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The Europium (Eu(III))-doped Cu2ZnSnS4 (CZTS) thin films were prepared by spin coating method. Structural, morphological and elemental composition were analysed by X-ray Diffraction (XRD), Raman Spectroscopy and Scanning Electron Microscope with Energy-Dispersive X-ray analysis (SEM–EDX). Optoelectronic properties were analysed by UV–VIS-NIR Spectrophotometer and Van der Pauw Ecopia HMS-3000 Hall Measurement System. The XRD patterns verified the kesterite structure and Eu(III) doping was shown to increase crystallite sizes. High absorption was seen in the visible region of the UV–VIS-NIR spectra, and as the doping percentage was increased, the band gaps were dropping from 1.92 to 1.80 eV. The SEM images exhibited enhanced grain growth from several nano-meters to micrometers along with agglomeration of different sizes. The Hall measurements showed that the undoped CZTS and 1% Eu(III) doped CZTS as p-type semiconductors, suitable absorber layer of thin film solar cells, 2% and 3% Eu(III)-doped samples as n-type semiconductors. [ABSTRACT FROM AUTHOR]

Of late, there has been a tremendous surge in the development of field-effect transistors of various kinds because of their versatile nature of applications in the frontier fields of science and technology. Among them, metal oxide semiconducting field-effect transistors (MOSFET) offer cutting-edge technology in a cost-efficient way of fabricating the device, which focuses on enlarged active area and high area efficiency that could be achieved using simple fabrication processes. The top contact-bottom gate approach has been chosen for the fabrication of an Indium Zinc Oxide MOSFET utilizing silver (Ag) as the source and drain materials. High k-dielectric layer Al2O3 has been deposited onto the n-type phosphorus-doped silicon substrate, which functions as a gate layer. The fabrication process is entailed with the solution processing technique along with the spin coating process. Electrical characterization on the IZO MOSFET shows promising results in the field-effect mobility of 21.37 cm2 V−1 S−1, a subthreshold slope of 0.181 V/decade, and a threshold voltage of 1.2608 V, respectively. The electrical characterization was considered under different atmospheres like dark and daylight showcasing the photoresponsivity which leads to the possible potential for optoelectronic devices. Transport properties of the fabricated IZO MOSFET have been determined by Hall measurements which indicate an electron density of 0.343 × 1023 cm−3 as well as an electron mobility of 2.305 × 10−4 cm2 eV−1 S−1. The structural analyses have been investigated using X-ray diffraction and X-ray photoelectron spectroscopic techniques which could confirm the composition and the film quality of the fabricated materials on the substrate. Surface morphology and structural characterization of the thin film have been studied using SEM and AFM studies. Major applications of IZO MOSFET include power electronics such as power supplies, inverters, and motor control systems. [ABSTRACT FROM AUTHOR]

Demands for cheaper solar cells have led researchers to less complex, low-temperature, vacuum-free thin-film deposition processes, like spray pyrolysis and sol–gel spin coating. Previous studies of β-Ga2O3 thin-film deposition have used aqueous solutions of gallium nitrate which have strong tendencies to form hydroxide precipitates. This leads to the blockage of spray gun nozzles. To avoid precipitation, tetrahydroxogallate (III) ammonium was used as a novelty precursor in this study for the synthesis of β-Ga2O3. In the spray pyrolysis technique, the precursor was deposited on sapphire substrates at 200 ℃, with a carrier gas pressure of 200 kPa. The same precursor, with added monoethanolamine to enhance viscosity, was used in the spin coating method. A polycrystalline β-Ga2O3 structure was obtained by post-annealing films at 750 ℃ in ambient air. The spin-coated films with thicknesses ranging from 165 to 354 nm exhibited an average crystallite size of 17.78 nm and an optical band gap range between 4.80 eV and 4.95 eV. Films produced by spray pyrolysis had thicknesses ranging between 158 and 255 nm, an average crystallite size of 17.55 nm, and a band gap ranging between 4.69 eV and 4.93 eV. From Raman spectroscopy, the molecular vibrational modes Ag and Bg were detected, featuring three blue shifts and two red shifts. Films showed a UV-blue region originating from oxygen and gallium vacancies in the lattice, an important characteristic for good photodetectors and vital for solar cell passivation. When utilizing β-Ga2O3 as dielectric coating, the refractive index between air and solar cells is reduced, enhancing solar energy absorption. Similar results were obtained for both synthesis techniques confirming the reliability of the methods. [ABSTRACT FROM AUTHOR]

We have fabricated undoped ZnO and Mn-doped ZnO thin films on glass substrates using sol–gel spin coating method and investigated their structural, optical, magnetic and magnetoresistance properties depending on the Mn doping ratio. X-ray diffraction (XRD) patterns showed that all the films under study are predominantly crystalized in a single-phase wurtzite structure. Scanning electron microscope (SEM) images revealed that the films become more homogeneous, continuous and pinhole-free coatings as the Mn content of the films increases. Optical characterizations by UV–visible spectrometer indicated that transmittance spectra of all films have a high transmittance above 85% in visible region, while they show the absorbance spectra in 300–400 nm range. In addition, it was observed that the optical energy band edges shift to red with increasing Mn content, due to probably increasing the carrier concentration. The refractive index and the dielectric constant are also affect by the Mn content. Magnetic measurements by vibrating sample magnetometer showed that the film magnetic properties change from diamagnetic to ferromagnetic as the Mn content increases. Furthermore, it was found that the magnetoresistance measurements support their magnetic behavior of the films. [ABSTRACT FROM AUTHOR]

The poor conductivity of oxides such as TiO2 is the big challenge that severely restricts their applications in the gas sesnor field. The rational design of their electronic structure and nano/micro structure is an effective approach to solve this problem. The spin coating approach was used to create a combined strategy of MOF-derived TiO2 thin films in this work. Various characterization methods, such as XRD, Raman, TEM, and XPS analyses, were used to examine the produced sensor films. XRD and Tem results suggest that MOF could significantly improve the structural and morphological properties of TiO2. SEM and TEM clearly shows that TiO2 have nanoparticles and nanosheets morphologies and the spherical shaped individual nanoparticles sizes in the range of 25–35 nm was found in the TiO2 sample. Chemiresistive gas sensors made from this MOF-TiO2 had much better NO2-sensing capability than pristine TiO2, as well as higher sensitivity (response of 84.6% under 1000 ppm) and faster response and recovery times (45 s/57 s). The unique porous structure with high specific surface area and plentiful accessible active sites with surface-adsorbed oxygen is attributed to the MOF-derived TiO2 improved sensing capability. [ABSTRACT FROM AUTHOR]

Highly c-axis oriented undoped and antimony (Sb) doped zinc oxide (ZnO) thin films were deposited on a glass substrate by the sol–gel spin coating method. Six layers of deposition were repeated with 300 °C heat treatment for each layer then samples were annealed at 500 °C under an ambient atmosphere. Hall effect measurements revealed that 1%, 2%, and 3% Sb-doped ZnO samples presented p-type conductivity, while the 5% Sb-doped ZnO sample had n-type conductivity. Moreover, the resistivity of the samples was about in the order of 10 3 Ω cm . All of the deposited thin films have displayed high transparency, around 90%, implying that they are suitable for optoelectronic applications. Further, the near UV absorption edge moved to the lower wavelength side, causing the bandgap to expand from 3.255 to 3.269 eV. PL spectrum showed that a near band edge UV emission and two broadband peaks detected around 500 nm and 595 nm tend to disappear with Sb doping. [ABSTRACT FROM AUTHOR]

