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Chemical vapor deposition (CVD), a low-cost and a scalable deposition technique, allows the growth of methylammonium lead iodide (MAPbI3) films without the use of solvents, substantially increasing air stability while also inducing the stable cubic phase at room temperature and at pressures as low as 0.25 GPa. MAPbI3 thin films were grown by a facile two-step low-pressure vapor deposition process in a single reactor. This method results in films, which are usually in the tetragonal phase (space group: I4/mcm) and occasionally in the cubic phase under ambient conditions. High-pressure synchrotron-based X-ray diffraction studies from CVD-grown MAPbI3 crystallites show that the sample remains in the cubic phase (space group: Im $$\bar{3}$$ ) between 0.25 and 3.0 GPa. Temperature-dependent transport measurements show sharp anomalies, correlating with the structural changes. The transport measurements from the CVD-grown cubic MAPI3 film is further compared with a film in the tetragonal phase.

Mixed halide perovskites with chlorine (Cl) content have received significant interest due to better charge transport properties and longer diffusion length compared to pure iodine-based perovskites. The superior properties of Cl-doped perovskites improve solar cell device performance, although the quantification of Cl composition in the perovskite films remain difficult to achieve. Hence, it is difficult to correlate the Cl-quantity with the improved device performance. In this work, we deposited Cl-doped perovskite films through a facile three- and two-step sequential chemical vapor deposition (CVD) where lead halide films were deposited in the first steps of the process and subsequently converted to perovskites. No Cl substitution by iodine was observed during a sequential deposition of lead chloride and lead iodide films which reacted to form a lead chloride iodide phase (PbICl). The substitution of Cl by iodine ions only occurred during the conversion to perovskite phase. Large perovskite grains (greater than 2 µm) were realized when converting a PbI2 film to perovskite compared to chlorine containing lead halide films, contradicting literature. However, Cl doped perovskite solar cells showed improved device efficiencies as high as 10.87% compared to an un-doped perovskite solar cell (8.76%).

Energy filtered transmission electron microscope imaging gives direct evidence of the nano-void network within hydrogenated nano-crystalline silicon thin films, deposited by reducing the hydrogen dilution as a function of deposition time (so called hydrogen profiling) during hot-wire chemical vapor deposition. Electron thickness maps show a t/λ value of approximately 0.38 in the void-rich areas compared to 0.47 in the continuous film, where t is the depth through which the electron beam is scattered and λ the electron mean free path in the Si thin film. Three-window elemental mapping shows no oxygen diffusion throughout the film architecture, whereas spectral imaging in combination with scanning transmission electron microscopy-coupled energy loss near edge fine-structure analyses along the growth direction of the film, across the tip and along the grain boundaries of the conically shaped crystals reveal changes in the Si-L3,2 and L1 energy-loss edges. In particular, the amorphous tissue between cone tips in the incubation layer typically shows a poorly defined L2 ionization edge, which progressively becomes more pronounced in the crystalline areas. Subtle variations in the L1 lineshape along the length of the film, characteristic of hydrogen passivation, confirm the profiling during synthesis.

The Steel/Ni reinforced with 1.0–1.5 wt% TiC composite material was developed by compaction and sintering processes. Optical microscopy and Zeiss-Auriga field-emission scanning electron microscope (FE-SEM) revealed that the TiC particles segregated around the spherical Steel/Ni grains. Moreover, the 1.0 wt% TiC- Steel/Ni composite has the FCC Steel/Ni matrix while the 1.5 wt% TiC- Steel/Ni composite is comprised of the BCC Steel/Ni phase. The large TiC grains were found mostly on the 1.0 wt% TiC- Steel/Ni composite. Additionally, the 1.5 wt% TiC-Steel/Ni composite was composed of the ultrafine TiC grains that surrounded the FeNi spherical grains. The FCC Steel/Ni (1.0 wt% TiC)) composite has lower average hardness compared to the B2 Steel/Ni (1.5 wt% TiC) phase.

There is a pressing need for the development of nanoparticles (NPs) for environmental nanoscience and nanotechnology. Bio-inspired synthesis of lead oxide nanoparticles has been successfully demonstrated using an aqueous extract of Rosmarinus officinalis (rosemary) leaves. Structural and optical investigations of lead oxide annealed at 600 °C were carried-out using complementary techniques namely, X-ray diffraction (XRD) that showed the formation of both form α-PbO (tetragonal) and β-PbO (orthorhombic) NPs with the average crystalline size found approximately at 8.96 nm whereas field emission scanning electron microscopy (FESEM) revealed NPs highly agglomerated with the average particle size found to peak at 12.69 ± 0.27 nm. Energy dispersive X-ray spectroscopy (EDS) confirmed the high purity of PbO as well as attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy. From UV–Vis-NIR, the energy bandgap has amounted to 4.44 eV and the photoluminescence (PL) emission spectrum showed broad nature of visible emissions peaks at 361, 448, 562 and 689 nm with high surface defects and oxygen vacancies. Through these findings, the use of Rosemary leaves extract is hereby shown to be a cost-effective and environmentally benign alternative to synthesize lead oxide nanoparticles (PbO NPs).

