Charge transport and optical properties of MOCVD-derived highly transparent and conductive Mg- and Sn-doped In2O3 thin films

Mg- and Sn-doped In2O3 (MgIn(x)Sn(y)O(z), 6.0 < x < 16.0; 3.0 < y < 8.0) thin films were grown by low-pressure metal-organic chemical vapor deposition using the volatile metal-organic precursors tris(2,2,6,6-tetramethyl-3,5-heptanedionato)indium(III) [In(dpm)3], bis(2,4-pentanedionato)tin(II) [Sn(acac)2], and bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(N,N,N',N'-tetramethylethylenediamine)magnesium(II) [Mg(dpm)2(TMEDA)]. Films in this compositional range retain the cubic In2O3 bixbyite crystal structure. The highest conductivity is found to be approximately 1000 S/cm for an as-grown film with a nominal composition MgIn14.3Sn6.93O(z). Annealing of such films in a vacuum raises the conductivity to approximately 2000 S/cm. The optical transmission window of the present films is significantly wider than that of typical indium tin oxide (ITO) films from 300 to 3300 nm, and the transmittance is also greater than or comparable to that of commercial ITO films.     

氮掺杂二氧化钛-氧化镍双层薄膜的光电致色特性

以金属钛为靶材、O2/N2/Ar混合气氛为溅射气体,在导电玻璃(ITO)表面磁控溅射一层薄膜,再经300-500℃退火处理制备了氮掺杂TiO2薄膜.采用X射线衍射(XRD)、X光电子能谱(XPS)、扫描电子显微镜(SEM)和紫外-可见吸收光谱等对薄膜的微观结构、光学特性和光电化学性能等进行了研究.进而采用化学沉积的方法在TiO2-xNx薄膜表面沉积上一层多孔NiO薄膜,研究表明,制备的ITO/TiO2-xNx/NiO双层薄膜具有明显的光电致色特性,400℃退火处理的氮掺杂TiO2薄膜具有最高的光电流响应,经氙灯照射1h后,薄膜从无色变成棕色,500nm波长处光透过率从79.0%下降至12.6%.     

The effect of polyvinyl alcohol (PVA) on the optical,electrical and solid state properties of copper zinc tin sulfide (CZTS) deposited by sensitive spray pyrolysis (SSP)

Recently, the use of CZTS as the basis for other generation of low cost thin films solar cells has stimulated further researches. Its excellent p-type absorber nature, relatively high absorption coefficient and ideal energy band-gap of 1.5eV motivated these efforts. Additionally, CZTS consist of earth-abundant, cheap and non-toxic elements with very low manufacturing cost. Initially, copper indium gallium selenide (CIGS) solar cell device emerged but suffered limitations in further development because of rare indium and gallium in the device structure therefore, CZTS is recently preferred as an alternative to CIGS commercial solar cell absorber layer. In this work, solution mixture of CZTS and PVA was deposited on a substrate at temperature of 150 °C. Sensitive spray pyrolysis was used to grow the thin films where calculated amount of the precursor mixture was allowed to fall and be deposited on a heated substrate to form CZTS/PVA thin films. Subsequently, the thin film samples were annealed at a temperature of 200^oCfor 1 h to achieving pure crystalline thin film formation. SEM, XRD analysis, Optical, Solid State properties and Raman analysis were studied. The XRD analysis showed that the thin films fell into the pure kesterite structure of CZTS. Results show that produced thin films exhibited higher absorption coefficient and optical conductivity than pure CZTS, 10⁶ m^?1 and 10¹⁴(S^?1) against 10⁴cm^?1 and 10¹²(S^?1) respectively. The band-gap is between 1.53eV and 1.73eV. Using a PVA concentration of 0.05 M yielded highest absorbance and optical conductivity with lowest real dielectric constant and transmittance. These improved optical, electrical and solid state properties suitably qualify these thin films as absorber layer material for solar cell applications.     

