Solution Deposition Technique Research Articles

PZT based dual energy harvester using chemical solution deposition technique

The present finding reports the state-of-art thin film based dual energy harvester which can harvest both mechanical as well as magnetic energies. Dual energy harvester is realised with the help of Lead Zirconium Titanate (PZT) thin film and nickel (Ni) foil. Ferroelectric PZT has been grown with the help of chemical solution deposition technique under optimised conditions on Nickel cantilevers. The effect of damping mass on the resonating frequency of the PZT-60/Ni dual cantilever has been studied. The maximum power and voltage generated by dual energy harvester at the matching load impedance of 100 kΩ under resonance condition were about 117 × 102 mW/m3 and 52 mV respectively corresponding to an applied acceleration of 1.0 g. A change of about 0.5 mV/Oe voltage was achieved for PZT-60/Ni cantilever in the presence of magnetic field. The dual energy harvester prepared with the help of chemical solution technique is found to have profound response and hence enables the realization of self powered electronic devices by scavenging an ambient magnetic and mechanical energies for various wireless electronic applications ranging from medical implant to health monitoring areas.

Investigating mechanism of photo refractivity in Mg substituted ZnO thin films using pump and probe technique

In the current investigation magnesium (Mg) has been incorporated in the ZnO matrix to induce photo refractivity thereby adding an extra dimension to its already present multi-functionality. Undoped and MgxZn1-xO (x = 0.25, 0.30, 0.35, 0.40, 0.45) thin films have been grown using Chemical Solution Deposition (CSD) technique. Obtained X-Ray Diffraction (XRD) spectra exhibits a slight shift in the peak value along (002) plane whereas UV–visible spectra indicates corresponding widening of ZnO band gap values (3.24–3.64 eV) with increase in Mg content. Mg substituted ZnO films were then investigated for their ferroelectric properties using a P-E hysteresis loop tracer. It was noted that ZnO film with 35 % Mg content (x = 0.35) exhibited the high values for saturation (Ps = 1.8 μC/cm2) and remnant (Pr = 0.7 μC/cm2) polarization. Hence the ZnO with same Mg concentration was investigated for nonlinear optical properties (two wave mixing phenomenon) using pump and probe technique. In order to enhance the beam amplification gain and impart stability Au micro-dots were thermally evaporated onto MgxZn1-xO (x = 0.35) films. The maximum beam amplification gain was noted to shoot up to 2.7 post patterning of MgxZn1-xO (x = 0.35) film surface by Au micro-dots.

Plasmonic electro-optic modulators on lead zirconate titanate platform

Abstract The advancement in material platforms exhibiting strong and robust electro-optic effects is crucial for further progress in developing highly efficient and miniaturized optoelectronic components with low power consumption for modern optical communication systems. In this work, we investigate thin-film lead zirconate titanate (PZT) substrates grown by a chemical solution deposition technique as a potential platform for on-chip plasmonic electro-optic modulators. A high modulation depth (>40 %) is achieved with 15 μm-long electro-optic directional coupler modulators. An unusual cutoff in the modulation frequency response at ∼200 kHz is observed and further studied with respect to possible reorientation effects. Second-harmonic generation signals are found influenced by the externally applied electric field, indicating that the domain reorientation effect can be responsible for the unusual frequency response observed.

Remote epitaxy-based atmospherically stable hybrid graphene template for fast and versatile transfer of complex ferroelectric oxides onto Si

Heterogenous integration of complex epitaxial oxides onto Si and other target substrates is recently gaining traction. One of the popular methods involves growing a water-soluble and highly reactive sacrificial buffer layer, such as Sr3Al2O6 (SAO), at the interface and a functional oxide on top of this. To improve the versatility of layer transfer techniques, it is desired to utilize stable (less reactive) sacrificial layers without compromising on the transfer rates. In this study, we utilized a combination of chemical vapor deposited (CVD) graphene as a 2D material at the interface and pulsed laser deposited (PLD) water-soluble SrVO3 (SVO) as a sacrificial buffer layer. We then exploit the well-known enhancement of liquid diffusivities by monolayer graphene to enhance the dissolution rate of SVO over ten times without compromising its atmospheric stability. We demonstrate the versatility of our hybrid- graphene-SVO- template by growing ferroelectric BaTiO3 (BTO) via PLD and Pb(Zr, Ti)O3 (PZT) via Chemical Solution Deposition (CSD) technique and transferring them onto the target substrates and establishing their ferroelectric properties. Our hybrid templates allow for the realization of the potential of complex oxides in a plethora of device applications for MEMS, electro-optics, and flexible electronics.