Green synthesis of nanoparticles represents an important part of nanotechnology that offers outstanding eco-friendly and financial benefits when compared to conventional methods that use toxic substances and involve complex processes. In this paper, we report a completely green process in which aqueous extract of rosemary leaves containing bioactive molecular compounds (flavonoids, monoterpenoids, phenolic acids, and diterpenoids) acted as both chelating and stabilizing agents to facilitate the synthesis of NiO NPs. Apart from the nickel metal precursor, the synthesis was free of solvents and surfactants in this method to adhere to green chemistry principles and the impartation of environmental benignity. To achieve the aim of the study, structural and optical property analyses of Bunsenite annealed at 500 °C were carried-out using complementary techniques namely high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and UV–Vis-NIR absorption spectroscopy. HRTEM micrographs revealed the self-assembled, highly agglomerated quasi-spherical shaped NPs with a cubic structure and the average size was found to peak at 8.09 ± 0.20 nm. SAED and XRD exhibited the polycrystallinity and the purity of NiO NPs and the average size was found in the range of 11.598–15.527 nm. Besides, EDS depicted the presence of Ni and O in the sample while ATR-FTIR illustrated the Ni-O chemical bonds. From UV–Vis-NIR, the optical band gap amounted to 3.39 eV confirmed the formation of NiO NPs. Thereby, an easy and effective green approach for the synthesis of Bunsenite with efficient properties is reported.

Transparent metal oxide thin films were synthesized on indium tin oxide (ITO) substrates via the sol-gel spin coating method using various precursor solutions. The types of metal oxides investigated were zinc oxide (ZnO), titanium dioxide (TiO2) and molybdenum oxide (MoOx) whose purpose was to serve as buffer layers in organic solar cells. ZnO and TiO2 layers were to serve as electron transport layers (ETL), and the MoOx layer served as a hole transport layer (HTL). Compared to conventional ordering, in this set-up, the sequence of the buffer layers is inverted to improve the stability of the polymer solar cells. The annealing temperature during the preparation of the ETL metal oxide layers was varied in order to investigate the effect on the morphological properties of the thin films. The HTL layer was both spin-coated and thermally evaporated and the results were compared. The surface morphology and elemental analysis of the prepared samples were studied using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) capability. The optical properties were investigated by UV–Vis spectroscopy and it was found that the metal oxide layers have high optical transparency in the visible range, as required. The crystal structures of the prepared metal oxides were investigated by X-ray diffraction (XRD). A comparative study on the effect of the ETLs individually in solar cells was done by incorporating them individually with active layers of blends of poly (3-hexylthiophene) (P3HT), as electron donor and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as electron acceptor respectively. The device performance was subsequently measured and compared.

Biosynthesized hematite phase α-Fe2O3 nanoparticles (NPs) have been successfully demonstrated via an entirely green process mediated aqueous extract of Rosmarinus officinalis (rosemary) leaves acting as both stabilizing and capping agents. The synthesis was free of solvents and surfactants to adhere to green chemistry principles and the impartation of environmental benignity. To achieve the goal of this study, the main physical properties of the biosynthesized α-Fe2O3 NPs were carried-out using complementary techniques namely, field emission scanning electron microscopy (FESEM) which revealed the self-assembled, highly agglomerated NPs, and the average size was found to peak at 6.531 ± 0.148 nm while X-ray diffraction (XRD) exhibited several Bragg diffraction peaks in line with the rhombohedral structure and the crystallinity nature of α-Fe2O3 NPs with an average size within the range of 7.412–10.742 nm in agreement with the FESEM results. The energy-dispersive X-ray spectroscopy (EDS) elucidated the presence of Fe and O in addition to contaminating elements from the natural extract while attenuated total reflectance-Fourier transform infrared (ATR-FTIR) depicted Fe-O chemical bonds. Besides, the photoluminescence (PL) emission spectrum indicated the existence of surface defects and oxygen vacancies.

Photoactive hybrid layers of material combinations such as region-regular poly (3-hexylthiophene), i.e. rr-P3HT and silicon nanowires (SiNWs) have been extensively studies over the past decades. However, these hybrid layers still require further exploration as candidates for solar cell fabrications due to the scarcity of fundamental understanding of the mechanisms that govern the charges migration within layers, which might be limiting the full potential of these materials. In this study, we synthesised SiNWs via metal assisted chemical etching (MACE) and incorporated different weight ratios of as-synthesised wires with rr-P3HT, in blended form to fabricate solar cells. These materials were employed due to favourable charge carrier mobility and good optical absorption associated with them respectively. These photovoltaic devices were characterised by current–voltage (I-V) measurement under illumination, and interpreted on the basis of charge transfer due to different SiNW concentrations. Morphology characterisation shows that the SiNWs are randomly distributed across the active area, and that the film becomes progressively inhomogeneous upon excess addition of SiNWs. The UV–Vis and PL spectra suggest changes in absorption and emission characteristics upon SiNW incorporation into the rr-P3HT blended matrix, which assist with the interpretation of the charge transfer mechanism.