In this work, which aims to investigate the capacitance and conductance properties of ZnCo2O4-doped Gelatin, 5% ZnCo2O4-doped Gelatin film was grown on n-type silicon wafer by sol–gel spin coating with the aim of fabricating Al/ZnCo2O4:Gelatin/n-Si Schottky diode. This investigation also explores the series resistance (R S) and interface state (N ss) characteristics of a diode produced with ZnCo2O4:Gelatin interface layer. Electrical measurements were taken in the voltage range of − 5 V and + 2 V and the frequency range of 30 kHz and 1 MHz. The electrical properties of the diodes were characterized from voltage and frequency-dependent measurements. Capacitance–voltage (C-V) and conductance–voltage (G-V) characteristics yielded higher values showing the significance of the interface states. At lower frequencies, the rise in the capacitance value is signed to the interface state density. The values of N SS for 30 kHz and 1 MHz frequency are 10.5 × 1011 and 4.19 × 1011 eV−1 cm−2. It is recommended to use the produced diode as an electronic device. [ABSTRACT FROM AUTHOR]

A [ZrO2+BTB]C nanocomposite was synthesized and prepared as a thin film using the sol–gel spin coating method. Different characterization techniques for [ZrO2+BTB]C like FTIR, UV–Vis, and optical properties have been used. The resulted XRD and SEM data have been employed to study interface composites. The optimization was performed using DFT by DMol3 and CASTEP program. The chemical structure was confirmed by spectroscopic and structural properties for [ZrO2+BTB]C. XRD results showed the same crystal structure. Combined between experimental and TDD-DFT data, the average crystallite size and composite interface are 12.36 nm and orthorhombic symmetry (a = 7.38(5); b = 18.178(6); c = 26.10(3) Å and a = b = g = 90°) with space group (P61) for [ZrO2+BTB]C, respectively, while those computed by DFT are 2.897 eV and 2.492 eV for as-isolated crystals of [BTB]TF and [ZrO2+BTB]C, respectively. Both [BTB]TF and [ZrO2+BTB]C thin films have direct allowed transitions. In addition, the optoelectrical parameters have been calculated for [BTB]TF and [ZrO2+BTB]C films such as refractive index, extinction coefficient, dielectric constant, and optical conductivity. The simulated values obtained by CATSTEP for the optical parameters of [ZrO2+BTB]C are in good agreement with the experimental values. PL technique analyses indicated two emission peaks appeared at 357 nm, and 497 nm for [ZrO2+BTB]C, whereas three emission peaks appeared at 335 nm, 383 nm, and 477 nm for [BTB]TF. The [ZrO2+BTB]C presents a good candidate for optoelectronics and solar cell applications. [ABSTRACT FROM AUTHOR]

Non-toxic, stable, and earth abundant bismuth is an ideal alternative to poisonous lead in environmentally friendly perovskite solar cell devices. Bi2S3 thin film is a metal chalcogenide, which presents substantial promise because of its optical and electronic properties. In contrast to expensive methods, there are few studies in the literature on n-Bi2S3 thin films prepared using low-cost sol–gel method. Detailed studies on the preparation of Bi2S3 thin film structures by easy, non-toxic and low-cost sol–gel methods have not yet been reported. Therefore, in this study, Bi2S3 thin films were prepared by sol–gel spin coating method. The effects of the thickness and annealing temperature of the films on the film properties are elaborated through crystallinity, morphological and optoelectronic characterizations. The study indicated that both the thickness and the annealing temperature have a great influence on the properties of the films. Thickness-dependent analysis revealed that the films prepared at 650 nm thickness exhibited the best properties; orthorhombic phase polycrystalline structure and n-type conductivity. The room temperature electrical resistivity is in the order of 105 Ω cm. Champion film with optimum crystallinity was achieved by annealing at 350 °C, while the best optoelectronic properties acquired by annealing at 400 °C. The direct optical band gap and crystallite size were 1.5 eV and 18.4 nm, respectively. Additionally, the high-absorption coefficient was in the order of 105 cm−1 state that the suitability of the material for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Electromagnetic signal detection for applications such as astronomy, product quality monitoring, health, and necessitates systems that are very responsive and wavelength selective. High quantum efficiencies and high responsibility have been demonstrated in photodetectors based on Ge–Ga–Sb, primarily in the visible range. The photoelectric responses of new low-voltage, high-responsivity, solution-processed, flexible photodetectors for optoelectronic applications are examined for the first time. This is accomplished by using the melt-quenching procedure to synthesize Ge–Ga–Sb compound and putting it on a silica glass substrate using the spin coating method. The films were investigated in the context of an electrical photodetection sensor based on impedance. Excellent responsivity, particular detectivity, external quantum efficiency, and response time were all demonstrated by the produced device. The findings show that Ge–Ga–Sb has good optoelectronic capabilities and might be used in applications with low optical intensity. [ABSTRACT FROM AUTHOR]

One of the key elements to enhance the performance of solar cells was antireflective surface coatings. It can be employed through different deposition techniques such as spin coating, dip coating, blade coating, etc., In this research work, the coating materials such as ZnO, Ta2O5 and ZnO–Ta2O5 blends were coated over silicon solar cells through electrospraying technique. The performance of coated solar cells were evaluated using different characterization techniques. At the coating time of 90 min and input voltage supply of 17 kV, almost uniform thin films were attained. This was confirmed through FESEM and AFM analysis. The transmittance and power output characteristics of coated glass slides and Si solar cells were examined through UV–Vis spectroscopy and I–V source meter. In comparison with other solar cells, the ZnO–Ta2O5 blend (H3) coated cell exhibit uniform layer deposition and minimal light reflectance of 5%. The maximum power conversion efficiency was achieved for H3 solar cell of 17.7% (direct sunlight) and 19.6% (neodymium light source), due to increased transmittance of photons reaching the depletion region. The electrical resistivity of H3 solar cell was noted as 3.57 × 10−3 Ω cm using four probe method, which was lesser than other solar cells. From the obtained experimental outcomes, ZnO–Ta2O5 blend coated solar cell reveal the maximum performance than other coated and uncoated solar cells. Hence, ZnO–Ta2O5 blends were found to be better antireflective material for attaining maximum output performance of solar cell. [ABSTRACT FROM AUTHOR]

Self-powered visible photosensing and glucose sensing properties of CdS nanorods (NRs) have been investigated. CdS NRs were grown on fluorine-doped tin oxide (FTO)-coated glass substrates using hydrothermal method. Self-powered photodetection of CdS NRs has been studied after spin coating of poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) conducting polymer on the nanorod surface. The device performance has been improved after the treatment of PEDOT-PSS polymer with dimethyl sulfoxide (DMSO) solvent. The maximum responsivity (R λ) of the photodetector has been obtained ~ 11.88A/W at 500 nm wavelength at zero bias. Self-powered glucose sensing has been demonstrated in a photoelectrochemical cell using CdS NRs as photoanodes. The sensitivity towards glucose detection has been obtained 11.24 nA.cm−2. μM−1 under illumination of white LED light. [ABSTRACT FROM AUTHOR]

