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Organic molecule (Histidine) embedded cadmium sulfide (CdS) nanocomposites are prepared by the solvothermal method. CdS nanocomposite, prepared with 1:1 M ratio of S2− to Cd2+, shows the highest crystallinity and highest hydrogen production via water splitting. Optimization of Pt deposition indicates that 5.5 wt% of Pt deposition on CdS nanocomposite produces the highest amount of H2 gas. Moreover, the contents of histidine in CdS were changed from 0.0 to 2.5 mmol, and the result shows that CdS nanocomposite with 1 mmol of histidine has the highest rate of hydrogen production (21.35 mmol/g/h). This is one of the highest rates of hydrogen production from a single semiconductor photocatalyst system under visible light irradiation. These results indicate that organic molecules embedded CdS nanocomposites could be a promising photocatalyst for hydrogen production via water splitting.

We report on the magnetic and optical properties of DyFe0.5Cr0.5O3 nanoparticles synthesized by a sol–gel method. Rietveld refinement of a powder X-ray diffraction (XRD) pattern confirms the formation of an orthorhombic disordered phase with the Pnma space group. The formation of nano-sized particles, with an average size of 42(±12) nm, was approximated by the transmission electron microscopy (TEM) image analysis. X-ray photoelectron spectroscopy (XPS) of this compound reveals the presence of Fe2+/Fe3+ and Cr2+/Cr3+ mixed-valence states as a consequence of oxygen vacancies present at the surface of nanoparticles. The temperature-dependent magnetization (M–T) shows a finite non-zero magnetization up to 300 K and the field-dependent magnetization (M–H) curve exhibits a weak ferromagnetic (WFM) nature at 300 K with a clear hysteresis loop, which is quite appealing compared to that of the previously reported micron-sized DyFe0.5Cr0.5O3. These observations indicate that the large concentration of uncompensated surface spin of nanoparticles could be responsible for the observed room-temperature ferromagnetism. Moreover, DyFe0.5Cr0.5O3 nanoparticles show a significantly narrow band gap (Eg ∼ 2.0 eV). Meanwhile, the oxygen vacancies may generate shallow trap energy levels within the band gap as observed from photoluminescence (PL) spectroscopy. The observed band gap narrowing by Fe doping and the effect of oxygen vacancies on the band gap are consistent with the predictions of density functional theory (DFT) calculations. The evidence of room-temperature ferromagnetism in DyFe0.5Cr0.5O3 nanoparticles compared to their bulk counterparts and the significantly narrow band gap in the visible range manifest the potential of this material in spintronic and optical applications.

Multilayer antireflection coatings (ARCs) for solar cells are conventionally designed to enhance the photocurrent level obtained at normal incidence. This is mainly because outdoor solar panels are usually placed such that they can receive strong midday sunlight at a nearly vertical angle. However, in the case of indoor photovoltaic devices, the direction of light changes considerably with changes in the relative position and angle between the device and light sources; therefore, it is often difficult to predict the incident angle. In this study, we explore a method to design ARCs suitable for indoor photovoltaics by essentially taking into account the indoor lighting environment, which is different from the outdoor conditions. We propose an optimization-based design strategy that aims to enhance the average level of the photocurrent generated when a solar cell receives irradiance randomly from all directions. We apply the proposed method to design an ARC for organic photovoltaics, which are expected to be promising indoor devices, and numerically compare the resultant performance with that obtained using a conventional design method. The results demonstrate that our design strategy is effective for achieving excellent omnidirectional antireflection performance and allows the realization of practical and efficient ARCs for indoor devices.

In Bangladesh, India, and Pakistan the ship breaking (SB) sector dismantles end-of-life ships on open beaches, exposing the environment to the resulting pollution, especially the soil and water. Because SB occurs in the vicinity of other poorly-regulated activities in industrial zones (IZ) in these countries, there is some ambiguity concerning the relative roles played by SB and IZ in the accumulation of hazardous materials in the soil. In the absence of comparative studies, this study investigated the relative levels of soil contamination due to SB or IZ in the same geographic region by taking soil samples from SB and unrelated IZs in Chittagong, Bangladesh. The technogenic input of sixty-four chemical elements into the soil at the SB or IZ were compared with off-site reference values or the natural content of these elements in the Earth's crust and surface. The magnitude of soil contamination by ecotoxic elements, the corresponding bioavailability, and the ecological risks were assessed based on the regulatory reference values (RRVs) and with other approaches using data aggregation. Among the different potentially toxic elements, Cr, Cu, Ni, Pb, and Zn were found to be above the maximum allowable concentration (p