A new Pt-Al2O3 double cermet selective solar absorber configuration was prepared using magnetron sputtering system at room temperature. The Scanning Electron Microscopy (SEM) investigations showed that the surface of the Pt-Al2O3 double cermet coating was characterized by a granular structure, while AFM and cross-section SEM analysis revealed a columnar structure with an average height of 45.4 ± 0.1 nm and a surface roughness of 21.1 nm. EDS analysis confirmed the chemical purity of the without any detectable impurities. The coatings showed a combination of a high selective solar absorptance of 0.97 and a thermal emittance of 0.18 at 400 °C, which is better than almost all Al2O3, based selective solar absorbers reported so far. An optical analysis revealed that these favorable properties arise from a combination of interference, and light trapping/absorption effects that occur in the multilayered columnar solar absorber coating. The Pt-Al2O3 cermet showed an excellent photo-thermal conversion efficiency of 88%.

A diffusion kinetics study of implanted silver (Ag) ions into SiC films is conducted. SiC thin films have been processed on Si (1 0 0) substrates by electron beam deposition from a commercial high purity hot-pressed SiC sheet. The as-deposited films were thereafter implanted with Ag+ ions. Realtime Rutherford backscattering spectrometry experiments showed that Ag+ is stable until 600 °C, which is the highest temperature that the heater in the system used could achieve. Conventional RBS studies on isochronally annealed films at higher temperatures in the range between 650 °C and 950 °C reveal that there is no significant change in the spectra up to a temperature of ∼ 750 °C. At 850 °C a change in the Ag implantation profile was observed, suggesting that Ag is mobile at that temperature. The corresponding depth profile at 850 °C suggests that there is significant Ag in- diffusion, however the overall integrated intensity data indicate that most of the Ag+ is escaping out of the films. Upon annealing for one hour at 950 °C, all the Ag ions have essentially escaped out of the films and/or spread throughout the layer below the detection limit of RBS. Isothermal annealing studies over varied duration times at 850 °C confirm Ag in-diffusion, but at the same time there is evidence of depletion of Ag near-surface regions as the annealing time increases; the overall out-diffusion of the implanted metal, although steady, is found to be slow in an isothermal process. FTIR investigations point to a diffusion model through pores and grain boundaries.

Lead iodide (PbI2) thin films were grown and converted to methyl ammonium lead triiodide (MAPbI3) perovskites through a two-step chemical vapour deposition process, addressing the issue of stable and scalable synthesis of perovskites layers. High quality, stable under open air, large perovskite grains close to micrometre size with full surface coverage were realised after 60 min conversion from the pre-deposited PbI2. The relationship between the PbI2 layer deposited in the first step and the converted perovskite is discussed. The performance of the planar perovskite device was investigated with different thicknesses of the hole transport layer under open air. The devices performed relatively poor with highest efficiency of 4.35% obtained when a thicker hole transport layer thickness used, which is attributed to protruding grains of perovskite film through the hole transport layer, thereby corroding the silver metal electrode.

The integration of noble metals nanostructures can be an effective method to improve the performance of organic solar cells by scattering the incident light that reaches the active layer. The resulting elongated active optical trail span of the incident photons can enhance the amount of absorbed photons in the active layer. Herein, this article reviews studies on the incorporation of noble metals and metal oxides nanostructures into bulk heterojunction polymer solar cells (BHJ PSCs) device architectures. In particular, we focus on presenting the latest progress in PCSs employing various fullerene electron acceptors with an emphasis on their performances, optical and structural properties upon integration of the mentioned nanostructure. We discuss the effect of metallic nanoparticles (NPs) integration, such as gold (Au) and silver (Ag), on the performance of PSCs according to theoretical interpretation. In addition to the metallic NPs, we discuss the influence of metal oxide nanoparticle incorporation, such as CuO, ZnO and TiO2, on the performance of the organic based solar cells.

The study report on Vanadium dioxide thin films of about 100nm thickness deposited using pulsed laser deposition on Si (100). The novel phase change reported is attributed to the post-treatment of the films via ion implantation with 25 KeV C+ ion beam at varying particle fluence (1E15, 1E16, and 1E17 /cm2). At the initial fluence, the preferred phase is retained while amorphization and recrystallization of the film is observed as the fluence increase to 1E16 ions/cm2and 1E17 ions/cm2, respectively. The phase transition of the samples is observed to occur at a temperature below 320 K while stabilization of the low phase structure is observed for the middle fluence. Further increase restores the SMT behaviour/trend that occurred at elevated temperatures.

Planar perovskite solar cells (PPSCs) have received great attention in recent years due to their intriguing properties, which make them a good choice for photovoltaic applications. In this work, the effect of alkali and transition metal-doped TiO2 (cesium-doped TiO2 (Cs-TiO2) and yttrium-doped TiO2 (Y-TiO2)) compact layers on the optical, structural and the photovoltaic performance of the PPSCs have been investigated. The perovskite layer syntheses were carried out by depositing a lead iodide (PbI2) layer via spin-coating; converting PbI2 into methyl ammonium iodide (CH3NH3PbI3) by chemical vapor deposition (CVD) and spin-coating at 60 min and 60 s conversion times respectively. The as-deposited PPSCs were studied layer-by-layer using an X-ray diffractometer, scanning electron microscope, and UV-vis diffuse reflectance, transmittance and absorbance. The power conversion efficiency for stable processed perovskite solar cells were 3.61% and 12.89% for air and vacuum processed, respectively.