In this study, structural and magnetic properties of pure and M-doped MoS2 (M: Fe and Cu) thin film were investigated. Two-step film growing process were used to create a thin film which are (i) spin coating and (ii) thermal decomposition. Raman spectroscopy results indicate that two characteristic vibration modes of E 2 g 1 (in-plane) and A 1 g (out-of-plane) 2H MoS2 were observed in all samples. The surface morphology of samples studied by scanning electron microscopy (SEM) images shows that MoS2 crystals formed a back-to-back triangle shape. However, the triangle-shaped grains transform to nanorods when M is doped into the MoS2. Pure and Fe-doped samples show magnetic transition temperatures at ∼247 and 95.5 K, respectively. In constrast, the Cu-doped sample shows strong diamagnetic characteristics in measurements. In addition, the magnetization values increase with the introduction of the Fe atoms into the main structure. According to the magnetic hysteresis curves of samples, pure and Fe-doped samples show ferromagnetic characteristics, while the Cu-doped sample shows weak magnetic characteristics in both 5 and 300 K. [ABSTRACT FROM AUTHOR]

In our study, Al and B co-incorporated ZnO samples were synthesized by spin coating as an alternative to ITO films, which are the favorite of solar cell applications. B element was incorporated to the ZnO film at different rates by keeping the doping ratio of Al element constant. Some features of the produced films were examined using XRD patterns, four-probe technique, atomic force and scanning electron microscopies, UV–vis spectrophotometry, spectroscopic ellipsometry and photoluminescence spectrometry. The Al-B co-doping process has made the optical, surface and electrical features of ZnO film highly suitable for TCO applications, compared to only Al-incorporating process. The resistivity for ZnO film were decreased from 6.12 × 102 Ωcm to 2.07 × 10–4 Ωcm with Al–B co-doping treatment. In addition, Al and B elements caused a significant increase in the transmittance values, surface homogeneity and figure of merit value of the ZnO film. All analyzes proved that Al–B co-incorporated ZnO films can be an alternative to ITO films in TCO applications due to their favorable physical properties. [ABSTRACT FROM AUTHOR]

Pure and doped ZnO thin films with different monovalent elements (Li+, Na+, Ag+ and Cs+) are deposited onto glass substrates using a sol–gel spin coating method. The physical properties of the films are investigated for various ionic radius and concentrations of the dopant. X-ray diffraction results confirm clearly that the synthesized films exhibited hexagonal wurtzite structure without any secondary phases. The Scherer formula reveals that the average size of the crystallites is ranged between 35 and 55 nm. The main finding of this work is to show that the control of the crystalline growth orientation is possible basically by varying the monovalent dopant ionic radius and concentration. This control is therefore considered as a key factor when seeking to promote the ZnO-based transducers. In fact, the ZnO thin films doped by Cs+ (1.67 Å) are preferentially oriented along the c-axis; meanwhile, when decreasing the dopant ionic radius form 1.26 Å (Ag+) to 0.97 Å (Na+), other preferential orientations appear especially (100). However, in the case of Li (0.68 Å), no change in the preferential orientation has been observed until the concentration reaches 10%. Noticing that, the lattice parameters are strongly affected when the ionic radius and/or the dopant concentration change. The SEM micrographs of all the samples exhibit homogeneous and dense grains distribution with a quite smooth surface. UV visible transmittance spectra indicate a high transparency in the visible region with a slight dependence on the dopant radius. The evaluated optical bandgap varies from 3.29 to 3.2 eV. [ABSTRACT FROM AUTHOR]

In this study, the properties of a series of (Sn0.7−xMo0.3 NdxO2+δ) (0.0 ≤ x ≤ 0.3) Nd3+ thin films prepared by sol–gel/spin coating technique were examined. The XRD analysis revealed the formation of all thin films in the form of Cassiterite structure. According to the FTIR investigation, when Nd3+ was substituted for Sn4+ ions in the crystal lattice, the absorption peaks migrated to the lower wavenumber side. This could be related to variations in bond length that occurs when Sn4+ ions in the crystal lattice are replaced with lighter Nd3+ ions. The morphology of the films was examined by using scanning electron microscope (SEM). In terms of Nd content, optical properties such as optical band gap, refractive index (n), and extinction coefficient (k) were investigated. The magnetic characteristics indicated diamagnetic behavior of Sn0.7Mo0.3O2+δ, paramagnetic behavior of Sn0.6Nd0.1Mo0.3O2+δ, and ferromagnetic behavior of samples with a high concentration of Nd, (Sn0.5Nd0.2Mo0.3O2+δ, Sn0.4Nd0.3Mo0.3O2+δ). The presence of active Nd3+ successfully introduced into the Sn:Mo host matrix is confirmed by the excitation dependent (PL) observed in the 350–700 nm range. PL measurements reveal two large bands located at 425 and 466 nm. [ABSTRACT FROM AUTHOR]

In this work, good quality nanocrystalline cadmium sulphide (CdS) thin films were deposited on the suitably cleaned glass slides with different Cu-doping concentrations using the sol–gel spin-coating technique. The effect of Cu doping on the structural, Raman spectra, optical, electrical, photoluminescence, and photoconductivity properties of the fabricated films was studied. The structural properties of the films were investigated using XRD spectra. The X-ray diffraction results indicated that the crystallite size of Cu-doped nanocrystalline CdS thin films was smaller than that of undoped CdS and the cubic zinc blende structure of the films was observed. Raman scattering was utilized to investigate the optical properties of nanocrystalline CdS thin films and reveal the existence of two main peaks 303 and 604 cm−1 which are very close to the standard LO frequency. The optical characterization of the films was carried out from optical transmittance and absorption obtained by a double-beam spectrophotometer in the wavelength range from 400 to 800 nm. UV–visible spectroscopy depicts the enhancement of the optical band gap of Cu-doped nanocrystalline CdS thin films compared to the bulk CdS, as a result of the quantum confinement effect. Photoluminescence spectra of the films reveal the occurrence of blue band emission and an increase in emission intensity with Cu-doping concentration. The change of the electrical resistivity and conductivity of the deposited films with temperature was also investigated. A decrease in resistivity and increase in electrical conductivity was detected as increasing Cu-doping in CdS. The dark and photocurrents and photosensitivity of the films were found to be increased linearly with increasing voltage and doping concentration. [ABSTRACT FROM AUTHOR]

BaMnxTi1-xO3 thin film on a silicon substrate has been prepared through the sol–gel spin coating process. The ferroelectric BaMnxTi1-xO3 film shows the predominant perovskite ABO3 structure for x = 0.2 and 0.3 for the annealing temperature of 650 °C under nitrogen ambient. The metal contact on top and silicon substrate at the bottom of the film forms a Metal-Ferroelectric-Semiconductor capacitor structure. In BaMnxTi1-xO3, the deposited film changes its structural and electrical properties as the concentration value of 'x' is changed. The crystal structure of the deposited film has been analysed by XRD. FESEM, EDS and XPS characterization of the film were carried out to discuss the change in the film structure with the change in the value of 'x'. The Capacitor vs. Voltage (C–V), Current vs. Voltage (I–V), Charge vs. Voltage (Q–V), Endurance, PUND (Positive Up Negative Down) and dielectric study of the films are discussed. Memory window of 8.6 V and leakage current of few nA are obtained. The deposited ferroelectric film shows an endurance of ~ 1011 iteration cycle for the PUND pulse. The optimized doping molar concentration 'x' in BaMnxTi1-xO3 shows favourable results for ferroelectric non-volatile memory application with a low cost fabrication method. [ABSTRACT FROM AUTHOR]