Multiple layers of aluminum silicate and SiO2 are deposited at room temperature (RT) by repeating a combination of aluminum-silicate atomic layer deposition (ALD) and a plural number of SiO2 ALDs. The RT-ALD is performed by using precursors of tris(dimethylamino)silane and trimethyl aluminum (TMA). The oxidizing gas is plasma excited humidified Ar. A cross-sectional transmission electron microscope and angle resolved x-ray photoelectron spectroscopy suggest that aluminum from the TMA molecule is diffused to SiO2 to form an aluminum silicate layer with the Al rich surface at RT. The deposited film shows an enhanced Na sorption in an NaCl aqueous solution of 10 mM, compared with the pure aluminum silicate layer without the SiO2 layer. It is assumed that the bond formation of Al–O–Al in the aluminum silicate film is suppressed by limiting the thickness of the aluminum silicate layer. Multiple films are also applicable for Cs and K ion sorption. The effects of the multiple layers on the ion sorptivity are discussed in the paper.

We report on the magnetic and optical properties of DyFe0.5Cr0.5O3 nanoparticles synthesized by a sol-gel method. Rietveld refinement of a powder X-ray diffraction (XRD) pattern confirms the formation of an orthorhombic disordered phase with the Pnma space group. The formation of nano-sized particles, with an average size of 42(±12) nm, was approximated by the transmission electron microscopy (TEM) image analysis. X-ray photoelectron spectroscopy (XPS) of this compound reveals the presence of Fe2+/Fe3+ and Cr2+/Cr3+ mixed-valence states as a consequence of oxygen vacancies present at the surface of nanoparticles. The temperature-dependent magnetization (M-T) shows a finite non-zero magnetization up to 300 K and the field-dependent magnetization (M-H) curve exhibits a weak ferromagnetic (WFM) nature at 300 K with a clear hysteresis loop, which is quite appealing compared to that of the previously reported micron-sized DyFe0.5Cr0.5O3. These observations indicate that the large concentration of uncompensated surface spin of nanoparticles could be responsible for the observed room-temperature ferromagnetism. Moreover, DyFe0.5Cr0.5O3 nanoparticles show a significantly narrow band gap (Eg ∼ 2.0 eV). Meanwhile, the oxygen vacancies may generate shallow trap energy levels within the band gap as observed from photoluminescence (PL) spectroscopy. The observed band gap narrowing by Fe doping and the effect of oxygen vacancies on the band gap are consistent with the predictions of density functional theory (DFT) calculations. The evidence of room-temperature ferromagnetism in DyFe0.5Cr0.5O3 nanoparticles compared to their bulk counterparts and the significantly narrow band gap in the visible range manifest the potential of this material in spintronic and optical applications.

The spread of power saving devices hold success throughout the world. But to make the demand side power management more efficient and less waste, control of this sector is mandatory. Here, web-based portable data acquisition and control system has been implemented in small scale. This experiment has been done influencing from an existing advanced supervisory control and data acquisition system research; having XPSU, XCU, PBU, DS and ASC. To monitor the huge electricity demand with both manual and automatic control, this experiment will be helpful for any area, building or workstation. Implementation of this type of system is less costly than existing SCADA technologies for demand side. Beside the additional features, the data acquisition error rate has been reduced and switching time has been calibrated in this experiment.

