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Electrochromic device with Magnetron sputtered Tungsten Oxide (WO<sub>3</sub>) and nafion membrane: performance with varying Tungsten Oxide thickness- A report
摘要： Electrochromics is the emerging technology for energy conservation and indoor climatic control through smart windows. In this study we are reporting four layer electrochromic device: ITO (400nm)/ commercially procured Nafion (183μm) / WO3 (44nm to 200nm)/ ITO (400nm). The active area (A) of the electrochromic devices are 3cm2. The tungsten oxide (WO3) and ITO thin films have been deposited at room temperature (300 K) by reactive DC Magnetron sputtering. The sheet resistance of ITO is 20 ?/□. The “as deposited” WO3 films are amorphous and have high optical transmission (75%- 85%) in the visible spectrum. The optical band gap decreases with increasing thickness of WO3 thin films. The coloration efficiency (CE) of the electrochromic device increases with increasing thickness of the WO3 layer. The CE for the device with WO3 thickness 200 nm is 184 cm2/C: the highest reported so far for a hybrid electrochromic device. The increase in the CE with thickness has been explained (for the first time) by replacing the surface charge density (Q/A) with the volume charge density (Q/A*t) in the coloration efficiency formula derived from the Beer Lambert’s law.
关键词： coloration efficiency,electrochromism,nafion and Magnetron sputtering.,Tungsten oxide
更新于2025-11-19 16:56:35
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Ultra-selective fiber optic SPR platform for the sensing of dopamine in synthetic cerebrospinal fluid incorporating permselective nafion membrane and surface imprinted MWCNTs-PPy matrix
摘要： Surface plasmon resonance (SPR) based dopamine sensor is realized using the state-of-art technique of molecular imprinting over an optical fiber substrate. Polypyrrole (PPy) is depicted as an effective polymer for the imprinting of dopamine through a green synthesis approach. Sensitivity of the probe is enhanced by the augmenting effect of surface imprinting of dopamine in polypyrrole over multiwalled carbon nanotubes (MWCNTs). To ensure the permselectivity of the probe towards dopamine molecules, a cation exchange polymer, nafion, is utilized as a membrane over imprinted sites to reduce the interference from anionic analytes like ascorbic acid and uric acid at physiological pH. The probe is characterized for a wide range of dopamine concentration from 0 to 10-5 M in artificial cerebrospinal fluid. Various probe parameters are varied to maximize the sensitivity of the sensor. The sensor possesses 18.9 pM as the limit of detection (LOD) which is lowest of those reported in the literature. The manifestation of sensing probe over an optical fiber along with the improved LOD makes the approach highly advantageous in terms of stability, repeatability, online remote monitoring, fast response, and miniaturization for its in vivo/in vitro applications in clinical sensing of dopamine.
关键词： surface plasmon,dopamine,Optical fiber,polypyrrole,nafion,molecular imprinting,sensor,multiwalled carbon nanotube
更新于2025-10-22 19:40:53
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Vacuum-free, Room-temperature Organic Passivation of Silicon: towards Very Low Recombination of Micro/Nano-Textured Surface Structures
摘要： Crystalline silicon (c-Si) solar cells remain dominant in the photovoltaic (PV) market due to their cost-effective advantages. However, the requirement for expensive vacuum equipment and the power-hungry thermal budget for surface passivation technology, which is one of the key enablers of the high performance of c-Si solar cells, impede further reductions of costs. Thus, the omission of the vacuum and high-temperature process without compromising the passivation effect is highly desirable due to cost concerns. Here, we demonstrate a vacuum-free, room-temperature organic Nafion thin-film passivation scheme with an effective minority carrier lifetime (τeff) exceeding 9 ms on an n-type c-Si wafer with a resistivity of 1-5 Ω·cm, corresponding to an implied open circuit voltage (iVoc) of 724 mV and upper-limit surface recombination velocities (SRV) of 1.46 cm/s, which is a level that is in line with the hydrogenated amorphous Si film-passivation scheme used in the current PV industry. We find that the Nafion film passivation of Si can be enhanced in an O2 atmosphere and that the Nafion/c-Si interface oxidation should be responsible for the passivation mechanism. This highly effective passivation is also achieved on various micro/nano-textured Si surface structures from actual production, including a pyramidal surface and nanopore-pyramid hybrid structure with nanopores on the inclined plane of the pyramid. We develop an organic Nafion-passivated n-type back-junction Si solar cell to examine application in a real device. The open circuit voltage (Voc) of the solar cell with the Nafion passivation layer achieves a clear improvement (30.8 mV) over those without the passivation layer, resulting in an increase (1.5%) in the power conversion efficiency (PCE). These results suggest the potential use of these organic electronics with current Si microelectronics and a new strategy for the development of vacuum-free, low-temperature Si-based PVs at low cost.