Enhanced piezoelectric properties in europium-doped lead lanthanum zirconate titanate thin films

This paper investigates the effect of europium (Eu3+) doping on the crystal structure, dielectric and piezoelectric properties of lead lanthanum zirconate titanate (PLZT) thin film. For the present study, Pb0·92(La1-yEuy)0·08(Zr0·52Ti0·48)O3 (PLEZT) compositions with various Eu concentrations (y = 0.0, 0.3, 0.5 and 0.7) were prepared on Si/SiO2/Ti/Pt substrates by chemical solution deposition technique. The X-ray diffraction and Raman spectroscopy studies revealed the structural distortions in PLZT films with Eu doping. The piezoelectric charge coefficient showed significant enhancement with Eu doping for y = 0.5 composition, with good room temperature frequency stability. This improvement in the piezoelectric characteristics of PLEZT films is the result of stronger intrinsic contributions brought in by bigger c/a ratios and higher extrinsic contributions from non-180° domain wall motions.

Thin Film Transistors Incorporating Ultrapure Semiconducting Single-Walled Carbon Nanotubes and Green Dielectrics

Printed electronics is a burgeoning field that has received intense research interest and is beginning to experience commercial successes. Single-walled carbon nanotubes (SWNTs) are a unique and promising building block for incorporation into next generation superfast electronic devices. SWNTs have very high carrier mobilites, with band gaps compatible for integration into logic circuits. Their excellent mechanical flexibility allows for potential incorporation into flexible printed electronics, enabling fully-printed transistors and circuits with performances that support low cost, large area fabrication. Progress in incorporating SWNTs into commercial devices has been hindered by the presence of metallic SWNTs, which are produced alongside semiconducting SWNTs during synthesis, and negatively impact device performance. Fabrication of ambipolar SWNT organic thin film transistors (OTFTs) with high carrier mobilities and high on/off ratios remains particularly challenging; many examples in the literature required high temperature, expensive and energy-demanding processes.Since the initial discovery of conjugated polymer-assisted dispersion and purification of SWNTs in 2008, several polymer families have been successfully shown to selectively disperse semiconducting SWNTs. However, only a relatively small number of these supramolecular complexes have been incorporated into OTFTs. We used a novel conjugated polymer to exclusively disperse semiconducting SWNTs. The dispersal procedure requires a simple sonication and centrifugation, during which the metallic SWNTs sediment out. Solution purity was evaluated using UVVis- NIR and Raman spectroscopies. The resulting dispersions are amenable to solution processing techniques such drop casting and spin coating, allowing for the potential for large area device fabrication at room temperature. Ambipolar OTFTs were fabricated under ambient conditions using this solution and tested in both air and under inert atmosphere. The presence of excess conjugated polymer, solution deposition techniques, SWNT density, surface treatment, and post-fabrication treatment were all investigated to determine which parameters facilitated the production of OTFTs with high mobilities (>20 cm2V-1s-1), high on/off ratios (10^6-10^8), negligeble hysteresis, controlled threshold voltages, and high bias stability.[1] Protocols for sorting and dispersing ultrapure sc-SWNTs with conjugated polymers for thin-film transistor (TFT) applications have been well refined. Conventional wisdom dictates that removal of excess unbound polymer through filtration or centrifugation is necessary to produce high- erformance TFTs. However, this is time-consuming, wasteful, and resource-intensive. We challenge this paradigm and demonstrate that excess unbound polymer during semiconductor film fabrication is not necessarily detrimental to device performance.[2] With focus on further improving device performance, we look to green, compostable dielectrics to pair with SWCNTs. We report a tri-layer dielectric using poly (lactic acid) (PLA), poly(vinyl alcohol)/cellulose nanocrystals (PVAc) and toluene diisocyanate terminated poly(caprolactone) (TPCL) which we integrated into SWCNT based TFTs in a top gate bottom contact architecture. The PVA provides a high dielectric constant due to the hydroxy groups, the cellulose is used to optimize the viscosity, the TPCL layer provides a robust hydrophobic surface[3], and the PLA eliminates the interfacial charge traps present in the PVAc. This leads to a decrease in leakage currents and reduced the polarity at the dielectric/semiconductor interface. The TFTs fabricated using tri-layer dielectrics led to air stable and balanced hole and electron mobilities which was not observed for the PVAc/TPCL bilayer systems with supressed hole mobility. These TFTs were then used to study the impact of electrochemical doping on the performance of sc-SWCNT TFTs when switching from n-type, where an electrical double layer is formed, to p-type, where the TFSI anions are free to interact with the sc-SWCNTs.[4]The following presentation will focus on the engineering of sc-SWNTs based electronic devices. The choice of conjugated wrapping polymer, dielectric and processing conditions on film formation and the TFT device performance.