Room-temperature atomic layer deposition (RT-ALD) of iron oxide is developed with a precursor of bis(N, N′-diisopropyl-propionamidinate)iron [(DIPPA)2Fe] and plasma excited humidified Ar. Saturated conditions of (DIPPA)2Fe and plasma excited humidified Ar exposures at room temperature (23–25 °C) are investigated by in situ IR absorption spectroscopy for finding the RT-ALD process condition. Using the designated process, the growth per cycle of the iron oxide RT-ALD is confirmed as 0.15 nm/cycle based on the film thicknesses measured by the spectroscopic ellipsometer. The x-ray photoelectron spectroscopy suggests that the stoichiometry of the deposited iron oxide is closed to that of Fe2O3. The grown film is composed of partly crystallized iron oxides, confirmed by cross-sectional TEM and AFM. The RT deposited iron oxide exhibits a magnetic volume susceptibility of 1.52, which implies the applicability of the present coating for magnetic drug delivery. We discuss the surface reaction with the IR absorption spectroscopy and the quartz crystal microbalance. The (DIPPA)2Fe molecule is suggested to adsorb on the Fe2O3 surface with mixed first- and second-order reactions at RT. It is also suggested that amidinate ligands in (DIPPA)2Fe are released in the course of the adsorption and the remaining ligands are oxidized by the plasma excited humidified Ar. The RT iron oxide deposition is demonstrated, and the reaction mechanism of room-temperature ALD is discussed in this paper.

We propose a new antireflection (AR) design for organic photovoltaics (OPVs) to achieve broadband and omnidirectional enhancement of photocurrent. In the proposed design, a hybrid AR structure, which combines moth eye texturing and two-layer interference coating, is integrated with a glass substrate having a high refractive index (n). Using the optical simulation for OPV cells, we compare the performance of various AR configurations upon changing the refractive index of the glass substrate. We show that the short-circuit current density ( $$J_{SC}$$ ) is decreased by using the high-n glass substrate without AR coating, whereas $$J_{SC}$$ is significantly increased by applying the high-n glass substrate with the hybrid AR structure, suggesting an importance of the integrated design. In addition, we demonstrate that the proposed AR configuration is quite effective to attain broad angle performance and is robust against the variations in geometric features of moth eye texture. Finally, the spectral dependence of photocurrent generation is experimentally measured for the verification of the effectiveness of the integrated AR design. These results provide a practical and efficient AR technique that can further expand the potential of OPVs as energy supply devices.

Nanothick TiO2 channel-thin film transistors (TFTs) are examined as UV and gas sensors. The TiO2 thin films were deposited by atomic layer deposition on thermally oxidized n+ Si substrates with deposition thicknesses from 17 to 42 nm, where the channel length and width were fixed at 60 μm and 1 mm, respectively. The titanium drain and source electrodes were fabricated on the TiO2 channel and the n+ Si substrate was used as the gate electrode. The nanothick TiO2-channel TFT exhibits an extremely high drain current modulation of ∼20 μA in the atmosphere with a UV exposure of 1.6 × 10−5 W cm−2 and a wavelength of 278 nm. This corresponds to a UV sensitivity of 2 × 103 A W−1. The strong drain current modulation by the UV light is explained not only with the direct absorption of the UV photons in the channel but also with the surface interactions with gas molecules in the atmosphere. In the course of the mechanism study about the UV sensing, we confirm the strong modulation of the drain current with various ambience of air, dry air, N2, and vacuum, suggesting a possibility as the gas sensor in the dark. The operation mechanism of the nanothick TiO2 TFT is discussed in this paper.

Room-temperature atomic layer deposition (ALD) of ZrO2 is developed with tetrakis(ethylmethylamino)zirconium (TEMAZ) and a plasma-excited humidified argon. A growth per cycle of 0.17 nm/cycle at room temperature is confirmed, and the TEMAZ adsorption and its oxidization on ZrO2 are characterized by IR absorption spectroscopy with a multiple internal reflection mode. TEMAZ is saturated on a ZrO2 surface with exposures exceeding ∼2.0 × 105 Langmuir (1 Langmuir = 1.0 × 10−6 Torr s) at room temperature, and the plasma-excited humidified argon is effective in oxidizing the TEMAZ-adsorbed ZrO2 surface. The IR absorption spectroscopy suggests that Zr-OH works as an adsorption site for TEMAZ. The reaction mechanism of room-temperature ZrO2 ALD is discussed in this paper.