关键词： passivation,Silicon,Nafion thin film,Photovoltaic
更新于2025-09-23 15:21:21
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Conductive Holea??Selective Passivating Contacts for Crystalline Silicon Solar Cells
摘要： Defect state passivation and conductivity of materials are always in opposition; thus, it is unlikely for one material to possess both excellent carrier transport and defect state passivation simultaneously. As a result, the use of partial passivation and local contact strategies are required for silicon solar cells, which leads to fabrication processes with technical complexities. Thus, one material that possesses both a good passivation and conductivity is highly desirable in silicon photovoltaic (PV) cells. In this work, a passivation-conductivity phase-like diagram is presented and a conductive-passivating-carrier-selective contact is achieved using PEDOT:Nafion composite thin films. A power conversion efficiency of 18.8% is reported for an industrial multicrystalline silicon solar cell with a back PEDOT:Nafion contact, demonstrating a solution-processed organic passivating contact concept. This concept has the potential advantages of omitting the use of conventional dielectric passivation materials deposited by costly high-vacuum equipment, energy-intensive high-temperature processes, and complex laser opening steps. This work also contributes an effective back-surface field scheme and a new hole-selective contact for p-type and n-type silicon solar cells, respectively, both for research purposes and as a low-cost surface engineering strategy for future Si-based PV technologies.
关键词： solar cells,PEDOT,Nafion,passivation,conductivity
更新于2025-09-23 15:21:01
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A charge-transfer resistance model and Arrhenius activation analysis for hydrogen ion transmission across single-layer graphene
摘要： Transmission rates for protons and deuterons across single-layer graphene embedded in Nafion | graphene | Nafion sandwich structures are measured as a function of temperature in electrochemical hydrogen pump cells. Rates of ion transmission through graphene are obtained in the form of area-normalized ion-transfer resistances, and are interpreted in terms of ion-exchange current densities and standard heterogeneous ion-transfer rate constants. An encounter pre-equilibrium model for the ion-transfer step is then used to provide rate constants for the fundamental microscopic step of ion (proton or deuteron) transmission across graphene. Application of this rate model to interpret variable-temperature data on proton and deuteron transmission rates provides values for the activation energy and pre-exponential factor for the fundamental ion transmission step across graphene. Activation energies obtained from the Arrhenius plots for proton and deuteron transmission are as follows; for proton, Eact = 48 ± 2 kJ mole-1 (0.50 ± 0.02 eV) and for deuteron, Eact = 53 ± 5 kJ mole-1 (0.55 ± 0.05 eV). The difference between these two values of approximately 5 kJ mole-1 is in good agreement with the expected difference in vibrational zero-point energies for O-H and O-D bonds, albeit with some uncertainty given the uncertainties in the activation energy values. Pre-exponential frequency factor values of 8.3 ± 0.4 x 1013 s-1 and is 4.7 ± 0.5 x 1013 s-1 were obtained for proton and deuteron transmission respectively across graphene. These pre-factor values are both quite large, on the order of the values predicted from the Eyring – Polanyi equation with a transmission coefficient near one. The ratio of 1.8 for the rate pre-factors (H/D) is in reasonable agreement with the value of 1.3 for the ratio of bond vibrational frequencies for O-H and O-D stretching, respectively. Taken together, these data support a model in which proton and deuteron transmission across graphene are largely adiabatic processes for which the differences in transmission rate at room temperature are due largely to differences in activation energies.