Sol-gel synthesis and Opto-electrical properties study of double perovskite oxide Dy2NiMnO6 thin film

Thin film of double perovskite oxide Dy2NiMnO6 (DNMO) has been synthesised by the simple and cost-effective chemical solution deposition technique. The room temperature X-ray diffraction pattern and Raman spectroscopy confirm the monoclinic (space group - P21/n) crystal structure of polycrystalline DNMO thin film. The optical and electrical properties of DNMO thin film are investigated to study the detailed photo physical properties of DNMO thin film. The direct band gap and temperature dependant impedance spectroscopy confirm its semiconductor behaviour. Impedance spectroscopy also shows two types of dielectric relaxation behaviour and the nature of conductivity reveals the electron hopping conduction mechanism. Moreover, the chemical solution deposited DNMO film shows promising photo response under white light.

Processing and Weathering of Sol-Gel Clearcoats for Coil-Coated Steel

Clearcoats provide long-term aesthetics and protection for underlying coating systems, increasing product lifetimes. However, organic clearcoats are predominantly produced using fossil-fuel feedstocks. In search of a sustainable alternative, an experimental investigation was conducted on the development of glass-like clearcoats produced using the sol-gel process. The processing of sol-gel clearcoats over a pigmented polyurethane coating was studied by modifying the sol-gel solution pH, ageing, curing, precursor chemistry and deposition techniques. Under optimal formulation and processing conditions, defect-free sol-gel clearcoats were produced that have the potential to be scaled up to a coil-coating line using existing technologies. Mechanical testing demonstrated the coatings had excellent adhesion, hardness, and flexibility. Furthermore, accelerated laboratory weathering tests revealed the sol-gel coatings had superior degradation resistance compared to the organic coatings tested, resulting in negligible colour changes and higher gloss retention after 4000 h of exposure. The durability and environmental benefits of sol-gel clearcoats highlight their potential as a replacement for traditional organic clearcoats in a variety of applications.

Tunable resistive nature of LaMnO3 / Nd0.7Sr0.3MnO3 interfaces: Role of swift heavy ion irradiation

In the present communication, high crystalline quality LaMnO3/Nd0.7Sr0.3MnO3/SrTiO3 (LMO/NSMO/STO) structures were fabricated using low cost chemical solution deposition (CSD) technique to perform swift heavy ion (SHI) irradiation using 100 MeV O+7 ions. X–ray diffraction (XRD) θ–2θ, XRD φ–scan and XRD ω–scan results show a single phase nature having finite and ion fluence influenced strain state, four–fold lattice symmetry with epitaxial growth and an effective influence of ion fluence on the crystalline granular structure of LMO/NSMO/STO structure. Atomic force microscopy (AFM) images suggest an effect of ion fluence on the surface morphology through the creation of defects and local annealing effect. Zero field cooled (ZFC) protocol based LMO/NSMO interface resistivity suggests that transport nature of the LMO/NSMO interface of all studied LMO/NSMO/STO structures is strongly governed by lattice strain between LMO//NSMO layers and STO substrate, strain across LMO and NSMO manganite layers, crystalline granular structure, grain size, grain boundary density and grain boundary nature of the LMO and NSMO manganite thin layers. ZFC protocol followed by field cooled cooling (FCC) and field cooled warming (FCW) protocols for the realization of LMO/NSMO interface resistivity behaviors have been understood on the bases of freezing and trapping of tiny high temperature high resistive insulating clusters within the coexisting low temperature low resistive metallic phase fraction. Observed LMO/NSMO interface resistivity behaviors have been understood using the percolation model fits to the recorded experimental LMO/NSMO interface resistivity data in addition to irradiation influences. Obtained fitting parameters have been discussed in detail based on their variations with different employed resistivity measurement protocols for all pristine and irradiated LMO/NSMO/STO structures.