Pure cadmium sulfide and histidine decorated cadmium sulfide nanocomposites are prepared by the hydrothermal or solvothermal method. Scanning electron microscopy (SEM) analysis shows that the particle sizes of pure cadmium sulfide (pu/CdS) and histidine decorated cadmium sulfide prepared by the hydrothermal method (hi/CdS) range from 0.75 to 3.0 &mu, m. However, when a solvothermal method is used, the particle size of histidine decorated cadmium sulfide (so/CdS) ranges from 50 to 300 nm. X-ray diffraction (XRD) patterns show that all samples (pu/CdS, hi/CdS and so/CdS) have a hexagonal wurtzite crystal structure but so/CdS has a poor crystallinity compared to the others. The as-prepared samples are applied to photocatalytic hydrogen production via water splitting and the results show that the highest H2 evolution rate for pu/CdS and hi/CdS are 1250 and 1950 &mu, mol&middot, g&minus, 1&middot, h&minus, 1, respectively. On the other hand, the so/CdS sample has a rate of 6020 &mu, 1, which is about five times higher than that of the pu/CdS sample. The increased specific surface area of so/CdS nanoparticles and effective charge separation by histidine molecules are attributed to the improved H2 evolution.

Aluminum nitride (AlN) has been attracting much attention since it has a wide direct transition band gap of 6.3 eV and it is applicable for UV-LEDs. The AlN films have been deposited by chemical vapor deposition (CVD) and atomic layer deposition (ALD). These conventional processes were performed at a temperature of 300 °C and higher. To apply the AlN coating on flexible films, the low temperature deposition process has been demanded. To demonstrate the AlN deposition at RT, an RT-ALD of AlN using trimethylaluminum (TMA) as an Al precursor and plasma-excited ammonia are studied based on study on multiple internal reflection infrared spectroscopy (MIR-IRAS). An n-type Si substrate was used as a prism for MIR-IRAS. The size of prism was 10×45 mm2 and its resistivity was 1000 Ωcm. 45° bevels on each of the short edges were formed. The prism was set in a reaction chamber for the ALD. If the IR spectra before and after the processes are defined as Ir and I0, respectively, we can calculate the absorbance (Abs) from the equation, Abs = log10(Ir/I0). TMA was used as the Al precursor. In the nitridation step, ammonia and argon was mixed with a volume ratio of 7:3, followed by being excited through a quartz tube with an RF power of 250 W and a frequency of 13.56 MHz. The flow rate of the mixed gas was 10 sccm. Ammonia molecules in the mixture were dissociated to NH radicals and some fragments. Plasma excited ammonia was provided in the chamber. We observed the surface reaction to confirm TMA adsorption and examine if the plasma-excited ammonia generated nitride on the TMA adsorbed surfaces. Fig. 1 shows IR spectra were obtained from a TMA adsorbed surface with exposures from 1000 to 400000 L at RT. Peaks at 2933, 2894, and 2829 cm-1 correspond to C-H vibrations in TMA. The positive peak indicates that the TMA was adsorbed on the surface at RT. Fig. 2 shows IR spectra measured from plasma excited ammonia treated TMA saturated surface. Negative peaks at 2933, 2894, and 2829 cm-1 suggests that the nitride was generated there at RT. We also confirmed the presence of AlN on the prism by an Al 2p peak at 73.3 eV and a N 1s peak at 398.1 eV by X-ray photoelectron spectroscopy. These suggests that it is possible to deposit AlN at RT. Figure 1

Fundamental surface reactions in the atomic layer deposition of GaN with trimethylgallium (TMG) and plasma-excited NH 3 are investigated by multiple-internal-reflection infrared absorption spectroscopy (MIR-IRAS) at surface temperatures varying from room temperature (RT) to 400 °C. It is found that TMG is saturated at RT on GaN surfaces when the TMG exposure exceeds 8 × 10 4 Langmuir (L), where 1 L corresponds to 1.33 × 10 −4 Pa s (or 1.0 × 10 −6 Torr s), and its saturation density reaches the maximum value at RT. Nitridation with the plasma-excited NH 3 on the TMG-saturated GaN surface is investigated by X-ray photoelectron spectroscopy (XPS). The nitridation becomes effective at surface temperatures in excess of 100 °C. The reaction models of TMG adsorption and nitridation on the GaN surface are proposed in this paper. Based on the surface analysis, a temperature-controlled ALD process consisting of RT-TMG adsorption and nitridation at 115 °C is examined, where the growth per cycle of 0.045 nm/cycle is confirmed. XPS analysis indicates that all N atoms are bonded as GaN. Atomic force microscopy indicates an average roughness of 0.23 nm. We discuss the reaction mechanism of GaN ALD in the low-temperature region at around 115 °C with TMG and plasma-excited NH 3 .