In this work, we report the sol–gel spin-coated novel thin film Aurivillius Phase Layered Bismuth titanate (Bi4Ti3O12, BTO) thin film coated on FTO glass substrate annealed at 700 °C was prepared and its detection of mercury ion. The structural orientation, surface morphology, chemical composition, vibrational, and optical properties of the prepared thin film were characterized using XRD, SEM, XPS, Raman, UV–Vis, and PL, respectively. From the XRD analysis, the crystal growth is well preferred in (117) plane corresponding to the orthorhombic structure of BTO. SEM images of the prepared thin film exhibited an anisotropic plate-like grained structure. Photoluminescence spectra showed a good optical emission peak at 545 nm. In Raman spectra, the observed phonon modes are well correlated to the orthorhombic phase of BTO thin films. XPS confirmed the oxidation states of Bi4Ti3O12 thin film. The electrocatalytic activity of the prepared BTO thin film electrode concerns mercury detection using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) technique. CV analysis disclosed that the prepared thin film electrode is very active in the electrochemical performance of heavy metal (Hg) detection. LSV result reveals that the prepared thin film exhibits enhanced sensitivity and lower detection limit of electrochemical Hg detection. From the electro-oxidation studies, the BTO thin film electrode acts as a favorable candidate for the application of heavy metal detection. [ABSTRACT FROM AUTHOR]

In this work, we report on a highly sensitive carbon dioxide sensor that can operate at low temperatures with rapid detection capabilities. The sensor was fabricated by depositing hydrothermally prepared graphene oxide/cupric oxide nanocomposite onto a glass substrate by a spin coating technique. Morphology, chemical state, and atomic concentration of sensing material were studied by FESEM and XPS analysis. The fabricated sensor shows a remarkable sensing response of 963% for 750 ppm of carbon dioxide gas at an operating temperature of 100 °C. Additionally, the sensor also exhibited a fast response time of 25 s and a short recovery time of 8 s when exposed to different concentrations of carbon dioxide gas from 250 to 750 ppm. Results obtained from the experimental analysis reveals that the p–n heterojunction interface resulting from the decoration of nanostructured CuO over high surface area graphene oxide is responsible for enhanced sensitivity and repeatability of the sensor. [ABSTRACT FROM AUTHOR]

In the present work, we have successfully fabricated undoped and Ni-doped nanocrystalline CdS thin film on an ultrasonically cleaned glass substrate employing the sol–gel spin coating technique. The structural and spectroscopic properties of the films were investigated using XRD spectra, UV–Vis spectroscopy and photoluminescence spectra, respectively. The X-ray diffraction spectra revealed the polycrystalline nature of films with cubic structure and (111) as preferred orientation. The average crystallite size evaluated by the Debye–Scherrer formula lying in the range of 6–12 nm for the deposited films. According to UV–VIS Spectroscopy, the average transmittance of films in the visible region varies between 70–90%. The optical band gap of CdS thin film was evaluated from absorption spectra. The bandgap of the deposited films is in the range of 2.48–2.70 eV which is higher than that of bulk CdS (2.42 eV). This verifies the blue shifting in band edge of CdS nanocrystalline thin films due to the quantum confinement effect. Photoluminescence spectra of the thin film showed that the fundamental band edge emission peak centred at 485 nm also called blue band emission. It is observed that the low temperature resistivity of the films was in the range of 107–103 Ω cm and also found to decrease with increasing Ni concentration, as a result from dc two probe measurements. [ABSTRACT FROM AUTHOR]

Fe-substituted CuO thin films have been prepared by spin coating onto cleaned n-Si and glass substrates at various concentrations (2%, 6%, 10%). The AFM results show that the surface morphology of CuO thin films is strongly influenced by film thickness. The optical band gaps of the films were determined with Kubelka Munk function by using diffuse reflectance data and a reduction of 59 meV in the optical band gap was observed for 10% Fe doped CuO film. The ideality factors and barrier height values of the diodes have been varied between 3.17 and 2.74 and 0.82 and 0.71 eV with the 2%, 6%, and 10% Fe doping, respectively. Additionally, the series resistance (RS) values have been defined via employing the Cheung-Cheung method. The highest and lowest values of RS have been calculated as 1332 Ω for CuO/n-Si and 18 Ω for 6%Fe:CuO/n-Si, respectively. The electrical characteristics of these heterojunction structures have been examined under dark and different illumination intensities. Moreover, their photovoltaic performances have been compared. Furthermore, the power conversion efficiencies of CuO:Fe/n-Si have been calculated and found to be increased from 0.1 to 1.13% with increasing Fe doping. [ABSTRACT FROM AUTHOR]

This paper presents experimental and density functional theory (DFT) investigations of Zn doping role in the Zn@CdO ternary system. Zn doped CdO nanostructures thin films with different Zn concentrations were successfully casted on glass substrates by sol–gel spin coating method. Cubic Zn@CdO structured ternary alloyed nanostructures thin films with 0.0, 1.0, 2.0 and 3.0 wt.% Zn concentrations were obtained. An enhancement in the lateral growth of CdO cauliflower-like nanostructures was observed after Zn addition which leads to a growth of nanostructured films with improved continuity. The effect of Zn doping on the linear optical parameters such as the optical band gap, the absorption index and the refractive index were also investigated. A remarkable blue shift in the band edge was observed as Zn is incorporated into the CdO matrix. In addition, the third order nonlinear optical parameters χ(3) and n2 were calculated and found to be about 2.89 × 10–12–4.33 × 10–14 esu and 2.89 × 10–12–4.33 × 10–14 esu; respectively. A DFT based Wien2k package was utilized to theoretically investigate the lattice parameters, the electronic structure, the absorption index and the refractive index of the Zn@CdO ternary nanoalloys. The role of Zn doping on the aforesaid properties was theoretically investigated for 3.125%, 6.25%, 12.5% and 25% Zn doping concentrations and was compared with the experimentally determined parameters. The combined theoretical and experimental investigations presented herein along with the detailed discussion of the obtained findings would provide a deep understanding of the opto-electronic behavior of the Zn doped CdO nanostructured films as well as their suitability for devices applications. [ABSTRACT FROM AUTHOR]

Thin films of a chlorophyll-like compound methyl-pheophorbide a (Pheo) were prepared from a solution by both spin-coating and drop-casting methods. Despite the fundamental similarity of these two techniques, different self-assembly conditions of Pheo molecules determined the difference in the films morphology. Smoother films without detectable crystallinity were obtained by the spin-coating method, while the drop-cast films featured ordering of molecules and formation of clusters with a size of ~ 1 µm and more. As a result, the films have different photoelectrical properties and, hence, the conditions governing the aggregate growth should be controlled precisely. The Pheo films in any form are good photoconductors: photons from the red and near-infrared domain are the main contributors in the photoinduced current. [ABSTRACT FROM AUTHOR]