关键词： Nafion,proton transmission,Graphene,2D materials,hydrogen pumping
更新于2025-09-23 15:21:01
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Development of a ZnCdS@ZnS quantum dotsa??based label-free electrochemiluminescence immunosensor for sensitive determination of aflatoxin B1 in lotus seed
摘要： In this study, we designed a ZnCdS@ZnS quantum dots (QDs)–based label-free electrochemiluminescence (ECL) immunosensor for sensitive determination of aflatoxin B1 (AFB1). A Nafion solution assembled abundant QDs on the surface of a Au electrode as ECL signal probes, with specially coupled anti-AFB1 antibodies as the capturing element. As the reduction reaction between S2O8 2? in the electrolyte and QDs on the electrode led to ECL emission, the decreased ECL signals resulting from target AFB1 in the samples were recorded for quantification. We evaluated electrochemical impedance spectroscopy and ECL measurements along each step in the construction of the proposed immunosensor. After systematic optimization of crucial parameters, the ECL immunosensor exhibited a good sensitivity, with a low detection limit of 0.01 ng/mL for AFB1 in a wide concentration range of 0.05–100 ng/mL. Testing with lotus seed samples confirmed the satisfactory selectivity, stability, and reproducibility of the developed ECL immunosensor for rapid, efficient, and sensitive detection of AFB1 at trace levels in complex matrices. This study provides a powerful and universal analytical platform for a variety of analytes that can be used in broad applications for real-time analysis, such as food and traditional Chinese medicine safety testing, environmental pollution monitoring, and disease diagnostics.
关键词： Electrochemiluminescence immunosensor,Nafion,Lotus seed,Aflatoxin B1,ZnCdS@ZnS quantum dots,Label-free
更新于2025-09-23 15:19:57
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Synthesis of carbon quantum dots in a Nafion matrix: Precursor effect on the ion transport properties
摘要： Carbon quantum dots have been prepared in a Nafion? matrix via the hydrothermal treatment of organic precursors, and the swelling and ion transport properties of the prepared composite materials have been characterized.
关键词： Nafion matrix,ion transport properties,carbon quantum dots,hydrothermal treatment
更新于2025-09-16 10:30:52
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Multifunctional Effect of <i>p</i> ‐Doping, Antireflection, and Encapsulation by Polymeric Acid for High Efficiency and Stable Carbon Nanotube‐Based Silicon Solar Cells
摘要： Silicon solar cells among different types of solar energy harvesters have entered the commercial market owing to their high power conversion efficiency and stability. By replacing the electrode and the p-type layer by a single layer of carbon nanotubes, the device can be further simplified. This greatly augments the attractiveness of silicon solar cells in the light of raw material shortages and the solar payback period, as well as lowering the fabrication costs. However, carbon nanotube-based silicon solar cells still lack device efficiency and stability. These can be improved by chemical doping, antireflection coating, and encapsulation. In this work, the multifunctional effects of p-doping, antireflection, and encapsulation are observed simultaneously, by applying a polymeric acid. This method increases the power conversion efficiency of single-walled carbon nanotube-based silicon solar cells from 9.5% to 14.4% and leads to unprecedented device stability of more than 120 d under severe conditions. In addition, the polymeric acid-applied carbon nanotube-based silicon solar cells show excellent chemical and mechanical robustness. The obtained stable efficiency stands the highest among the reported carbon nanotube-based silicon solar cells.
关键词： doping,carbon nanotubes,silicon solar cells,antireflection,Nafion
更新于2025-09-11 14:15:04