To improve the power conversion efficacy of organic photovoltaics (OPVs), it is required to design antireflection structures that could realize efficient and broadband light trapping. In this article, we perform global optimization of the textured pattern of moth eye antireflection surfaces to maximize the short-circuit current density (J SC) of OPVs with a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-based bulk heterojunction. We introduce an optimization algorithm consisting of two steps: in the first step, the simple grid search is conducted to roughly estimate a globally optimal solution, while in the second step, the Hooke and Jeeves pattern search is executed to refine the solution. By combining the optimization algorithm with the optical simulation based on the finite-difference time-domain method, we find the optimal period and height of moth eye array with which the level of J SC can be increased by 9.05% in the P3HT:PCBM-based organic solar cell. We also demonstrate that the optimized moth eye structure can significantly modify the light path at a long wavelength range to strengthen the electric field intensity and enhance energy absorption within the active layer.

This article discusses the hydrothermal synthesis of well-dispersed faceted α-GaOOH in the presence of sodium acetate by the self-assembly method. The synthesized α-GaOOH possesses a mixture of hexagonal and rectangular plates, cubic and diamond-like morphologies. The presence of ethanol as a co-solvent with water (1:1) facilitates scroll-like cylindrical morphology. The influences of sodium acetate concentration, hydrothermal temperatures, time and solvent on the formation of the above-mentioned morphologies were investigated. The synthesized α-GaOOH was characterized using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM) and High-Resolution Transmission Electron Microscopy (HR-TEM), thermal analysis and nitrogen adsorption analysis. The XRD pattern confirmed the formation of orthorhombic α-GaOOH. The increase of the sodium acetate concentration from 0.031 mol/L to 0.250 mol/L facilitates the formation of more cubic and diamond-shaped particles than plate-like particles. The formation of faceted α-GaOOH is slow at 150 degrees C, and a further increase in hydrothermal temperature from 175 degrees C to 225 degrees C had no appreciable effect. Similarly, an increase in hydrothermal time from 5 h to 20 h at 200 degrees C facilitates hexagonal to cubic shaped plates. The solution pH strongly influenced the aspect ratio of the nanoplates. Hydrothermal temperature and time had no appreciable effect from 175 degrees C to 225 degrees C. The removal perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) using the synthesized α-GaOOH was studied. A plausible mechanism for the formation of nanoplates is proposed.

The mesoporous α-GaOOH was synthesized using oxalic acid in a hydrothermal process at various hydrothermal temperatures and times. The nitrogen adsorption analysis indicated that α-GaOOH with surface areas ranging from 6 to 87 m2/g and pore sizes from 3.8 to 7.2 nm can be prepared by adjusting the experimental conditions. The photocatalytic hexavalent chromium reduction was studied under UV light irradiation and the results showed that α-GaOOH having higher surface area owned higher photocatalytic activity. The degradation of 2-ethoxy ethyl acetate in catalytic ozonation process showed that the degradation was enhanced over ozonation process in the presence of mesoporous α-GaOOH.

Dielectric and magnetic properties of BiFeO3 samples, co-doped with Gd or Ba and Ti in place of Bi and Fe, respectively, were investigated. The bulk powder samples of nominal compositions of Bi0.9Gd0.1Fe1–xTixO3 and Bi0.7Ba0.3Fe1-xTixO3 (x=0.00-0.25) ceramics were synthesized by conventional solid state reaction technique. The as prepared ceramics showed improved dielectric and magnetic properties. Also, ultrafine nanoparticles of the samples were prepared by milling assisted ultrasonic fragmentation of the bulk powder. The particles size was studied as a function of sonication time with TEM imaging and electron diffraction. These confirmed the formation of a large fraction of single-crystalline Bi0.9Gd0.1Fe1–xTixO3 nanoparticles with a mean size of 11-13 nm. The synthesized nanoparticles exhibit an improved magnetic behavior compared to their bulk counterparts at room temperature. The preparation and characterization of bulk ceramics as well as their nanoparticles were reported.