Pd(50 nm)/Ti(25 nm)/Pd(50 nm) multilayer stack has been deposited on Ti and Ti6Al4V substrates; we have studied the intermixing of layers upon annealing at the hydrogenation temperature of 550 °C, under vacuum, H/Ar gas mixture and pure hydrogen atmospheres. Scanning electron microscopy (SEM) micrographs indicated surface roughening in samples annealed under vacuum and H/Ar gas mixture while those annealed under pure H2 remained relatively smoother. Rutherford backscattering spectrometry (RBS) revealed intermixing of layers as evidenced by the diffusion of Pd toward the bulk, while XRD indicated the formation of PdTi2 phase in the samples annealed under vacuum and H/Ar gas mixture atmosphere. In-situ, real-time RBS showed that the annealing under pure H2 preserves the integrity of the Pd catalyst. No indication of the PdTi2 formation in the pure H2 annealed samples was observed; instead only the TiH2 phase appeared, indicating the absorption of H into the system.

Mechanism for the formation of titanium oxynitride (TiO2-xNx) on the surfaces of spherical Ti powder particles upon heat treatment in air at 500, 600, 700 and 800 °C was investigated. The results showed that the first at 500 °C a hexagonal closed packed (HCP) TiOx film was formed while aTiO2 film was observed after annealing at 600 °C and eventually a TiO2-x-Nx layer coated the spherical Ti particles at 700 and 800 °C due to N diffusion within the TiO2 crystal lattice. The resulting surface structure was studied by means of x-ray diffraction (XRD) while the surface morphology of the powders was characterized using the scanning electron microscope (SEM) attached with energy dispersive x-ray spectroscopy (EDS) detector. The AFM images confirmed that when the N content increases (800 °C-heat treated sample) the powder loses its triangular grains (700 °C-annealed sample) to irregular shaped grains.

In this article, we used a two-step chemical vapor deposition (CVD) method to synthesize methylammonium lead-tin triiodide perovskite films, MAPb1−xSnxI3, with x varying from 0 to 1. We successfully controlled the concentration of Sn in the perovskite films and used Rutherford backscattering spectroscopy (RBS) to quantify the composition of the precursor films for conversion into perovskite films. According to the RBS results, increasing the SnCl2 source amount in the reaction chamber translate into an increase in Sn concentration in the films. The crystal structure and the optical properties of perovskite films were examined by X-ray diffraction (XRD) and UV-Vis spectrometry. All the perovskite films depicted similar XRD patterns corresponding to a tetragonal structure with I4cm space group despite the precursor films having different crystal structures. The increasing concentration of Sn in the perovskite films linearly decreased the unit volume from about 988.4 Å3 for MAPbI3 to about 983.3 Å3 for MAPb0.39Sn0.61I3, which consequently influenced the optical properties of the films manifested by the decrease in energy bandgap (Eg) and an increase in the disorder in the band gap. The SEM micrographs depicted improvements in the grain size (0.3–1 µm) and surface coverage of the perovskite films compared with the precursor films.

Lead halide thin films, such as lead iodide (PbI2) and lead chloride (PbCl2), are used as precursor films for perovskite preparation, which is frequently achieved by vacuum thermal evaporation but rarely by the low-pressure chemical vapor deposition (CVD) method. Here, we report on the deposition of PbI2 and PbCl2 thin films on glass substrates by employing the low-pressure CVD method. The effect of the substrate temperature on the structure and morphology of the lead halide films is investigated. Crystalline films were realized for both lead halides, with PbI2 films showing high texture compared to the reduced texture of the PbCl2 films. Large lateral grain sizes were observed for the PbI2 films with a flat platelet grain morphology and an average grain size up to 734.2 &plusmn, 144.8 nm. PbCl2 films have columnar grains with an average grain size up to 386.7 &plusmn, 119.5 nm. The PbI2 films showed a band gap of about 2.4 eV, confirming its semiconducting properties, and the PbCl2 had a wide band gap of 4.3 eV, which shows the insulating properties of this material.

Planar perovskite solar cells (PPSCs) have received great attention in recent years due to their intriguing properties, which make them a good choice for photovoltaic applications. In this work, the effect of alkali and transition metal-doped TiO

A set of various perovskite precursor formulations was investigated to elucidate correlations between precursor composition and the crystal structure, film morphology as well as photovoltaic activity of H3CNH3PbI3-xClx perovskite solar cells. Three precursor solutions in dimethylfromamide (DMF) with defined ratios of lead(II) halide (PbI2 and/or PbCl2) and methylammonium halide (H3CNH3I (MAI) and H3CNH3Cl (MACl)) such as 1:3 (PbCl2:MAI), 1:1:4 (PbI2:PbCl2:MAI) and 1:1:1 (PbI2:MAI:MACl) were used to prepare solar cells in primarily ambient atmosphere. Processing the 1:3 (PbCl2:MAI) solution in ambient atmosphere yielded perovskite films with rather non-uniform morphology and devices with moderate performance. Perovskite thin films prepared from the 1:1:4 (PbI2:PbCl2:MAI) and 1:1:1 (PbI2:MAI:MACl) formulation showed nearly identical features, high crystallinity, large and compact micrometer-sized crystal domains, and good photovoltaic performance. This indicates that the overall ionic composition in the precursor solution is crucial for the perovskite formation, the source of these ions, however, appears nonrelevant. Furthermore, the effect of different electron transport layers (ETL), PCBM, bis-PCBM, and N-[4-(benzothiadiazol-4-yl)phenyl]-N′-(1-nonyldecyl)perylene-3,4,9,10-tetracarboxdimide (a-PTCDI) on the photovoltaic performance was analyzed. The highest hysteresis-free power conversion efficiency (PCE) was achieved with PCBM (12.8%) followed by a-PTCDI (8.4%) and bis-PCBM (6%). The degradation of MAPbI3-xClx based devices stored in nitrogen atmosphere was primarily revealed by a loss in fill factor.