The study focuses on to examine the effect of CdS-based electron transport layer on the performance of perovskite solar cell. Based on the novel device architecture, CdS was fabricated using chemical bath deposition at different time interval of 10, 20, and 30 min. However, the perovskite layer was prepared by two-step spin coating technique in order to achieve better structural properties. The analyzed perovskite solar cell shows a very good power conversion efficiency of 11.69%, Jsc 15.4 mA/cm2, Voc of 1.0 V, and FF of 0.75 for the device structure CdS/CH3NH3PbI3/Spiro-OMeTAD for CdS grown for 10 min. Finally, the study discusses on various factors like effect of microstrain, dislocation density, and series resistance on the photovoltaic performance of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Despite the fact that much of the research has been performed on ZnO-based nanoparticles, still a lot of work is unexplored. The synthesis and characterization of the ZnO nanorods have been co-annealed using a simple combustion method and used for gas sensor and photocatalytic degradations applications. Herein pure and In, Sn and Sb tri-dopants were used, i.e. 0.5 at.wt% 1.0 at.wt% and 1.5 at.wt%, while their effects co-annealed on glass substrate at different temperatures at 500 °C and 1100° have been studied. These samples were coated onto the chosen substrate using spin coating technique. Crystallite scale was measured to the range of 30–50 nm. At such temperatures, the grain size measured for the samples was in range of 50–70 nm. This showed that the prepared nanorods are well crystalline and have strong optical properties to handle. Studies of X-ray diffraction showed the influential point (101). These coated samples designed for nitrogen gas sensing have been tested for the development of smart and functional instruments. Furthermore, it was observed that the samples prepared at higher temperatures exhibit better recovery and better reaction time. Valance ion process explains the gas sensors fast reaction and long recovery time. Thus prepared ZnO nanoparticles have photocatalytic degradation (99.86%) only in 55 min. We observed optimum exposure at an operating temperature of 105 °C. It is notable that morphology of susceptible layer nanoparticles is preserved based on different tri-doping concentrations. The concentration of T2-ZnO nanoparticles for photodegradation of the DR-31 dye and NO2 gas sensing applications were 1.0 at.wt% [ABSTRACT FROM AUTHOR]

In this paper, MoO3/MoSe2 nanocomposite was constructed by an improved hydrothermal and spin coating method for fabricating trimethylamine (TMA) gas sensor. The surface morphology and microstructure of the prepared materials were analyzed by XRD, XPS, SEM and TEM characterization methods. The microstructural characterization results demonstrated that the MoO3/MoSe2 nanocomposite had been successfully synthesized, in which the MoSe2 had a flower-shaped structure, and MoO3 had a rod-shaped structure. At the same time, the MoSe2 surface exhibited periodic honeycomb structure. The gas sensitivity experimental results showed that the proposed MoO3/MoSe2 sensor had excellent TMA sensing performance at room temperature, including high response capability, low detection limit (20 ppb), short response/recovery time (12 s/19 s), long-term stability, good repeatability and outstanding selectivity. The heterostructure of MoO3/MoSe2 had made outstanding contributions to the enhanced TMA gas sensing performance at room temperature. [ABSTRACT FROM AUTHOR]

4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based BOD-Pyr compound was synthesized according to the literature and HOMO and LUMO energies of the BOD-Pyr were calculated by DFT/B3LYP/6-311G(d,p) method using on Gaussian 09 W. Au/BOD-Pyr/n-Si/In Schottky diode were fabricated using thermal evaporation and spin coating technique. The electronic and photovoltaic properties of Au/BOD-Pyr/n-Si/In diode have been investigated by current-voltage (I-V) measurements at dark and under various illumination intensities. The calculated ideality factor and barrier height of the diode in dark were found to be 2.84 and 0.75 eV, respectively. These parameters were also obtained under 100 mW/cm2 illumination level as 1.55 and 0.87 eV, respectively. The values of open-circuit voltage and short circuit current density were obtained as 0.26 V and 0.56 mA/cm2 under the illumination level of 100 mW/cm2. These all findings suggest that Au/BOD-Pyr/n-Si/In diode can be used as photodiode in optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this work, the impact of UV illumination intensity on a self-powered photodiode based on organic NPD:Alq3 composite is comprehensively investigated. Solution-processed spin coating was used to fabricate the active layers followed by electrode deposition to form devices with architecture ITO/PEDOT:PSS/NPD:Alq3/LiF/Al. UV–Vis and PL spectrometers were used to investigate the properties of the active layer, while a Keithley source meter was utilized to record the current–voltage response of the photodiodes. Results showed that the self-powered photocurrent was linearly increased (with logarithmic gradient ~ 0.5, confirming the presence of a bimolecular recombination), while the photovoltage was logarithmically increased with illumination intensity. A sensitivity of 1.3 × 105 was achieved with responsivity and detectivity of 5.39 mA/W and 5.25 × 1011 Jones, respectively at 40 mW/cm2 illumination. The photodiode sensitivity was found to be linearly increased, while the responsivity and detectivity were exponentially decreased with illumination intensity. The variation of bulk resistance of the photodiode followed an exponential and linear relation under low and high illumination intensities, respectively. [ABSTRACT FROM AUTHOR]

The development of 3D-printed sensors and actuators from piezocomposite materials has increased in recent years due to the ease of production, low-cost and improved functionality additive manufacturing provides. The piezocomposite material developed in this work has the potential to be used as a functional material in stereolithographic additive manufacturing by combining the optical, viscoelastic properties of NOA 65 and the piezoelectric properties of Barium Titanate. The new (0–3) piezocomposite material consists of Norland Optical Adhesive 65 (NOA 65) as the polymer matrix and Barium Titanate (BaTiO3) with particles sizes (100 nm, 200 nm and 500 nm) as the dielectric filler. We synthesized thin film samples of the (0–3) piezocomposite with 60% w/w BaTiO3 using solution mixing and spin coating method to produce samples with layer thickness of 100 µm. Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) techniques were used to analyze the microstructure of the piezocomposite to determine the effect of different particles sizes of BaTiO3 on the structural and mechanical properties of the composite. The longitudinal piezoelectric coefficient d33 was also measured using the laser vibrometer technique. Both single point scans and full surface scans were carried out to obtain the average piezoelectric coefficient d33 of the composite material. The results of the SEM confirmed the (0–3) structure of the piezocomposite material with isolated BaTiO3 nanoparticles. It further showed the uniform distribution of the BaTiO3 nanoparticles across each of the samples. FTIR analysis showed that the filler nanoparticles had no effect on the native structure of the polymer matrix. The longitudinal piezoelectric coefficient d33 of the piezocomposite material was observed to increase with increasing BaTiO3 particle sizes, while the indentation modulus of the composite investigated using the method of Oliver and Pharr was observed to decrease with an increase in particle size. Results from the single point scans showed the composite with BaTiO3 particle size 100 nm, 200 nm and 500 nm having an average d33 of 2.1 pm/V, 3.0 pm/V and 3.9 pm/V while the average d33 obtained from the full surface scan of 1430 scan points showed 1.4 pm/V, 6.1 pm/V, 7.2 pm/V. [ABSTRACT FROM AUTHOR]