The synthesis as well as structural, multiferroic and optical characterization of Dy doped BiFeO$_3$ multiferroic ceramic are presented. Bulk polycrystalline Bi$_{0.9}$Dy$_{0.1}$FeO$_3$ sample is synthesized by solid state reaction, while their nano counterparts are prepared using ultrasonic probe sonication technique. Significant improvement of phase purity in the as synthesized samples is observed after the doping of Dy both in bulk Bi$_{0.9}$Dy$_{0.1}$FeO$_3$ sample and corresponding nanoparticles as evidenced from Rietveld refinement. Magnetization measurements using SQUID magnetometer exhibit enhanced magnetic properties for Dy doped bulk Bi$_{0.9}$Dy$_{0.1}$FeO$_3$ ceramic compared to their nanostructured counterparts as well as undoped BiFeO$_3$. Within the applied field range, saturation polarization is observed for Bi$_{0.9}$Dy$_{0.1}$FeO$_3$ bulk ceramic only. As a result, intrinsic ferroelectric behavior is obtained just for this sample. Optical bandgap measurements reveal lower bandgap for Dy doped bulk Bi$_{0.9}$Dy$_{0.1}$FeO$_3$ ceramic compared to that of corresponding nanoparticles and undoped BiFeO$_3$. The outcome of this investigation demonstrates the potential of Dy as a doping element in BiFeO$_3$ that provides a bulk ceramic material with improved multiferroic and optical properties compared to those of corresponding nanoparticles which involve rigorous synthesis procedure., Comment: 8 Pages, 8 figures

A simple route to prepare Gd$_{0.7}$Sr$_{0.3}$MnO$_3$ nanoparticles by ultrasonication of their bulk powder materials is presented in this article. For comparison, Gd$_{0.7}$Sr$_{0.3}$MnO$_3$ nanoparticles are also prepared by ball milling. The prepared samples are characterized by X-ray diffraction (XRD),field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscope (XPS), and Superconducting Quantum Interference Device (SQUID) magnetometer. XRD Rietveld analysis is carried out extensively for the determination of crystallographic parameters and the amount of crystalline and amorphous phases. FESEM images demonstrate the formation of nanoparticles with average particle size in the range of 50-100 nm for both ultrasonication and 4 hours (h) of ball milling. The bulk materials and nanoparticles synthesized by both ultrasonication and 4 h ball milling exhibit a paramagnetic to spin-glass transition. However, nanoparticles synthesized by 8 h and 12 h ball milling do not reveal any phase transition, rather show an upturn of magnetization at low temperature. The degradation of the magnetic properties in ball milled nanoparticles may be associated with amorphization of the nanoparticles due to ball milling particularly for milling time exceeding 8 h. This investigation demonstrates the potential of ultrasonication as a simple route to prepare high crystalline rare-earth based manganite nanoparticles with improved control compared to the traditional ball milling technique., Comment: 9 pages, 6 figures

Bioplastic based on starch as the matrix and cellulose nanocrystals from rice straw as reinforcing filler were prepared in this study. The isolation of cellulose nanocrystal (CNC) followed a series of steps: delignification, sulfuric acid hydrolysis, and sonication. The process afforded short, rod-like CNCs with particle diameter ranging from 10 to 12 nm and crystallinity index of 76.1%. Fourier transform infrared analysis of the CNCs also confirmed absorption patterns typical of cellulose and the removal of silica. Bioplastic with different starch-to-CNC ratios were prepared by solution casting and evaporation method. Scanning electron micrographs of the films showed uniform dispersion of CNC in the starch matrix. Mechanical tests revealed that both tensile strength and modulus significantly increased with increasing CNC load while percent elongation decreased. The moisture uptake of the films reinforced with CNC also decreased an indication of improvement in water resistance. However, the thermal stability of the films decreased by the addition of CNC.