Studies on nanocrystalline cadmium sulphide (CdS) thin films deposited by spray pyrolysis

Cadmium chalcogenides with appropriate band gap energy have been attracting a great deal of attention because of their potential applications in optoelectronic devices. CdS in the form of thin film is prepared at different substrate temperatures by a simple and inexpensive chemical spray pyrolysis technique. The as-deposited thin films have been characterized by XRD, SEM, EDAX and electrical resistivity measurement techniques. The XRD patterns show that the films are polycrystalline with hexagonal crystal structure irrespective of substrate temperature. SEM studies reveal that the grains are uniform with uneven spherically shaped, distributed over the entire surface of the substrates. Compositional analysis reveals that the material formed is stoichiometric at the optimized substrate temperature. The optical band gap energy is found to be 2.44 eV with direct allowed band-to-band transition for film deposited at 300°C. The electrical resistivity measurement shows that the films are semiconducting with a minimum resistivity for film deposited at 300°C. The thermoelectric power measurement shows that films exhibit n-type of conductivity.     

溶胶-凝胶方法制备ZnO:Al薄膜及其制备工艺条件研究

采用Sol-Gel工艺在玻璃基片上制备出C轴择优取向性、高可见光透过率以及高电导率的Al³⁺离子掺杂的ZnO透明导电薄膜ZnO:Al(ZAO薄膜).并研究了退火温度、Al掺杂量等对其光电性能的影响.结果表明,溶胶-凝胶法制备ZAO薄膜的最佳工艺条件为:溶胶浓度0.75 mol/L、掺杂量1.5 atm%,镀膜层数10层(厚度约为136 nm)、退火温度600℃.     

Organization and properties of a conjugated poly(heteroarylene methines) at the air-water interface and in the Langmuir-Blodgett films

A poly(heteroarylene methine) derivative, poly[(2,5-thiophenediyl) (p-n-methyl, n-octylaminobenzylidene) (2,5-thiophenequinodimethaneiyl)] (PTABQ), has been synthesized and spread at the air-water interface. The influences of three kinds of solutions on PTABQ monolayer behavior at the air-water interface have been investigated via the measurements of the pi-A isotherm and film stability. The results show that all three kinds of PTABQ solutions are apt to form the stable and transferable monolayer film organized with the plane of its pi-system nearly perpendicular to the air-water interface. Moreover, the monolayer-forming ability of PTABQ can be improved by introducing a water-soluble amphiphilie as an extractable spread-aiding component, which is further proved by the AFM images and FTIR spectra of the transferred films. UV-visible absorption spectra indicate that the well-ordered layer-by-layer structure is successfully controlled in the LB films. The optical bandgap of PTABQ is reduced for the ordered arrangement of its molecules in LB films. The intrinsic electrical conductivity of PTABQ LB films is 8.1 x 10(-8) S/cm and the conductivity of iodine-doped films is 5.7 x 10(-7) S/cm.     

Effects of annealing on the structural,electrical and optical properties of reactively evaporated thin fdlms of indium oxide

Thin films of indium oxide were prepared by thermal reactive evaporation of a mixture of indium oxide and metallic indium. This work is an experimental study of the modifications induced by an annealing treatment, on the structural, electrical and optical properties of indium oxide (In₂O₃). The results show important changes of different parameters determined after annealing. The films obtained after annealing at 350 °C for 3 hours under oxygen atmosphere have a good cristallinity. These films showed a transmittance of more than 80% in the visible region and a conductivity >10³ (Ω.cm)⁻¹.     

Volatile magnesium octahydrotriborate complexes as potential CVD precursors to MgB2. Synthesis and characterization of Mg(B3H8)2 and its etherates

The solid-state reaction of MgBr2 and NaB3H8 at 20 degrees C, followed by sublimation at 80 degrees C and 0.05 Torr, affords Mg(B3H8)2 as a white solid. Similar reactions with MgBr2(Et2O) and MgBr2(Me2O)1.5 afford the crystalline ether adducts Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2, respectively. In contrast, reactions of MgBr2 with NaB3H8, the presence of excess solvent result in the formation of nonvolatile, probably ionic, magnesium compounds of the type [MgLx][B3H8]2. The adducts Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2 are the first crystallographically characterized magnesium complexes of the B3H8- ligand; in both structures, the magnesium center adopts a distorted cis-octahedral geometry with two bidentate B3H8 groups and two Et2O ligands. Owing to their volatility, Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2 are potential precursors for the deposition of MgB2 thin films, although preliminary efforts to employ them as chemical vapor deposition sources produce boron-rich MgBx films instead, with x approximately 7. Finally, the synthesis and structure of Cp2Mg(thf) are described: this mono-thf adduct of Cp2Mg bears two eta5-Cp groups, unlike other Lewis base adducts of Cp2Mg, which contain one eta5-Cp group and one eta1- or eta2-Cp group.     