This contribution reports on the bioremediation of the industrial textile effluent by the valorization of agro-waste extracts of Rosmarinus officinalis (rosemary) leaves using biosynthesized Ag-doped ZnO nanoparticles (NPs), as photocatalysts. Characterization of the NPs was carried out using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), UV-Visible, photoluminescence (PL), and efficacy in the photocatalytic degradation of dyes in non-synthetic industrial textile effluent. FESEM and XRD results depicted the hexagonal structure of the Ag-doped ZnO NPs with the average particle size of 21.65 ± 0.25 nm for FESEM, in the range of 7.450-38.611 nm from Scherrer equation and 28.946 ± 0.002 nm from the Williamson-Hall plot for XRD. EDS indicated Ag (3.94%), Zn (41.01%), and O (30.52%) atoms in the sample, and the carbon (24.53%) attributed to the phenolic compounds in the plant extract, while ATR-FTIR identified stretching vibration mode of Ag-O and Zn-O at 476 cm−1 and 840 cm−1, respectively. From UV-Vis-NIR, the energy bandgap has amounted to 3.23eV and the photoluminescence emission spectrum indicated the existence of surface defects and oxygen vacancies. Synthesized NPs were used for the treatment of the industrial textile effluent (TE) by assessing the pH and temperature, total suspended solids (TSS), biochemical oxygen demand after 5 days (BOD), chemical oxygen demand (COD). The mineralization thus decontamination of the TE has been confirmed with 63 % degradation of the dye being observed after 100 min visible light exposure. The analyses reported herein indicated that this plant extract synthesized nanoparticles can play an important role in the bioremediation of textile industry wastewater.

The adsorption of phosphoric acid anions on the platinum (111) plane is investigated using Monte Carlo and density functional theory methods. The minimum energy structure is used to generate the adsorption configurations, indicating the preferred adsorption sites. The bond lengths was found from density functional theory calculations and used to gain further insight on the structure due to adsorption. From the density functional calculations the scanning tunnelling microscopy image of the specie with the lowest adsorption energy configuration and shortest bond length was produced.

Biosynthesized Zincite nanoparticles have been successfully demonstrated by a completely green process mediated aqueous extract of rosemary leaves acting as both reducing and stabilizing agents and zinc nitrate hexahydrate as the precursor. The synthesis was free of solvents and surfactants to adhere to green chemistry principles and the impartation of environmental benignity. To achieve our objective, structural and optical investigations of ZnO annealed at 500°C for 2hrs were carried-out using complementary techniques. High resolution transmission electron microscopy (HRTEM) revealed the self-assembled, highly agglomerated quasi-hexagonal shaped NPs and the average particle size was found to peak at 15.62 ± 0.22 nm. Selected area electron diffraction (SAED) and X-ray diffraction (XRD) exhibited several diffraction rings with clear diffraction spots confirming their polycrystallinity and the purity of ZnO NPs with a wurtzite structure. Furthermore, the energy dispersive X-ray spectroscopy (EDS) substantiated the presence of Zn and O in the sample and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) illustrated the Zn-O chemical bonds. From UV-Vis-NIR, the optical band gap was amounted to 3.2 eV and photoluminescence (PL) emission spectrum to 2.9eV with high surface defects and oxygen vacancies. Through these results, the use of rosemary leaves extract is hereby shown to be a cost-effective and environmentally friendly alternative to synthesize Zincite nanoparticles (ZnO NPs).

We report on the non-enzymatic glucose sensing ability of elemental Cu doped Co3O4 thin film deposited on FTO in this study. A facile chemical solution method was used to substitute elemental Cu into the Co3O4 host lattice. The morphology of the electrode was characterized by XRD, SEM, HRTEM, SAED and EELS. The as prepared thin film exhibited very high sensitivity of 1850 μAcm-2 mM−1, and linear range up to 7.6 mM. The sensor showed a limit of detection of 153 nM at a signal to noise ratio of 3. The developed sensor was used successfully to measure glucose level in human serum and spiked saliva samples. Keywords: Co3O4, Non-enzymatic sensor, Glucose sensor, Thin film

Although metal-catalysts are commonly used to create nanoscale materials at surfaces, little is quantitatively known or understood about the depth distribution profile of the catalyst during the growth process. Using X-ray reflectivity, we report the first quantitative investigation, with nanoscale resolution, of the Ag metal-catalyst depth distribution profile during metal-assisted chemical etch (MACE) growth of Si nanowire (SiNW) arrays on Si(100). Given the very low optical reflectivity of these nanowire arrays, specular reflection from these materials in the X-ray region is extremely challenging to measure because it probes interfaces on the nanoscale. Nevertheless, we demonstrate that with suitable investigation, X-ray specular reflection can be measured and utilized to obtain unique structural information about the composition profile of both Ag and Si. The measurements, which also include X-ray diffraction and complementary electron microscopy, reveal that the Ag nanoparticles distribute along the length of the nanowires upon etching with a Ag density that increases towards the etch front. The Ag nanoparticles coarsen with etch time, indicating a high mobility of Ag ions even though we also find that the Ag does not migrate from the SiNW region into the etch bath during etching. The Ag density gradient and the Ag mobility suggest the existence of a strong chemical force that attracts Ag towards the etch front. These results provide unique and important new insight into the growth process for creating SiNWs from wet chemical etching using metal-catalysts.