We propose a hybrid antireflection structure (ARS), which integrates moth eye texturing and multilayer interference coating, to improve efficiency of organic photovoltaic (OPV) solar cells. We perform nearly global optimization of the geometric parameters characterizing the hybrid ARS, by using optical simulations based on the finite-difference time-domain method. The proposed optimization algorithm consists of two steps: in the first step, only the moth eye structure is globally optimized and, in the second step, the whole hybrid structure is optimized efficiently based on the results of the first step. Thus, the optimal moth eye structure is additionally obtained as an intermediate result. By applying this optimization method to an organic thin film solar cell, we show that the short-circuit current density (JSC) is increased by 8.90% with the moth eye structure and by 9.89% with the hybrid ARS. We also study the sensitivity of photocurrent to the geometric parameters of hybrid ARS, and the change in the spatial distribution of electric field intensity by the ARS. The results show that the hybridization of the two types of light trapping techniques is effective to reduce the inhomogeneity in the electric field distribution and obtain higher electric intensity in almost the whole active layer. The design concept of the hybrid ARS is quite useful for improving light trapping in OPVs and allows for extending the options available for broadband antireflection.

Room-temperature atomic layer deposition (ALD) of TiO 2 was developed using tetrakis(dimethylamino)titanium (TDMAT) and a remote-plasma-excited water vapor. A growth rate of 0.157 nm/cycle at room temperature was achieved, and the TDMAT adsorption and its oxidation on TiO 2 were investigated by multiple-internal-reflection infrared absorption spectroscopy. Saturated adsorption of the TDMAT occurs at exposures of ∼1 × 10 6 Langmuir (1 Langmuir = 1 × 10 −6 Torr s) at room temperature, and the remote-plasma-excited water vapor is effective in oxidizing the TDMAT-saturated TiO 2 surface. The IR study suggests that the Ti-OH plays a role of adsorption site for TDMAT. The reaction mechanism of room-temperature TiO 2 ALD is discussed.

Room-temperature SiO2 atomic layer deposition (ALD) on soft, flexible materials of acrylic resin and polystyrene is developed using tris (dimethylamino) silane and plasma-excited water vapor. The growth rate is measured to be 0.13 nm/cycle at room temperature on the acrylic resin surface. The SiO2 coating on the soft materials was examined by X-ray photoelectron spectroscopy and an organic solvent resistant test. This process is applicable as a surface treatment for improving chemical resistivity of the soft materials.

Metal-organic chemical vapor deposition (MOCVD) method has been applied to grow nanostructured ZnO films on Si (100) substrate at temperatures ranging from 200 to 550 °C. The as-prepared films were characterized by XRD, SEM, XPS analysis. The growth rate of ZnO films increases with increasing the deposition temperatures. The deposition temperatures have a drastic effect on the crystallinity and morphology of the nanostructured ZnO. Whisker shaped ZnO is formed at a temperature of 350 °C. The deposition time also affects the morphology of the particles. At 400 °C, sample with one hour deposition forms whisker shaped ZnO nanostructures whereas that of with two hours deposition forms flower-like nanostructures.

Room temperature (RT) atomic layer deposition (ALD) of Nb2O5 is developed using (tert-butylimido)tris(ethylmethylamido)niobium and a plasma excited humidified Ar. To design the process condition, an in situ monitoring system of IR absorption spectroscopy (IRAS) is utilized to observe the surface saturation of precursors. Based on the saturation characteristics of precursors measured from IRAS, the gas injection condition and oxidization time are determined, where the RT Nb2O5 deposition with a growth per cycle of 0.11 nm is confirmed by x-ray photoelectron spectroscopy and spectroscopic ellipsometry. The RT deposited Nb2O5 film exhibits clear anticorrosion to hydrochloric acid. The reaction mechanism of ALD growth and the applicability of anticorrosion film with RT deposited N2O5 are discussed in this paper.

A three-phase solid-state solar cell (SSSC) has been developed successfully using TaON nanoparticles or BiOI microspheres as a sensitizer material over a TiO2 film and CuI as a hole collector. Stable current (Isc)–voltage (Voc) curves are found under ultraviolet UV visible light irradiation with an efficiency of 0.15% and 0.10% for TaON- and BiOI-based solar cells, respectively. The observed photocurrents in SSSCs are approximately 10 and 48 times higher than those in wet-type solar cells (WSCs) based on TaON and BiOI, respectively. A plausible mechanism of charge transfer and hole filling is discussed in terms of the band gap energy and band position of the semiconductor materials.

