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Surface modification of sputter deposited γ-WO3 thin film for scaled electrochromic behaviour
摘要： In this research work, the synthesis and the electrochromic (EC) performance of the active material (γ-WO3) is reported. Nanoporous γ-WO3 thin ?lm was grown directly on the indium tin oxide (ITO) coated glass substrate using DC magnetron sputtering in a reactive environment (Ar:O2 = 2:1) at room temperature (RT). To achieve the nanoporous-nanocrystalline behaviour of the active material, a thermal treatment (250 °C) was given, which modi?ed the compact ?lm surface into nanospheres. This surface modi?cation is responsible to alter the physical, optical and electrochromic properties of the active material. The physical properties of the active material were probed in detail using X-ray di?raction (XRD), Field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and energy-dispersive X-ray analysis (EDX). The optical and electrochromic behaviour of the active electrode material was analyzed using UV–Vis spectroscopy and cyclic voltammetry (CV). It has been found that the modi?ed electrode exhibited large optical modulation (46%), high reversible redox behaviour (higher current density) and good cyclic stability at least upto 500 cycles, causes scaled EC behaviour. This electrochemically active architecture allow one to fabricate the device for energy harvesting applications. Our work indorse human comfort with ?nancial bene?ts and may play a crucial role in “green nanotechnology”.
关键词： Transmittance,WO3 thin ?lms,Sputtering,Nanoporous,Electrochromism
更新于2025-09-11 14:15:04
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Properties of Arsenic–Doped ZnTe Thin Films as a Back Contact for CdTe Solar Cells
摘要： As-doped polycrystalline ZnTe layers grown by metalorganic chemical vapor deposition (MOCVD) have been investigated as a back contact for CdTe solar cells. While undoped ZnTe ?lms were essentially insulating, the doped layers showed signi?cant rise in conductivity with increasing As concentration. High p-type carrier densities up 4.5 × 1018 cm?3 was measured by the Hall-e?ect in heavily doped ZnTe:As ?lms, displaying electrical properties comparable to epitaxial ZnTe single crystalline thin ?lms in the literature. Device incorporation with as-deposited ZnTe:As yielded lower photovoltaic (PV) performance compared to reference devices, due to losses in the open-circuit potential (VOC) and ?ll factor (FF) related to reducing p-type doping density (NA) in the absorber layer. Some minor recovery observed in absorber doping following a Cl-free post–ZnTe:As deposition anneal in hydrogen at 420 ?C contributed to a slight improvement in VOC and NA, highlighting the signi?cance of back contact activation. A mild CdCl2 activation process on the ZnTe:As back contact layer via a sacri?cial CdS cap layer has been assessed to suppress Zn losses, which occur in the case of standard CdCl2 anneal treatments (CHT) via formation of volatile ZnCl2. The CdS sacri?cial cap was e?ective in minimising the Zn loss. Compared to untreated and non-capped, mild CHT processed ZnTe:As back contacted devices, mild CHT with a CdS barrier showed the highest recovery in absorber doping and an ~10 mV gain in VOC, with the best cell e?ciency approaching the baseline devices.
关键词： solar cells,CdTe,metalorganic chemical vapor deposition (MOCVD),ZnTe:As back contact,thin ?lms
更新于2025-09-11 14:15:04
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Influence of different post-annealing temperatures on physical properties of La0.72Ca0.28MnO3:Ag0.2 thin films by pulsed laser deposition technique
摘要： La0.72Ca0.28MnO3:Ag0.2/LaAlO3 (100) thin ?lms, prepared by pulsed laser deposition, were post-annealed at di?erent temperatures in air. X-ray di?raction technique were used to analysize the orientation and lattice parameter, atomic force microscope (AFM) and scanning electronic microscope (SEM) were employed to characterize the surface morphology of the thin ?lms. Resistance vs. temperature (R-T) behaviors of the thin ?lms were tested with standard four-probe technique. The surface morphology results show that the grain size increases and crystalline quality of the ?lms are improved with increased annealing temperature up to 1200 °C, while the amount of grains also increases; R-T results illustrate that both the temperature coe?cient of resistance (TCR) and metal-insulator transition temperature (TMI) of the ?lms, increase with annealing temperature. In particular, TCR of thin ?lm (post-annealing at 1200 °C) reaches 28.8%·K?1, which makes such ?lms be promisingly applicated in thermal detectors near the room temperature.
关键词： Pulsed laser deposition technique,Electrical properties,La0.72Ca0.28MnO3:Ag0.2 thin ?lms,Surface morphology
更新于2025-09-11 14:15:04
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Investigations on photovoltaic performance of sol–gel derived BiFeO3-based heterostructures via compositional modification
摘要： In this paper, sol–gel is used to synthesize BiFeO3 (BFO), RGO/BFO, RGO/BFO/TiO2, TiCl4-modi?ed RGO/BFO/TiO2 and MAPI/RGO/BFO/TiO2 thin ?lms onto Pt/Ti/SiO2/Si substrate. RGO/BFO/TiO2 thin ?lm possesses high power conversion ef?ciency (g) of 3.11% and ?ll factor (FF) of 0.72, owing to the favorable effects of TiO2 and RGO on promoting electron transfer and electron injection, respectively. All the results indicate that BFO-based heterostructure thin ?lm is a promising candidate for designing solar energy devices.
关键词： Thin ?lms,Sol-gel preparation,Electrical properties
更新于2025-09-11 14:15:04
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CuO <sub/>4±δ</sub> Ultrathin Films Crystalline Properties
摘要： Ultrathin ?lms of the electron-doped compound Nd2 ?x Cex CuO4 ±δ (NCCO) were realized by dc sputtering technique. The ?lms were grown both on (001)-oriented SrTiO3 and nonstoichiometric SrTiO3 with Ti-rich defects. Also, the NCO parent compound, namely Nd2 CuO4 , was used as buffer layer to improve the crystalline properties because of the very small lattice parameter mismatch, as well as compatible depositions conditions, compared to NCCO. The morphological and structural characterization were carried out on several samples, by means of surface analysis techniques and X-ray diffraction, in order to optimize the growth procedure.
关键词： thin ?lms,sputtering,X-ray diffraction,superconductivity,Electron-doped (e--doped) compounds
更新于2025-09-09 09:28:46
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Structure and Stability of C:H:O Plasma Polymer Films Co-Polymerized Using Dimethyl Carbonate
摘要： C:H:O plasma polymer ?lms (PPFs) were deposited by means of plasma-enhanced chemical vapour deposition using the non-toxic, biodegradable organic compound dimethyl carbonate (DMC) at various plasma powers and pressures in order to control the degradation properties related to the carbonate ester group. Coating properties using pure DMC monomer vapours were compared to co-polymerized ?lms from gaseous mixtures of DMC with either ethylene (C2H4) or carbon dioxide (CO2) affecting deposition rate and chemical composition. C:H:O ?lm properties were found to depend primarily on the amount of oxygen in the plasma. To investigate the PPF stability during aging, changes in the composition and properties were studied during their storage both in air and in distilled water over extended periods up to 5 months. It was shown that aging of the ?lms is mostly due to oxidation of the plasma polymer matrix yielding slow degradation and decomposition. The aging processes and their rate are dependent on the intrinsic amount of oxygen in the as-prepared C:H:O ?lms which in turn depends on the experimental conditions and the working gas mixture. Adjustable ?lm properties were mainly attained using a pure DMC plasma considering both gas phase and surface processes. It is thus possible to prepare C:H:O PPFs with controllable degradability both in air and in water.
关键词： plasma polymerization,aging,degradability,thin ?lms,chemical composition
更新于2025-09-09 09:28:46