We report on the fabrication and opto-electronic characterization of solution-processed planar heterojunction perovskite solar cells based on methylammonium (MA) lead halide derivatives, MAPbI3−xYx (Y = Cl, Br, I). Dissolving equimolar amounts of lead iodide (PbI2) and methylammonium iodide (H3CNH3I) together with various amounts of additional methylammonium halides, perovskite precursor solutions were obtained, which were used in the fabrication of three perovskite systems, MAPbI3, MAPbI3−xClx and MAPbI3−xBrx. The effect of the halide ratio in the perovskite formulations processed via a one-step deposition technique on optoelectronic properties and on photovoltaic performance of the formed perovskites was investigated. The perovskite film morphology, temperature-dependent photoluminescence properties, hysteresis behaviour in current–voltage characteristics and the photovoltaic performance as a function of chemical composition were studied using microscopic, spectroscopic and photovoltaic characterization techniques. The power conversion efficiency was found to be dependent on MAPbI3−xYx (Y = Cl, Br, I) perovskite film morphology. By controlling perovskite precursor composition and stoichiometry, highest power conversion efficiencies of 9.2, 12.5 and 5.4% were obtained for MAPbI3, MAPbI3−xClx and MAPbI3−xBrx devices, respectively. In addition, the physical parameters of the mixed halide perovskites such as the exciton binding energy, exciton–phonon interaction and bandgap were determined via temperature-dependent photoluminescence spectroscopy. Exciton binding and optical phonon energies of MAPbI3−xYx (Y = Cl, Br, I) were found to be in the ranges of 49–68 meV and 29–32 meV respectively. The solution-processed MA lead halide derivatives form highly crystalline materials with chemical versatility allowing the tuning of their optical and electronic properties depending on the nature and the ratio of the halides employed.

The deposition of a compact amorphous silicon/nano-crystalline silicon material is demonstrated by hot-wire chemical vapour deposition using a sequential hydrogen profiling technique at low hydrogen dilutions. Nano-crystallite nucleation occurs at the substrate interface that develops into a uniform, porous crystalline structure as the growth progresses. A further reduction in the H-dilution results in the onset of a dense amorphous silicon layer. The average crystalline volume fraction and nano-crystallite size in the sample bulk amounts to 30% and 6 nm, respectively, as probed by Raman spectroscopy using the 647 nm excitation. The change in hydrogen dilution is accompanied by a graded hydrogen concentration depth-profile, where the hydrogen concentration decreases as the growth progresses. The level of post-deposition oxidation is considerably reduced, as inferred from infrared spectroscopy. The presence of oxygen is mainly confined to the substrate interface as a result of thermal oxidation during thin film growth.

Copyright: 2016 Wiley. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item. For access to the full text item, kindly consult the publisher's website.

This study examines the correlation between the chemical, electronic and optical properties of a nanocrystalline silicon thin film fabricated by hot-wire chemical vapour deposition. The locations of porosity and the incubation layer of the thin film can be monitored by tracking the SiH2 and SiH signals, respectively, from time of flight secondary ion mass spectrometry. High resolution transmission electron microscopy shows that the mean nanocrystallites size is larger along the growth direction. Electron energy loss spectroscopy reveals a reduction in the intensity of the Si L-edges spectra, i.e. reduced transitions from the silicon 2p band to the conduction band, within the incubation layer and a subsequent recovery thereafter moving along the crystalline cone regions. Despite the presence of porosity, the oxygen within the nanocrystalline silicon thin film is predominately at the surfaces of the film and the interface region with the crystalline silicon substrate. Knowledge of these evolving features of the nanocrystalline silicon thin film were then taken into consideration during the construction of an optical model based on the effective mass approximation, which then allows for the accurate determination of the film thickness based on basic UV–Vis spectroscopy.