Natural dolomite was calcined at different temperatures in the range 873–1373 K and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption/desorption isotherm. The calcination temperature had considerable effect on the surface chemical composition, crystallinity, and basicity of CO2 gas sorption of each component in the calcined products. The sorption isotherm of both in low and high concentrations of fluoride (F–) was investigated for selected calcination products. The sample calcined at 973 K was found to show the highest sorption density for F– at equilibrium concentrations lower than 0.5 mM, which was equivalent to the maximum concentration limit of F–. In this range, the principle of F– removal is mainly based on destructive hydration of MgO. At equilibrium concentrations of F– higher than 0.5 mM, the sorption process was controlled by precipitation of CaF2 and co-precipitation with Ca(OH)2 due to excess liberation of Ca2 ions from CaO. In this concentration region the products of calcination at higher temperatures are profitable for the immobilization of F–. Additionally, the effect of CO2 gas derived from carbonates on the reactivity of MgO to remove F– during calcination of natural dolomite was also discussed.

A green synthesis method for the preparation of mesoporous α-Fe 2 O 3 nanoparticles has been developed using the extract of green tea ( camellia sinensis ) leaves. This simple and one-step method can suitably be scaled up for large-scale synthesis. The as-prepared mesoporous nanoparticles were characterized by SEM, TEM, XRD, XPS, Raman, UV–visible spectroscopy and N 2 adsorption analysis. The nanoparticles were highly pure and well crystallized with an average particle size of 60 nm. The photocatalytic activity of nanoparticles was evaluated by the amount of hydroxyl radical formation under visible light irradiation detected by fluorescence spectroscopy. The as-prepared α-Fe 2 O 3 showed two times higher activity than commercial α-Fe 2 O 3 in term of hydroxyl radical formation and enhanced performance in a photoelectrochemical cell. Also, a plausible mechanism for the formation of mesoporous α-Fe 2 O 3 has been suggested.

The structural and ferroelectric properties of Dy doped BiFeO 3 multiferroic materials are reported. The bulk polycrystalline Bi 0.9 Dy 0.1 FeO 3 samples were synthesized using solid state reaction technique and their nano counterparts were prepared using ultrasonic probe sonication. XRD patterns demonstrated significant improvement of phase purity due to Dy substitution both in bulk sample and corresponding nanoparticles. Again, FESEM imaging was carried out to analyze the surface morphology of bulk sample as well as to determine the size and distribution of the synthesized nanoparticles. Furthermore, leakage current density measurements were performed where, interestingly, we found comparable performance for Bi 0.9 Dy 0.1 FeO 3 bulk and its corresponding nanoparticles. Moreover, the polarization versus electric field measurements showed higher remanent polarization and coercive field for nanoparticles compared to their bulk samples which might be associated with leaky behavior generated from oxygen related defects of the nanoparticles. However, saturation polarization within the applied field range was observed for Bi 0.9 Dy 0.1 FeO 3 bulk only indicating inherent ferroelectric behavior. Overall, this investigation provides evidence of Bi 0.9 Dy 0.1 FeO 3 multiferroic having enhanced structural purity and ferroelectric properties over undoped BiFeO 3 . In particular, it opens up the pathway of a material with equivalent bulk and nano leakage current performance which may be useful in many applications.

Pure BiFeO 3 nanoparticles were synthesized by a simple sol-gel method namely modified Pechini method. The nanoparticles were calcinated at four different temperatures (450°C, 550°C, 650°C, 750°C). Requirement for extra washing step for impurity phase reduction has been eliminated by elongation of the drying duration at oven from 12 hours to 28 hours along with intermediate grinding. FESEM and X-ray Diffraction (XRD) were performed which confirm that the samples calcinated at 450°C and 550°C show smaller particle size and greater correspondence. Hence XPS was performed on these two samples which showed lower oxygen vacancies for 550°C. Finally the SQUID analysis has been carried out for the 550°C sample. A higher value of remanent magnetization and coercive field at room temperature has been observed. Besides, an asymmetric shift in the field axis with unsaturated M-H curve may be attributed to the existence of exchange bias effect in the synthesized nanoparticles.