Synthesis of PEDOT: PSS thin film doped with silver nanoparticles via green approach and study their refractive indices and dispersive parameters using Wemple–DiDomenico (WDD) single oscillator model

Silver nanoparticles (AgNPs) synthesised via green synthesis using clove extract were incorporated into PEDOT:PSS polymers using the chemical solution deposition technique (CSD), and the effect of surface plasmon resonance in the nanocomposites was investigated. To assess the effect of Silver nanoparticles (AgNPs) (and surface plasmon resonance) on the polymer, TEM, UV–Visible spectroscopy, FTIR, Ellipsometry, and Photoluminescence are used. The surface plasmon peak of the curves in UV–Vis spectroscopy study of these films has shifted towards the infrared region, which may be useful in increasing the efficiency of optical devices. The optical band gap calculated using UV–Vis results reduced from 1.77eV for pure PEDOT: PSS to 1.53eV for the nanocomposite. Ellipsometry data is used to calculate Ψ, Δ values and thickness of films. The Wemple-DiDomenico (WDD) single oscillator model was used to analyse and estimate the dispersion parameters of these films. Refractive indices the films were calculated in the range 1.256–1.643 using the Ellipsometry data.

Epitaxial bilayer La0.7Sr0.3MnO3/Ba0.7Sr0.3TiO3 thin films obtained by polymer assisted deposition

In this work bilayer structures, composed of ferromagnetic manganite and ferroelectric titanate layers, were obtained by solution deposition technique. The first step in preparation of the bilayer thin films was deposition of manganite (LaMnO3 or La0.7Sr0.3MnO3) layer by water-based polymer assisted deposition (PAD). Polycrystalline structures were obtained when manganite films were deposited by spin coating on commercial Pt/TiO2/SiO2/Si type substrate, whereas epitaxial films were grown on a single crystal SrTiO3 with (001) orientation substrate. The second ferroelectric titanate (BaTiO3 or Ba0.7Sr0.3TiO3) layer was deposited by spin coating using sol-gel method. The obtained bilayer structures have thickness below 100 nm, and epitaxial growth of the Ba0.7Sr0.3TiO3 film on the La0.7Sr0.3MnO3 surface was obtained, due to the similar lattice parameters between these two crystal structures.

THE SUBTRACTIVE PROCESS OF FORMING A METALLIZATION SYSTEM.

The subtractive process of forming a metallization system for integrated circuits has been studied. Structures with aluminum and copper conductors with different pitches were used as models. The gaps between the conductors were filled using the chemical solution deposition technique. The formed organosilicate layers provided complete or partial planarization of the relief. Electrical measurements indicated a decrease in capacitance and leakage currents in structures with nanoporous dielectric layers.

Materials Design Strategies for Solvent-Resistant Organic Electronics

Design of organic π-conjugated semiconducting materials is an exciting avenue of research that has already found promising applications in a wide variety of fields, ranging from stretchable electronics to bioimaging and theranostics. With favorable optoelectronic and thermomechanical properties, these materials and related devices can provide a complementary alternative to commercial silicon-based electronics. One of the most important features of organic semiconductors is their ability to be solution processed, allowing access to a wide variety of printing and solution deposition techniques inaccessible to silicon. However, the solution processability of these materials also poses challenges for the development of multilayer electronics due to potential problems such as swelling, film deformation and interfacial mixing that can occur upon successive solution deposition. Use of orthogonal (noncompatible) solvents and solvent-free deposition methods have been extensively investigated as solutions to this challenge, although the applicability of these approaches is limited by the chemical properties of the materials used. Another approach to address this problem is to focus on the materials rather than deposition methods. Through rational design, functional groups can be used to create triggered solvent resistance through covalent or dynamic intermolecular bonds. Design strategies include the incorporation of photo- and thermally cleavable functional groups in the materials, or the use of chemical additives/reagents to significantly alter the solubility of π-conjugated materials and afford solvent-resistant thin films. This spotlight article presents recent progress toward solvent-resistant organic materials with an emphasis on their use in electronic applications. Recent and key developments will be discussed from a personal perspective, providing an overview of the different approaches used to achieve solvent-resistant semiconducting materials toward the fabrication of advanced, multilayer organic electronics.