This report focuses on the synthesis of novel 2,3,4,5-tetrathienylthiophene-co-poly(3-hexylthiophene-2,5-diyl) (TTT-co-P3HT) as a donor material for organic solar cells (OSCs). The properties of the synthesized TTT-co-P3HT were compared with those of poly(3-hexylthiophene-2,5-diyl (P3HT). The structure of TTT-co-P3HT was studied using nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FTIR). It was seen that TTT-co-P3HT possessed a broader electrochemical and optical band-gap as compared to P3HT. Cyclic voltammetry (CV) was used to determine lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy gaps of TTT-co-P3HT and P3HT were found to be 2.19 and 1.97 eV, respectively. Photoluminescence revealed that TTT-co-P3HT:PC71BM have insufficient electron/hole separation and charge transfer when compared to P3HT:PC71BM. All devices were fabricated outside a glovebox. Power conversion efficiency (PCE) of 1.15% was obtained for P3HT:PC71BM device and 0.14% was obtained for TTT-co-P3HT:PC71BM device. Further studies were done on fabricated OSCs during this work using electrochemical methods. The studies revealed that the presence of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) on the surface of indium tin oxide (ITO) causes a reduction in cyclic voltammogram oxidation/reduction peak current and increases the charge transfer resistance in comparison with a bare ITO. We also examined the ITO/PEDOT:PSS electrode coated with TTT-co-P3HT:PC71BM, TTT-co-P3HT:PC71BM/ZnO, P3HT:PC71BM and P3HT:PC71BM/ZnO. The study revealed that PEDOT:PSS does not completely block electrons from active layer to reach the ITO electrode.

Producing active thin films coated on supports resolves many issues of powder-based photo catalysis and energy harvesting. In this study, thin films of C-N-TiO2 were prepared by dynamic spin coating of C-N-TiO2 sol-gel on glass support. The effect of spin speed and sol gel precursor to solvent volume ratio on the film thickness was investigated. The C-N-TiO2-coated glass was annealed at 350 &deg, C at a ramping rate of 10 &deg, C/min with a holding time of 2 hours under a continuous flow of dry N2. The C-N-TiO2 films were characterised by profilometry analysis, light microscopy (LM), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The outcomes of this study proved that a spin coating technique followed by an annealing process to stabilise the layer could be used for immobilisation of the photo catalyst on glass. The exposure of C-N-TiO2 films to UV radiation induced photocatalytic decolouration of orange II (O.II) dye. The prepared C-N-TiO2 films showed a reasonable power conversion efficiency average (PCE of 9%) with respect to the reference device (15%). The study offers a feasible route for the engineering of C-N-TiO2 films applicable to wastewater remediation processes and energy harvesting in solar cell technologies.

We report on the structural and electrical properties of Mg ion implanted semiconductor-metal transition of vanadium dioxide thin films with three different ion fluences. The effect of introducing Mg implants showed interchange, rearrangement, and modification of atoms in the lattice structure of VO2. The (011) monoclinic signature of VO2 is significantly affected; (i) peak broadening and shift of the peak position to lower angles at 1 × 1015 ions/cm2, (ii) revert and shift towards high angles at 1 × 1016 ions/cm2 and (iii) ceasing to exist at 1 × 1017 ions/cm2 suggesting a complete devolution of the VO2 thin films at higher fluence. Composition and profiling of the V-O matrix revealed a corresponding decrease of the vanadium edge peak at 1 × 1017 ions/cm2 and a decrease of the oxygen content in implanted films. Whilst the carrier concentration is increased, the magnitude of the semiconductor-metal transition of implanted VO2 thin films is significantly affected with a decrease of career mobility. Whilst increasing ion fluence above 1 × 1017 ions/cm2 at a depth of 40 nm, the Mg implants move relatively towards the surface of VO2 resulting in the loss of the characteristic thermochromism of VO2 films.

We report for the first time on the gas sensing properties of novel ball milled and nitrided Mg-TiO 2 prepared powder. Ball milling was performed on an Mg-TiO 2 powder mixture for 60 hours (h), yielding a reduction in crystallite sizes. The milled powder was annealed in nitrogen at 650 °C, and crystalized into two face centred cubic (FCC) phases with different lattice parameters. The nitrided powder sample exhibited various morphologies including nanorods, as well as nanoparticles showing porous behaviour. The AFM and BET analyses showed high roughness and surface area for 60 h milled Mg-TiO 2 nanostructures. The Mg-TiO 2 60 h and Mg-TiO 2 -60 h-N 2 materials were tested for their sensing performance towards H 2 , NH 3 and CH 4 gases at various temperatures. The Mg-TiO 2 60 h sensing material showed high sensing response to NH 3 , disclosing fast response-recovery time and high selectivity to NH 3 .

Nitridation of ball-milled Mg–TiO2 and Mg–Sn–TiO2 has yielded the formation of mixed metal oxynitride powders including the spinel-type. Structural development was traced by using x-ray diffraction (XRD) technique and confirmed by using the Raman spectroscopy.

Metastable MgO x N y compound was synthesized through annealing under the mixture of nitrogen–oxygen gases. The nanocrystalline particles of different morphology were formed. Powders were characterized by XRD, SEM, TEM, Raman spectroscopy. A complete synthesis of MgO x N y was obtained upon annealing at 650 °C with low BET surface area when compared to Mg 3 N 2 powder.

This contribution reports on the effect of thermal annealing on sputtered Pt–Al2O3 multilayered selective solar absorber coatings deposited onto stainless steel substrates with a Mo IR reflecting buffer layer. The Pt–Al2O3 cermet nanocoatings were annealed at different temperatures for different durations in vacuum. The spectral selectivity of the optimised Pt–Al2O3 was found to be thermally stable up to 900 °C in vacuum for 2 h with solar absorptance of 0.944 and thermal emittance of 0.11. At 1000 °C, its spectral selectivity decreased significantly to 0.892/0.13, which is attributed to the inter-diffusion between the layers, and formation of η-Fe3Mo3C phase. Annealing the Pt–Al2O3 nanocoatings for long term showed that the cermet nanocoatings were thermally stable up to 800 °C in vacuum for 24 h having spectral selectivity of 0.938/0.10.