Influence of Electrical,Chemical and Morphological Properties of Inorganic/Organic Interface on Light Emitting Devices Performance

studies on the influence of chemical and physical treatments on the properties of indium–tin oxide (ITO) thin films are reported. The ITO films are utilized as transparent anodes of organic light-emitting diodes (OLEDs) incorporating poly(9,9-dihexyl-9H-fluorene-2,7-diyl) (PF6) as the hole transporter material and 8-hydroxyquinoline aluminum salt (Alq3) as emitter material. Chemical (HCl, piranha solutions), thermal (vacuum annealing), physical treatments (oxygen plasma, UV ozone) and combined treatments are studied. First, ITO layers with different treatments are characterized by using four point probe method, contact angle measurement, X-Ray diffraction (XRD), surface profilometer, scanning electron microscopy (SEM), UV-Vis-IR transmittance. Later, electrical and optical properties of OLEDs with treated ITO as anode are extensively investigated.     

Magnesium isotope separation by ion exchange using hydrous manganese(IV) oxide

The magnesium isotope effects were investigated by chemical ion exchange with a hydrous manganese(IV) oxide. The capacity of manganese(IV) oxide was 0.5 meq g(-1). The distribution coefficient of magnesium ions on the MnO(2) was determined by a batch method. The heavier isotopes of magnesium were enriched in the solution phase, while the lighter isotopes were enriched in the hydrous MnO(2) phase. The separation factor was determined according to the method of Glueckauf from the elution curve and isotopic assays. The separation factors of (24)Mg(2+)-(25)Mg(2+), (24)Mg(2+)-(26)Mg(2+), and (25)Mg(2+)-(26)Mg(2+) isotope pair fractionations were 1.011, 1.021, and 1.011, respectively.     

镁掺杂对In2O3电导和气敏性能的影响

用共沉淀法制备了Mg2+掺杂的In2O3纳米粉,研究了镁掺杂对In2O3电导和气敏性能的影响.结果表明:MgO和In2O3间可形成有限固溶体In2-xMgxO3(0≤x≤0.40);MgIn×电离的空穴对材料导带电子的湮灭,使掺镁纳米粉的电导变得很小;n(Mg2+):n(In3+)=1:2共沉淀物于900℃下热处理4 h,用所得的纳米粉制作的传感器在320～370℃下,对45μmol/L C2H5OH的灵敏度达102.5,为相同浓度干扰气体Petrol的12倍多.     

Effect of sintering temperature on the structural, optical and electrical properties of sol–gel derived indium oxide thin films

Sol gel derived indium oxide, In₂O₃; films were prepared by spin coating technique. The films were dried and sintered at different sintering temperatures (300, 400, 450 and 500 °C) in air. The effect of sintering temperature on the structural, optical and electrical properties of In₂O₃ thin films was studied. The morphology and structure of the films were analyzed by scanning electron microscope and X-ray diffraction. The films showed a bcc structure that changes its 400-preferential orientation to 222 orientation as the sintering temperature increases from 300 to 500 °C. The optical behavior of the films was studied by measuring the transmission spectra in the wavelength range 200–2,500 nm. Different optical models have been proposed for fitting the transmittance data and simulate the optical constants as well as the film thickness of In₂O₃ films. The best fitting of the data was obtained by combining the classical Drude and OJL models coupled with the Bruggeman effective medium approximation. The optical parameters of Drude model (plasma frequency and damping constant) are used calculate the electrical properties of the films. The calculated values of the electrical sheet resistance were compared with those measured experimentally by four probes. The correlation between the film orientation change and its optical and electrical properties was discussed.     

Influence of morphology and topography on potentiometric response of magnesium and calcium sensitive PEDOT films doped with adenosine triphosphate (ATP)

Poly(3,4-ethylenedioxythiophene) (PEDOT) films doped with adenosine triphosphate (ATP) are used to study the biologically relevant competitive magnesium and calcium ion-exchange at ATP membrane sites. It is shown, by atomic force microscopy (AFM) and scanning electron microscopy (SEM), that the surface topography and morphology of the PEDOT-ATP films determines the quality of their potentiometric response. More smooth and less rough films result in better potentiometric characteristics, particularly in a faster response. The topography/morphology of the PEDOT-ATP films is influenced by conditions during electrodeposition (electrochemical method of deposition, pH, concentration of electrolytes) and post-deposition soaking (including net-time of soaking), as evidenced by X-ray photoelectron spectroscopy (XPS) and energy dispersive analysis of X-rays (EDAX).     