A new nanocomposites series of polypyrrole/reduced graphene oxide (PPy/rGO) and polypyrrole/reduced graphene oxide covalently bonded with aryl 4-carboxybenzene diazonium salt (PPy/rGO-aryl-COOH) were prepared by simple one-step chemical oxidative synthesis. Spin coating technique was used to deposit the as-prepared nanocomposites on BOPET substrate for testing their chemiresistive sensitivity properties towards online detection of (NO2) vapors at ambient temperature. The recorded morphological and structural data confirmed that PPy/rGO-aryl-COOH forms a homogeneous nanocomposite within the size of 80 nm and improvement of the crystalline ordering. PPy/rGO-aryl-COOH revealed the optimal NO2 sensing properties in terms of higher sensitivity (1.01%/ppm), faster response time (129 s), detection limit of (2 ppm), and reproducibility. Moreover, stability was tested under humidity and temperature effects. Finally, impedance spectroscopy is conducted in the fresh air and in the presence of gas. These results highlight the paramount role of functionalization of reduced graphene oxide (rGO-aryl-COOH) in improving both the sensitivity and the reactivity of our produced nanocomposite regarding NO2. Strong interaction between the NO2 gas molecules and the aryl-COOH-functionalized rGO has dramatically enhanced the electronic properties of these nanocomposites. These striking characteristics of the newly developed nanocomposites make them very suitable for NO2 gas sensing. [ABSTRACT FROM AUTHOR]

The formation of a boron-rich layer (BRL) is a common phenomenon during the fabrication of boron (B) emitter due to different solubility of B in the silicon oxide layer and the silicon substrate. In our work, we employ alumina oxide (Al2O3) layers as reaction barriers to avoid the production of the silicon oxide layer and eliminate the BRL. The B diffusion in silicon becomes much more accessible that the diffusion concentration and depth are increased dramatically with the absence of BRL. The Al2O3 layer can also improve the uniformity of surface sheet resistance due to its hydrophilic, bringing superior quality of liquid boron source spin coating. We investigate the influence of Al2O3 with different thicknesses and refractive indexes on the B diffusion. The diffusion profiles of B in the silicon capped with Al2O3 become broader as the thicknesses and refractive indexes of Al2O3 increase. Besides, iron is employed as a model impurity to study the gettering effects during the B diffusion. The increase of the maximum B concentration and the total amount of B doping contribute to a superior gettering effect with the interstitial iron concentration decrease from 3.91e12 cm−3 to a minimal value of 1.65e11 cm−3, and the iron concentration even dropped to 7.24e10 cm−3 after attaching a second deposition. We analyze the mechanisms of gettering systematically during the B diffusion. The present work will help deepen the understanding of B doping and the fabrication of B emitter. [ABSTRACT FROM AUTHOR]

In the past few years, there has been a significant demand for the development of high dielectric constant polymer composites for flexible electronic applications. However, the development of these flexible and stretchable dielectrics through simple and economical processing methods still remains challenging. In the present work, we have addressed this problem by developing high dielectric constant, flexible, calcium copper titanate (CCTO)/ thermoplastic polyurethane (TPU) composites through a simple and cost-effective casting method. At room temperature, 40 vol% CCTO/TPU composite exhibited a dielectric constant of 56 (1 kHz) along with an elongation at break of 202%, making it a promising dielectric material for flexible electronics. To our knowledge this is the best among the reported works in ceramic/ polyurethane composites, exhibiting a remarkable combination of high dielectric constant, excellent elongation at break and good mechanical strength. A prototype embedded capacitor was fabricated on copper cladded printed circuit board (PCB) by spin coating and a specific capacitance of 1.05 nF/cm2 was achieved at 1 kHz. [ABSTRACT FROM AUTHOR]

Al/n-Si/Ti1−xO2CdxO/Al photodiodes were produced using sol–gel and spin coating methods where CdO dopant was applied on different concentrations (x = 0.0; x = 0.01; x = 0.05; x = 0.10). Cd dopant effect upon structural, optical, photodiode and electrical properties was assessed. Scanning electron microscope and energy-dispersive spectra were used in the structural investigation. Optic properties were assessed using UV–Vis spectroscopy and bandgap energies of the photodiodes were calculated which were found to be between 3.25 and 3.36 eV. Increased bandgap energy was observed with increased CdO doping rate. Photodiode properties were assessed under varying daylight illuminations. Barrier height, ideality factor, dark current, linear dynamic rate, photosensitivity, photoresponsivity of the photodiodes were calculated. Electrical properties of the Al/n-Si/Ti1−xO2CdxO/Al photodiodes were calculated where conductance–voltage and capacitance–voltage plots were obtained. Corrective conductance–voltage and corrective capacitance–voltage graphs confirm that the electrical properties of the photodiodes depend on AC signal frequency. Frequency-dependent electrical characteristics were attributed to the density of interface states which were found to be between 1011 and 1012. Decreased density of interface state was found for increased AC signal frequency. [ABSTRACT FROM AUTHOR]

The enhanced saturation magnetization in Mn-doped ZnO (ZnO:Mn) films by Amine functionalization has been reported here. First, Mn (5 mol%, 10 mol%, and 15 mol%)-doped ZnO thin films were grown by radio-frequency (RF) magnetron sputtering which are further functionalized using trioctylamine (Amine) by spin coating. XRD pattern confirms the (002) plane of hexagonal wurtzite structure and showed that there is no significant change in the peak position after Amine functionalization. The presence of green band (GB) emission at 2.4 eV and blue band (BB) at 2.8 eV by photoluminescence study confirms the existence of oxygen vacancies in the film. Further, after Amine functionalization, quenching of green band and blue band emissions were observed. The presence of elements in the films, in particular, organic ligand, N was confirmed by XPS analysis. The VSM measurement confirms that all the grown ZnO:Mn films exhibit ferromagnetic behavior. Further, the Amine functionalization enhances the saturation magnetization (Ms) due to hybridization between 4s and 2p orbital which actually makes Zn–N and N–O bonds and induces the magnetization in the system. [ABSTRACT FROM AUTHOR]

A low cost, non-vacuum process involving spin coating of metallic precursors followed by selenization was substantiated for the fabrication of CIGS (CuInxGa(1−x)Se2) thin film absorber. Spin coating of CIG precursors using environmentally benign solvents and studying the effects of various heat treatments on the spin-coated CIG precursor film leads to high-quality crystalline CIGS thin films with minimum carbon impurities. In this work, effects of various heat treatments of CIG precursor (heat treatment of precursor films after each individual run of spin coating using hot plate, using air dryer, without any pre-heat treatment and heating of 30-run coated sample on hot plate for 30 mins) followed by selenization has been investigated and being reported. The as-prepared CIGS thin film samples are characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), Field emission scanning electron microscopy (FESEM), UV-Vis-IR spectroscopy and X-ray photo electron spectroscopy. From XRD pattern and Raman spectra, MoSe2 phase is also observed along with tetragonal chalcopyrite CIGS phase. Through FESEM and EDS, it is observed that heating each individual run has resulted a high-quality compact dense film with minimum carbon composition. XPS also confirms the minimum carbon composition in case of preheating individual run. From UV-Vis spectra, the bandgap of the prepared CIGS material is found to be 1.5 eV, essential for the cell fabrication. [ABSTRACT FROM AUTHOR]

