nanosheets bilayer on the PEN substrate. The cross-section microstructure of the LBL film was studied using scanning electron microscopy (SEM). Helium permeability measurement showed that the titania nanosheet/PEI bilayers reduced the permeation rate of He through the coated PEN film.

Planar microelectrode arrays (MEAs) permit the long-term, non-invasive monitoring of electrically active cells. Compared to disposable plastic chambers and cultured dishes used for in vitro tests, MEAs are typically reused in experiments since they are expensive. Here, we report the design and demonstration of a low-cost novel MEA using conventional liquid crystal display manufacturing techniques. The resulting MEA is flexible, conducive for neuronal culture, and capable of monitoring extracellular potentials at a signal-to-noise ratio comparable to standard commercially available MEAs. The design layout is consistent with results from finite-element modeling. Electrochemical impedance and input referred noise have been measured for the fabricated MEA. Finally, it was demonstrated that spike activity of the cultured cortical neurons on the MEA is sensitive to pharmacological blocker tetrodotoxin (TTX).

Lead zirconate titanate, Pb(Zr 0.53 ,Ti 0.47 )O 3 or PZT, thin films and integrated cantilevers have been fabricated for energy harvesting applications. The PZT films were deposited on PECVD SiO 2 /Si substrates with a sol–gel derived ZrO 2 buffer layer. It is found that lead content in the starting solution and ramp rate during film crystallization are critical to achieving large-grained films on the ZrO 2 surface. The electrical properties of the PZT films were measured using metal–ferroelectric–metal and inter-digital electrode structures, and revealed substantial improvement in film properties by controlling the process conditions. Functional cantilevers are demonstrated using the optimized films with output of 1.4 V peak-to-peak at 1 kHz and 2.5 g.

The electrical fatigue characteristics of 100 nm thick, solution processed poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer thin film Metal-Ferroelectric-Metal (MFM) capacitors have been studied. After one million stress cycles at an electric field of 1.4 MV/cm and 500 Hz switching frequency, 87% of the initial switching polarization is maintained, with the non-switching polarization remaining low. The kinetics of the switching polarization were studied before and after electrical stress. Fatigue increases the required activation field for switching polarization and suppresses switchable polarization. The activation field increases after electrical stress and higher activation fields were required for higher electric field stressing. The reduction in switchable polarization is approximately 10% of the initial switching polarization for all electric fields and frequencies studied. We demonstrated that under operating conditions compatible with flexible electronic applications, the optimized ferroelectric thin film capacitor reported shows stable switching polarization and acceptable fatigue after electrical stress.

We have developed novel iron-based microparticles (Fe-MP) that bind to calcium oxalate stone fragments, rendering them paramagnetic. Previously, we demonstrated enhanced efficiency of stone extraction in an inanimate model using magnetic instrumentation. Before in vivo stone extraction studies, we sought to further characterize Fe-MP with regard to cellular toxicity and to assess the influence of biologic fluids on binding performance.Monolayers of murine fibroblasts, human urothelium, and human transitional-cell carcinoma cells were exposed to 1 mg/mL of Fe-MP or saline via an agarose overlay. Cellular viability was assessed using neutral red staining and densitometry. Biologic functionality: Human calcium oxalate stone fragments were incubated with a solution of 1 mg/mL of Fe-MP containing varying concentrations of urine (10%-50%) or blood (0.5%-2%) for 10 minutes. Fragments were then extracted using an 8F magnetic tool. Assays of 10 stone fragments categorized as small (3-3.9 mg) or large (6-6.9 mg) were run in quadruplicate at each concentration.No toxicity was seen in any of the three cell lines after 48 hours of particle exposure, except in urothelial cells at the lowest cell concentration. Stone extraction success was 100% for all stones, regardless of concentration of urine or blood, and extractions were completed in less than 10 minutes.Preliminary toxicity testing revealed minimal to no cellular toxicity that was attributable to Fe-MP. The microparticles function well in the presence of clinically relevant concentrations of urine and blood that may be present during endoscopic stone surgery. Further toxicity and stone extraction testing in animal models is necessary.