Chemical and Microstructural Nanoscale Homogeneity in Superconducting YBa2Cu3O7-x Films Derived from Metal-Propionate Fluorine-free Solutions.

Research involved in developing alternative energy sources has become a necessity to face global warming. In this context, superconductivity is an appealing solution to enhance clean electrical energy provided that lower production costs can be attained. By implementation of chemical solution deposition techniques and high-throughput growth methods, low-cost nanostructured epitaxial cuprate superconductors are timely candidates. Here, we present a versatile and tunable solution method suitable for the preparation of high-performance epitaxial cuprate superconducting films. Disregarding the renowned trifluoroacetate route, we center our focus on the transient liquid-assisted growth (TLAG) that meets the requirement of being a greener chemical process together with ultrafast growth rates beyond 100 nm/s. We developed a facile, fast, and cost-effective method, starting from the synthesis of metal-propionate powders of Y, Ba, and Cu of high purity and high yields, being the precursors of the fluorine-free solutions, which enable the chemical and microstructural nanoscale homogeneity of YBa2Cu3O7-x (YBCO) precursor films. These solutions present endured stability and enable precise tunability of the composition, concentration, porosity, and film thickness. Homogeneous precursor films up to thicknesses of 2.7 μm through eight layer multidepositions are demonstrated, thus establishing the correct basis for epitaxial growth using the fast kinetics of the TLAG process. YBCO films of 500 nm thickness with a critical current density of 2.6 MA/cm2 at 77 K were obtained, showing the correlation of precursor film homogeneity to the final YBCO physical properties.

Dielectric and ferroelectric properties of multilayer BaTiO3/NiFe2O4 thin films prepared by solution deposition technique

In this work different lead-free multilayered structures, composed of perovskite BaTiO3 and spinel NiFe2O4 thin layers, were obtained by solution deposition method. Structural characterization of the sintered thin films confirmed the well-defined layered structure with overall thickness from 160 to 600 nm, crystalline nature of perovskite BaTiO3 and spinel NiFe2O4 phases without secondary phases (after sintering below 900 °C) and grains on nanometer scale. Dielectric properties of the multiferroic multilayer BaTiO3/NiFe2O4 thin films were analyzed in temperature and frequency range from 30 °C to 200 °C and 100 Hz to 1 MHz, respectively. In comparison to the pure BaTiO3 films, the introduction of ferrite layer reduces dielectric response and increases low frequency permittivity dispersion of the multilayer thin films. The multilayer samples have shown relatively low dielectric loss with stronger contribution of conductivity at higher temperatures, and characteristic broad peak representing “relaxation” of the interface charge accumulation.

A flexible pressure sensor based on PEDOT coated polyester nonwoven fabric for low-pressure range

Three most common methods for preparing PEDOT (poly(3,4-ethylenedioxythiophene)) are studied, including vapor phase polymerization (VPP), in-situ dipping (ISD) and solution deposition (SD) techniques. The PEDOT coated nonwoven fabric (PEDOT@NWF) composites were successfully fabricated via these three processes and have been proven to be conductive and equipped with piezoresistive properties. For each preparation method, factors that may affect product properties, such as concentrations of reagents, reaction temperature, reaction time, etc were explored to summarize the optimal parameters. The PEDOT@NWF composites prepared via different fabrication techniques were analyzed and compared through a series of tests and characterizations. The sensing performance of as-prepared pressure sensors are also been studied. The experimental results demonstrate that PEDOT@NWF prepared by VPP method (PEDOT@NWF-VPP) has the fastest response time (80 ms) and recovery time (40 ms), the composite prepared by ISD method (PEDOT@NWF-ISD) has the highest sensitivity for the pressure range less than 5 kPa (21.162 kPa−1) and long-term cycle stability (over 5000 cycles). Sensor utilized PEDOT@NWF-ISD as the piezoresistive layer was assembled and used to detect small pressure such as voice vibrations and air flow, implying that this designed pressure sensor has promising potential in the application of wearable electronic devices and healthcare monitors.