The spin coating method was employed to fabricate Yb-doped ZnO thin films at 0, 3, 5, 7, and 9 at.% over a glass substrate at low temperature. X-ray diffraction analysis revealed that the hexagonal wurtzite structure was retained even at high doping contents. With the incorporation of Yb+3 ions, a slight decrease in the lattice parameters and crystallite size was observed as the ytterbium content increased. X-ray photoelectron spectroscopy confirmed the presence of ytterbium in the doped ZnO films, and the oxidation state of ytterbium was 3+ for all the samples. Morphological studies revealed a surface microstructure formed by micro islands, which tended to be denser as the ytterbium content increased. Optical transmittance was observed at approximately 75–85%, a blueshift was observed, and consequently, an increase in the bandgap, which varies from 3.0 to 3.2 eV, was observed. The refractive index and extinction coefficient decreased as the ytterbium dopant concentration increased. The photoluminescence results exhibited a strong ultraviolet emission, allowing the use of these thin films in optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this study, synthesized strontium titanate (SrTiO3) nanocubes were coated on n-Si semiconductor by spin coating to obtain a heterojunction device. Transmission electron microscopy image, scanning electron microscope image and x-ray diffraction patterns of thin film of SrTiO3 nanocubes coated on Si surface were taken for structural and morphological characterization of the material. The basic device parameters such as ideality factor (n) and barrier height (Φb) values of the reference Ni/Si/Al metal–semiconductor diode and of the Ni/SrTiO3/n-Si/Al heterojunction devices were calculated with the thermionic emission (TE) theory. The n and Φb values of the reference Ni/n-Si/Al device were calculated as 1.93 and 0.60 eV, respectively at room temperature. On the other hand, lower n and higher Φb values of Ni/SrTiO3/n-Si/Al heterojunction device were calculated as 1.34 and 0.63 eV, respectively. With these results, the current–voltage (I–V) measurements of the heterojunction device in the 80–400 K range were taken and the n,Φb, series resistance (Rs) values were calculated depending on the temperature by using different methods such as TE, Cheung and Norde functions. It was observed that while the temperature values decreased, n and Rs values of the device increase and Φb value decreases. The results obtained showed that the charge transport system is compatible with TE. The device parameters calculated from the Cheung and Norde methods also showed similar changes depending on the temperature. However, since the calculation method is different according to the TE method, different values were obtained in the device parameters. In addition, the curve Φb and (1/n)−1 against (1/2kT) was observed in accordance with the double Gauss distribution of the barrier heights. It was seen that the reverse bias I–V characteristics of the Ni/SrTiO3/n-Si/Al can be used in thermal sensors applications. [ABSTRACT FROM AUTHOR]

Hafnium oxide (HfO2) thin films were formed by spin coating deposition and annealed in ambient air. Following the molarity optimization of hafnium content in the solution, effect of spin coating and thermal processes on the antireflection properties were analyzed. Characterizations were carried out by spectrophotometer, X-ray diffraction, spectroscopic ellipsometer and scanning electron microscopy measurements. Post deposition annealing temperatures range from 500 to 1000 °C. Annealing led the crystallinity of the films above 500 °C and possess monoclinic phase. Average reflectivity of 11.32% was achieved with 71.36 nm HfO2 film after annealing at 700 °C. Ellipsometer measurements reveals refractive index of such a film as 1.934 at 600 nm. Average reflectance increases when annealing temperature is over 700 °C mainly due to the increase of refractive index which is recorded as 2.05 after annealing at 800 °C. Fresnel equations, transfer matrix method and PC1D simulations were carried out for reflectance spectra approximations. The experimental results and the theoretical data were relatively comparable. Spin coating HfO2 thin films are found promising as an antireflection layer for solar cells. [ABSTRACT FROM AUTHOR]

In the current study, thin films of tin sulfide (SnS) were grown by sol–gel spin-coating technique deposited on glass substrates. The obtained thin films were characterized using X-ray diffraction (XRD), photoluminescence (PL) and UV–Vis spectrometer and the four point technique, respectively. The effect of annealing temperature on the SnS properties has been studied. The XRD results reveal that the films annealed at 500 °C have good crystalline quality with orthorhombic phase. Fourier-transform infrared spectroscopy (FTIR) spectra shows the Sn–S bond. The photoluminescence spectra showed two categories of band emission. The optical parameters (α, ε, n, k, Eg, and σop) were determined using UV–Vis spectroscopy. Moreover, the obtained results were compared to the theatricals results obtained with density functional theory (DFT) method using ab-initio approach. The optical and the electrical properties of the SnS Layers annealed at 400 °C and 500 °C offer the best possibility for their utilization in photovoltaic applications. [ABSTRACT FROM AUTHOR]

This work demonstrates a route to making mixed halide perovskite powders at room temperature by the anti-solvent-assisted crystallization method. Although, mixed halide CH3NH3PbBr3−xClx perovskites have been prepared by different methods, however, to the best of our knowledge the anti-solvent-assisted crystallization method is employed here for the first time to prepare mixed halide CH3NH3PbBr3−xClx perovskite powders. Solution-processed methyl ammonium lead tribromide CH3NH3PbBr3 (x = 0) and different amounts of chloride (Cl) containing mixed halide perovskites (CH3NH3PbBr3−xClx) were prepared for compositions of x = 0.5, 1, 1.25, 1.75. It reveals that bulk CH3NH3PbBr3−xClx samples are highly crystalline and exists in pure single cubic phase with an increased tolerance factor as compared to pure CH3NH3PbBr3. The CH3NH3PbBr3 perovskite has space-group Pm-3 m and a cell parameter of 5.930 Å (volume = 206 Å). The synthesis route adopted here gives access to hybrid perovskites powders with high Cl content and hence enables the band gap to be precisely tuned over a range from 2.26 to 2.49 eV. The powder samples display the subtle shifts in the emission spectra and the photoluminescence kinetics exhibits a decrease in average lifetime by increasing the Cl contents due to the presence of trap states in the structures that encourage non-radiative recombination of charge carrier. Conventionally, the CH3NH3PbBr3-based inverted solar cell architecture is prepared via mixing of the CH3NH3Br and PbBr2 precursors. In contrast, herein, the precursor solutions are directly prepared from the CH3NH3PbBr3 powder and the active layer of the inverted perovskite solar cells are then spin coated using this solution. The high Voc value of the fabricated solar cells potentially makes it a promising candidate for tandem photovoltaic, photocatalytic water splitting, and semi-transparent photovoltaic applications. [ABSTRACT FROM AUTHOR]

Resistive switching effect based on graphene-embedded poly(4-vinyl phenol) composite film by spinning coating have been investigated. The nonvolatile WORM characteristics were researched. The influence of the increasing content of graphene on the resistive switching characteristics is mainly manifested in the increase of current in high resistance state, the decrease of the threshold voltage and the decrease of the ON/OFF ratio. The nonvolatile WORM characteristics of graphene poly(4-vinyl phenol) composite thin films could be ascribed to continuous conductive pathways caused by the graphene during spin-coating of the poly(4-vinyl phenol) composites on ITO substrates. [ABSTRACT FROM AUTHOR]

Two-step sequential spin coating deposition technique provides a cost-effective and high performance route for the synthesis of the organometallic lead halide perovskite materials. In this method, initially the metal halide film is coated, over which the MAI with a particular concentration is again spin-coated. However, it is difficult to obtain complete conversion of PbI2 in CH3NH3PbI3 perovskite. In this work, we show that good quality perovskite films can be coated by a three-step method to obtain improved conversion to perovskite and with improved materials properties. We have coated the perovskite films by two-step as well as three-step methods and presented a comparison of obtained film properties. Our results show that at lower concentration of MAI, complete conversion of PbI2 does not take place. With increase in MAI concentration, in addition to the perovskite phase an intercalated MAI into PbI2 phase is formed. In three-step coating, good phase of perovskite and improved morphology is obtained at comparatively lower MAI concentration. At higher concentrations of MAI in three-step method, leads to removal of already existing perovskite material and therefore leads to lower absorption. [ABSTRACT FROM AUTHOR]