Adsorption of Cr(VI) and Se(IV) from their aqueous solutions onto Zr4+-substituted ZnAl/MgAl-layered double hydroxides: effect of Zr4+ substitution in the layer

Hydrotalcite-like compounds (layered double hydroxides, LDHs) containing varying amounts of Al(3+), Zr(4+), and Zn(2+) or Mg(2+) in the metal hydroxide layer have been synthesized and characterized by various physicochemical methods. The adsorption behavior of uncalcined (as-synthesized) and calcined LDHs have been investigated for Cr(2)O(7)(2-) and SeO(3)(2-). The mixed oxides, obtained on calcination at 450 degrees C, exhibit high adsorption capacities for Cr(2)O(7)(2-) (1.6-2.7 meq/g) and SeO(3)(2-) (1.1-1.5 meq/g), where adsorption occurs through rehydration. Substitution of Zr(4+) in the LDHs, for either M(2+) or Al(3+) ions, increases the adsorption capacity up to 20%, thus providing an alternative way to enhance the adsorption capacity of this type of material. The high adsorption capacity of these materials could be successfully used for removal of undesirable anions from water and also for synthesis of intercalated materials with tailored acidobasicity.     

Nitrogen Plasma Enhanced Low Temperature Atomic Layer Deposition of Magnesium Phosphorus Oxynitride (MgPON) Solid-State Electrolytes

Solid-state batteries (SSBs) that use solid electrolytes instead of flammable liquid electrolytes have the potential to generate higher specific capacity and offer better safety. Magnesium (Mg) based SSBs with Mg metal anodes are considered to be one of the most promising energy storage candidates, because it gives high theoretical volumetric capacities of 3830 mAh cm⁻³. Here, we demonstrate an atomic layer deposition (ALD) process with a double nitrogen plasma process that successfully produces nitrogen-incorporated magnesium phosphorus oxynitride (MgPON) solid-state electrolyte (SSE) thin films at a low deposition temperature of 125 °C. The ALD MgPON SSEs exhibit an ionic conductivity of 0.36 and 1.2 μS cm⁻¹ at 450 and 500 °C, respectively. The proposed ALD strategy shows the ability of conformal deposition nitrogen-doped SSEs on pattered substrates and is attractive for using nitride ion-conducing films as protective or wetting interlayers in solid-state Mg and Li batteries.     

LaCo(1-x)Ni(x)O(3) with Improved Electrical Conductivity

To determine the applicability of LaCo(1-x)Ni(x)O(3) in a conductive material for electrical wiring, the dependence of the electronic transport property on the Ni content is investigated via Hall effect measurements, Rietveld analyses, and band-structure calculations. Ni doping (50 mol %) into the Co sites realizes a high electrical conductivity of 1.9 × 10(3) S/cm, which is an unexpectedly high value for a LaCo(1-x)Ni(x)O(3) system, at room temperature due to the high carrier concentration of 2.2 × 10(22) cm(-3) and the small effective mass of 0.1 m(e). In addition, the high electrical conductivity is maintained from room temperature to 900 °C; that is, the temperature coefficient of the conductivity is smaller than that of standard metals. Thus, the results indicate that LaCo(0.5)Ni(0.5)O(3) is suitable as a conductive material for electrical wiring at high temperatures in air.     

An investigation of the microstructure,optical and electrical properties of ZITO thin film using the sol–gel method

The multi-compound ZITO transparent conductive oxide (TCO) thin films were synthesized using the sol–gel method. The ZITO thin films with various volume ratios of ZnO to ITO (1:1, 2:1 and 9:1) were crystallized at different temperatures (600–700 °C). The results showed that the crystalline characteristics and optical transmittance were mainly dependent on ITO content and crystallization. Notably, the 650 °C Z₉ITO film not only had better conductivity but also possessed excellent optical transmittance. In addition, the surface roughness of the ZITO films and optoelectric properties of IZO (indium doped ZnO) films were analyzed to confirm the contribution of indium dopants on the optical transmittance. Also, the ZITO films were subjected to the effects of indium and tin dopants and this improved the related characteristics of ZnO films.     