Effect of treatment condition on perovskite film for perovskite solar cell application

In this study, the Perovskite material CH3NH3PbI3 was prepared using two-step sequential solution deposition technique. The treatment condition for Perovskite film including dipping duration, reaction temperature and annealing temperature was studied. Crystal structure, grain size, and purity of the prepared material were examined using XRD and SEM methods. The results indicate that controlling treatment condition has a significant effect on the crystallinity and purity of Perovskite film. Under suitable condition, the obtained Perovskite material has a tetragonal structure and grain size ranges from 200 to 400 nm. The Perovskite film was then applied as a light-harvesting material in Perovskite solar cell. The device exhibits a power conversion efficiency of 5.18% with JSC of 13.6 mA cm-2, VOC of 0.83 V, and fill factor of 45.9%.

Controlling the Morphology of PEDOT:PSS Blend Films with Pre-Deposition Solution Composition and Deposition Technique

Controlling the Morphology of PEDOT:PSS Blend Films with Pre-Deposition Solution Composition and Deposition Technique

Influence of morphology on photoanodic behaviour of WO3 films in chloride and sulphate electrolytes

Photoelectrochemical (PEC) synthesis is gaining an increasing interest amongst the advanced oxidation processes, which can convert solar energy to chemical energy in the form of value-added oxidants suitable for water treatment and disinfection. To ensure the efficient generation of desired product, careful engineering of semiconductor/electrolyte interface is required. In this study the effect of surface morphology on the competition between the photoanodic oxidation of water molecules and anions occurring on the surface of tungsten (VI) oxide electrodes in sulphate and chloride electrolytes is analysed. Four WO3 coatings composed of plate-like particles, similar in shape but of different sizes, were prepared using chemical solution deposition technique and methanol, ethanol, isopropanol or butanol as reductants. Crystalline structure, morphology, surface chemical composition and optical properties of the coatings were characterised applying X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and photoluminescence spectroscopy techniques. The photoelectrochemical performance of WO3 layers was studied using the methods of electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometry. Possible photoanodic processes are analysed on the basis of the proposed potential-assisted photochemical approach, which takes into consideration high oxidizing power of photogenerated holes in WO3 and formation of radicals as intermediates. Significant role of specific adsorption of chloride ions as well as intermediate products of their oxidation (Cl·, Cl2˙−) in lowering the photocurrent onset potential, trapping the photogenerated charge carriers as well as protecting WO3 surface from accumulation of hydroxo species is revealed. Influence of morphology on the competition between certain photoanodic reactions occurring at the semiconductor/electrolyte interface in the PEC systems investigated is explained considering the effects of steric hindrance as well as electrostatic interactions between adsorbing/reacting species at rough electrified interfaces.

Photophysical and Electro-Optical Properties of Copolymers Bearing Blue and Red Chromophores for Single-Layer White OLEDs.

In this study, novel copolymers consisting of blue and red chromophores are presented to induce emission tuning, enabling the definition of white light emission in a single polymeric layer. These aromatic polyether sulfones exhibit high molecular weights, excellent solubility and processability via solution deposition techniques. In addition, by carefully controlling the molar ratios of chromophores composition, the energy transfer mechanism, from blue to red chromophores, takes place enabling us to define properly the emission covering the entire range of the visible spectrum. The optical and photophysical properties of the monomers and copolymers were thoroughly investigated via NIR-Vis-far UV Spectroscopic Ellipsometry (SE), Absorbance and Photoluminescence (PL). These copolymers are used as an emissive layer and applied in solution-processed WOLED devices. The fabricated WOLED devices have been subsequently studied and characterized in terms of their electroluminescence properties. Finally, the WOLED devices possess high color stability and demonstrate CIE Coordinates (0.33, 0.38), which approach closely the pure white light CIE coordinates.