The synthesis of ZnO/CuO films on ITO substrate was realized in two steps, first ZnO was deposited electrochemically and then CuO nanoparticles were precipitated with help of spin coating technique. ZnO nanorods were obtained in aqueous Zn(NO3)2 solution, in presence of KCl as capping agent. Spin coating technique yielded CuO nanoparticles on these nanorods, particle size was employed by copper (II) acetate and ethanolamine in 2-methoxyethanol. In addition, field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy studies were also realized for understanding the structure. UV–Visible spectrophotometer study results revealed that the bandgap value of bilayered structure was governed by presence of CuO nanoparticles. Mott–Schottky analysis was realized for characterization of prepared semiconductor materials, which indicated to + 0.571 for ZnO/CuO(3), while these values were + 0.532 V and − 0.360 V for CuO and ZnO, respectively. Electrochemical measurements were realized with help of solar simulator, for testing photocatalytic activity of ZnO/CuO as photocathode material, in aqueous solution. [ABSTRACT FROM AUTHOR]

We have investigated the dependency of hysteresis in all-ambient-processed perovskite solar cells on the solvent used for the synthesization of perovskite. Methylammonium lead iodide (MAI) perovskite solar cells have been fabricated using the two-step sequential spin coating method. The influences of PbI2 precursor on the cell performance and its hysteresis are investigated using four different solvents of pure dimethylformamide (DMF), pure dimethyl sulfoxide (DMSO) and mixtures of DMF:DMSO with the ratios of (4:1) and (1:4). The results indicate that a small amount of DMSO in DMF leads to produce large grains of perovskite with proper coverages at the interfaces with hole and electron transport layers. The best conversion efficiency of 10.9% was obtained for the cell prepared by the solvent of (4:1) for DMF:DMSO. The best hysteresis was also obtained from the same cell with the hysteresis index of 0.009. [ABSTRACT FROM AUTHOR]

The effect of annealing temperature on the structural, morphological, optical, magnetic and electrochemical properties of spin coated NiO thin films were studied. The XRD analysis shows that all the annealed NiO thin films are cubic structure with (200) preferred orientation. The XPS spectrum indicates that the main peak and satellite peaks of Ni (2P) and O (1S) show the presence of Ni2+ cation and O2− anions. Raman spectra show (1P) 1LO and (2P) 2LO modes for annealed NiO thin films. The SEM result shows that, increase in annealing temperature increases the grain size. UV–Visible spectrum exhibits high transmittance for annealed NiO thin films. The band gap energy decreases from 3.72 to 2.89 eV with increasing annealing temperature. The room temperature PL spectrum of NiO thin film has blue and violet emission in addition to UV emission. VSM studies revealed that a weak ferromagnetic behavior has shown by films annealed upto 400 °C and thereafter the magnetic behavior changes to paramagnetic nature. The NiO thin film annealed at 600 °C shows high specific capacitance by cyclic voltammetry analysis. Equivalent series resistance of NiO thin films were measured using electrochemical impedance spectrum and it decreases with increasing annealing temperature. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth performance-based comparison of organic field-effect transistors (OFETs) prepared using the conventional spin coating (SC) technique and a recently developed floating film transfer method (FTM). A remarkable improvement in the performance of transistors fabricated using FTM was achieved in comparison to their SC counterparts. The estimated value of width-normalized contact resistance in FTM-based OFETs was an order lower in comparison to that of transistors prepared using SC technique. The observed results were credited to a significant enhancement in the length of π-conjugation due to the presence of edge-on oriented polymer chains of active layer deposited using FTM, leading to the lowering of carrier injection barrier at the Au/P3HT interface. These results were well supported through absorption, photoluminescence and Raman measurements as well as the anisotropy measurements using polarized absorption spectra, which also pointed towards the improvement in the polymer chain alignment of thin films prepared by FTM over that prepared by the conventional SC technique. The results indicate thin film morphology as a key towards reducing the contact resistance in OFETs. [ABSTRACT FROM AUTHOR]

In this research work, the photocatalytic degradation methyl orange (MO) was carried out using Al2O3-NP/InSnO2 nanocomposite under UV illumination. The Al2O3-NP electrode was successfully formed by a two-step anodization method and Al2O3-NP/InSnO2 electrode was obtained via the sol–gel spin coating method. The structural properties of the samples have been characterized by a series of techniques, including field-emission scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and the contact angle and surface energy measurements. The influence of variables such as initial MO concentration, initial pH value, temperature, and reusability was researched. The kinetics of the photocatalytic degradation of MO can be best described by the pseudo-first-order model. Moreover, the activation energy (Ea), change of enthalpy (ΔH), free energy (ΔG), and entropy (ΔS) are evaluated. The activation energy has been found at 20.89 kJ/mol. The results indicated that the Al2O3-NP/InSnO2 photocatalyst has an excellent activity for photocatalytic degradation in the treatment of wastewater. [ABSTRACT FROM AUTHOR]

In this study, semiconductor device applications of organic material sunset yellow (SY) (C16H10N2Na2O7S2) has been investigated. The SY thin film was grown on n-Si via spin coating method and the Au/SY/n-Si/Au heterojunction was fabricated. The basic diode parameters of device were determined by the current–voltage (I–V) and capacitance–voltage (C–V) measurements at the room temperature. The values of the ideality factory (n) and barrier height (Φb) were evaluated as 1.15 and 0.70 eV, respectively; and series resistance (Rs) of device was found using Norde functions. The values of built in potential, donor concentration, Fermi energy level and barrier height were also estimated from the linear C−2–V curves with reverse bias room temperature and difference frequency. Furthermore, I–V measurements were applied under different illuminations; some photoelectrical parameters of device were evaluated to understand the photo response properties of the device. Consequently, the results confirmed that the barrier height can be modified by interfacial SY layer, and the device can be used in optoelectronic applications such as optical sensor or photodiode. [ABSTRACT FROM AUTHOR]

This study is aimed at obtaining a relatively higher-color-rendering index (CRI) white LED using a blue-emitting Sr4Al14O25:Eu2+ phosphor that could smooth out LED flicker. In order to study the luminescence of the phosphors in the LED package, a thin Sr4Al14O25:Eu2+ film and three-phosphors-containing (green YAG:Ce3+, red CASN:Eu2+, and indigo Sr4Al14O25:Eu2+) film were prepared using a spin coating method. Meanwhile, three-phosphors-LED package was fabricated using a dispensing process, whereby the chip surface was automatically leveled to form a film with the same composition and components as that of the three-phosphors-containing film. In order to study the reliability of Sr4Al14O25:Eu2+ phosphors in the resin, high-temperature and high-humidity test, Xenon lamp aging test, and thermal cycling test were carried out. The Sr4Al14O25:Eu2+ phosphors in the resin were also characterized through photoluminescence (PL) and PL decay curve analyses. The electroluminescence, correlated color temperature, and temperature-dependent PL of the three-phosphors-containing film were measured using an integrating sphere. The three-phosphors-containing film displayed high reliability and thermal stability. The blue LED was coated with a three-phosphors-containing film, which led to a correlated color temperature of ~ 4500 K and a high CRI (Ra > 90.2).This LED package had an afterglow light that could eliminate the observed LED flicker. [ABSTRACT FROM AUTHOR]