纳米阻燃氢氧化镁/聚氧化乙烯复合聚合物电解质

合成了纳米氢氧化镁作为聚氧化乙烯(PEO)基聚合物电解质的增塑剂和阻燃剂,并对其进行X射线衍射(XRD)、透射电子显微镜(TEM)和热重(TG)分析研究.制得的氢氧化镁为片状六方晶体,尺寸在50-80nm之间,纳米氢氧化镁在340℃时开始热分解.对纳米氢氧化镁/PEO复合聚合物电解质的电化学研究结果显示:纳米氢氧化镁/PEO复合聚合物电解质的离子电导率随着添加纳米氢氧化镁的质量分数的增加先增大后减小,其在5%-10%之间时,复合聚合物电解质的离子电导率达到最大值.纳米氢氧化镁的添加使复合聚合物电解质的阳极氧化电位有一定程度的提高,纳米氢氧化镁具有改善PEO阳极抗氧化能力的作用.     

Layer-by-layer assembled multilayer TiO(x) for efficient electron acceptor in polymer hybrid solar cells

We demonstrate that TiO(x) nanocomposite films fabricated using electrostatic layer-by-layer (LbL) assembly improve the power conversion efficiency of photovoltaic cells compared to conventional TiO(x) films fabricated via the sol-gel process. For this study, titanium precursor/poly(allylamine hydrochloride) (PAH) multilayer films were first deposited onto indium tin oxide-coated glass to produce TiO(x) nanocomposites (TiO(x)NC). The specific effect of the LbL processed TiO(x) on photovoltaic performance was investigated using the planar bilayer TiO(x)NC and highly regioregular poly(3-hexylthiophene) (P3HT) solar cells, and the P3HT/LbL TiO(x)NC solar cells showed a dramatic increase in power efficiency, particularly in terms of the short current density and fill factor. The improved efficiency of this device is mainly due to the difference in the chemical composition of the LbL TiO(x)NC films, including the much higher Ti(3+)/Ti(4+) ratio and the highly reactive facets of crystals as demonstrated by XPS and XRD measurement, thus enhancing the electron transfer between electron donors and acceptors. In addition, the grazing incidence wide-angle X-ray scattering (GIWAXS) study revealed the presence of more highly oriented P3HT stacks parallel to the substrate on the LbL TiO(x)NC film compared to those on the sol-gel TiO(x) films, possibly influencing the hole mobility of P3HT and the energy transfer near and at the interface between the P3HT and TiO(x) layers. The results of this study demonstrate that this approach is a promising one for the design of hybrid solar cells with improved efficiency.     

Cation mobility and kinetics of ion exchange in zirconium hydrogen monothiophosphate hydrate, Zr(HPO(3)S)(2)x1.5H(2)O

The ion conductivity of zirconium hydrogen monothiophosphate (Zr(HPO(3)S)(2)x1.5H(2)O) has been measured by impedance spectroscopy. The measured value of proton conductivity is 3 x 10(-5) S/cm at 298 K. Conductivity was shown to decrease with increasing temperature due to a dehydration process. Above 450 K, the conductivity is likely governed by proton transport in the anhydrous phase Zr(HPO(3)S)(2). The activation energies of proton conductivity were measured to be 18 +/- 2 kJ/mol for Zr(HPO(3)S)(2)x1.5H(2)O and 60 +/- 3 kJ/mol for the anhydrous compound. The kinetics of ion exchange was studied with the use of potentiometric titration for several ion pairs, H(+)/Na(+), H(+)/Zn(2+), and Na(+)/Zn(2+) in Zr(HPO(3)S)(2)x1.5H(2)O. The diffusion coefficient values for H(+)/Na(+) ion exchange in Zr(HPO(3)S)(2)x1.5H(2)O are lower than those reported in alpha-zirconium phosphate. At the same time, the mobility of zinc ions in Zr(HPO(3)S)(2)x1.5H(2)O is higher than sodium ion mobility. The ion exchange H(+)/Zn(2+) is accompanied by the slow hydrolysis of the initial compound. In all cases, the powdered solids were evaluated by powder X-ray diffraction, and particle sizes were controlled by grinding and sieving the powders.