We report the effects of substrate temperatures on the thermal stability of AlxOy/Pt/AlxOy multilayered selective solar absorber coating (MSSAC). The samples were deposited at different substrate temperatures (from room temperature up to 250 °C), and then annealed at various temperatures (300–600 °C) in air for 2 h. Characterizations are made via X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Atomic Force Microscopy (AFM), Raman Spectroscopy, UV–Vis and emissometeric measurements. These coatings were found to be thermally stable up to 500 °C with good spectral selectivity of 0.930/0.11. Furthermore, the observed decrease in the spectral selectivity 0.883/0.13 at 600 °C is attributed to the diffusion of Cu and the formation of CuO phase. Such phase formation was confirmed using XRD and Raman spectral analysis. The insensitiveness of the thermal stability of such coatings on the substrate temperature is demonstrated.

We report on the correlation between defect-related emissions, the magnetization and sensing of TiO2 nanoparticles (NPs) prepared by milling method. Surface morphology analyses showed that the size of the TiO2 NPs decreases with milling time. Raman and XRD studies demonstrated that the structural properties of the TiO2 transform to orthorhombic structure upon milling. Magnetization improved with an increase of a defect-related band originating from oxygen vacancies (VO), which can be ascribed to a decrease in the size of the NPs due to the milling time. Moreover, the longer-milled TiO2 exhibited enhanced gas-sensing properties to humidity in terms of sensor response, with about 12 s response time at room temperature. A combination of photoluminescence, X-ray photoelectron spectroscopy, vibrating sample magnetometer and sensing analyses demonstrated that a direct relation exists between the magnetization, sensing and the relative occupancy of the VO present on the surface of TiO2 NPs.

Ball milling of titanium mixed stearic acid yields the formation of the metastable face centred cubic phase upon sintering and water quenching at 1200 °C. Structural transformation was traced by the X-ray diffraction technique. Phase transformations were investigated by differential scanning calorimetry in flowing argon gas. The optical microstructure illustrated the needle and lath type morphology attributable to nonstoichiometric titanium hydride phase. In addition, the microstructure monitored by the scanning electron microscopy show the nonstoichiometric titanium carbide phase segregating along the grain boundaries. As a result, high average hardness value of 654 and 670 Vickers hardness was measured for sintered and quenched 15 h milled titanium–stearic acid.

Phase transformation was induced by ball milling and annealing of Ti75–Sn25 powder. HCP solid solution was induced by Ball milling and yielded a compressed lattice parameters a = 2.929 A; c = 4.780 A and c/a = 1.63. Upon annealing in Ar at 700 °C, Ti3Sn intermetallic with lattice parameters a = 5.916 A; c = 4.764 A with (c/a = 0.80) was detected. Subsequent TGA analysis of HCP milled Ti–Sn and Ti3Sn intermetallic in air have resulted in tetragonal oxynitride powders with lattice parameters a = 4.985 A; c = 2.962 A, c/a = 0.594 for the former and a = 4.582 A; c = 2.953 A and c/a = 0.644 for the latter, respectively. The powder morphology was monitored by the high-resolution transmission electron microscopy while the roughness of the milled was analysed by the atomic force microscopy. Phase transformation was monitored by the X-ray diffraction and complemented by the Raman spectroscopy.

It is well known that nitriding of titanium is suitable for surface coating of biomaterials and in other applications such as anti-reflective coating, while oxygen-rich titanium oxynitride has been applied in thin film resistors and photocatalysis. Thus in this work anatase was reduced with pure titanium powder during annealing in argon. This was done to avoid any metallic contamination and unwanted residual metal doping. As a result, interesting and different types of particle morphology were synthesized when the pre-milled elemental anatase and titanium powders were mixed. The formation of metastable face centred cubic and monoclinic titanium monoxide was detected by the X-ray diffraction technique. The phases were confirmed by energy dispersive X-ray spectroscopy analysis. Raman analysis revealed weak intensity peaks for samples annealed in argon as compared to those annealed under nitrogen.

Electron backscatter diffraction revealed that during the hot-wire deposition of silicon nitride, a tantalum filament partially transformed to some of its nitrides and silicides. The deposition of an encapsulating silicon nitride layer occurred at the cooler filament ends. Time-of-flight secondary ion mass spectroscopy disclosed the presence of hydrogen, nitrogen and silicon containing ions within the aged filament bulk. Hardness measurements revealed that the recrystallized tantalum core experienced significant hardening, whereas the silicides and nitrides were harder but more brittle. Crack growth, porosity and the different thermal expansion amongst the various phases are all enhanced at the hotter centre regions, which resulted in failure at these areas.

TiO 0.61 N 0.29 was synthesized by annealing of ball milled Ti in air at 900 °C for 5 h. In addition, traces of rutile-type TiO 1.56 N 0.56 phases were observed. The morphology of the synthesized powder displayed multiple interesting colours. Scanning electron microscopy, X-ray diffraction and Raman spectroscopy were used for characterization of the powders. Raman analyses showed a phase transformation upon annealing in air.