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Aluminium doped zinc oxide thin films are prepared by Radio Frequency magnetron sputtering in pure argon atmosphere at 100W. The structural results reveal good film adhesion on a silicon substrate (001). The thin films were then subjected to heat treatment in a furnace under ambient air. The structural, morphological and optical properties of the thin films as a function of deposition time and annealing temperatures have been investigated using Grazing incidence X-Ray Diffraction (GIXRD), Atomic Force Microscopy and Scanning Electronic Microscopy. The photoluminescence properties of the annealed films showed significant changes in the optical properties attributed to mid gap defects. Annealing increases the crystallite size and the roughness of the film. The crystallinity of the films also improved as evident from the Raman and XRD studies. [ABSTRACT FROM AUTHOR]

Equilibrium phases of the Bi2O3-WO3 system, synthesized using the citrate-gel method with slow cooling, have been systematically investigated for samples with 22–27 mol% WO3. Annealing temperature and content of WO3 were shown to play a significant role in the phases present. Both powder X-ray diffraction and Raman spectroscopy revealed that the room temperature equilibrium phases were 7Bi2O3-WO3 and 7Bi2O3-2WO3, with the latter being dominant. Variable temperature Raman spectroscopy showed that both these phases were present up to 850 °C, with the possible formation of a third unidentified phase at higher temperatures. The ionic conductivities of the mixed-phase materials were between that for the pure 7Bi2O3-WO3 and 7Bi2O3-2WO3 phases and at 700 °C was only about three times lower than that of the pure defect fluorite phase of the 22 mol% WO3 samples. The Arrhenius plots showed no sudden increase in conductivity between 300 and 750 °C providing evidence that no major phase change occurred in this temperature range. [ABSTRACT FROM AUTHOR]

The energy storage performance of one of the lightest-known MXenes, Ti2CTx (MX) combined with carbon nanospheres (CNS) has been investigated as a symmetric electrode system in an aqueous electrolyte (1 M Li2SO4). The energy storage properties were interrogated using cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), electrochemical impedance spectroscopy (EIS) and voltage-holding tests. The combined material (MX/CNS) demonstrated a higher specific capacity compared to each of the individual components. The material was fabricated with relatively high and low mass loadings, assembled into a symmetric device and performance compared. Specific capacitance, specific power and specific energy for the lower electrode mass loading of 180 F·g-1, 37.6 kW·kg-1 and 14.1 W·h·kg-1 were all higher than 86 F·g-1, 20.1 kW·kg-1 and 6.7 W·h·kg-1 for the higher mass loading. A wide voltage window of 1.5 V was obtained, but with limited long-term cycling behavior, suggesting the need for future improvement. Mathematical modelling and simulation of the supercapacitor showed good correlation with the experimental results, validating the model. The results reveal the potential of the Ti2CTx to be employed as a viable energy storage system for lightweight applications. [ABSTRACT FROM AUTHOR]

Down conversion has been applied to minimize thermalization losses in photovoltaic devices. In this study, terbium-doped ZnO (ZnO:Tb 3+ ) thin films were deposited on ITO-coated glass, quartz and silicon substrates using the RF magnetron sputtering technique fitted with a high-purity (99.99%) Tb 3+ -doped ZnO target (97% ZnO, 3% Tb) for use in organic solar cells as a bi-functional layer. A systematic study of the film crystallization dynamics was carried out through elevated temperature annealing in Ar ambient. The films were characterized using grazing incidence (XRD), Rutherford backscattering spectrometry (RBS), atomic force microscopy, and UV-visible transmittance and photoluminescence measurements at an excitation wavelength of 244 nm. The tunability of size and bandgap of ZnO:Tb 3+ nanocrystals with annealing exhibited quantum confinement effects, which enabled the control of emission characteristics in ZnO:Tb 3+ . Energy transfer of ZnO → Tb 3+ ( 5 D 3 - 7 F 5 ) was also observed from the photoluminescence (PL) spectra. At an inter-band resonance excitation of around 300-400 nm, a typical emission band from Tb 3+ was obtained. The ZnO:Tb 3+ materials grown on ITO-coated glass were then used as bi-functional layers in an organic solar cell based on P3HT:PCBM blend, serving as active layers in an inverted device structure. Energy transfer through down conversion between ZnO and Tb 3+ led to enhanced absorption in P3HT:PCBM in the 300-400 nm range and subsequently augmented J sc of a Tb 3+ -based device by 17%., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)