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Polytetrafluoroethylenea??intercalated MXene membranes with good photothermal performance for enhanced laser ignition
摘要： Photothermal effect has been widely used in many areas such as cancer therapy, photothermal energy harvesting, and laser ignition. However, exploring reliable and efficient free-standing energy converter for enhancing the photothermal performance is still a challenge. Herein, free-standing membrane based on two-dimensional MXene (Ti3C2) nanosheets and polytetrafluoroethylene (PTFE) was fabricated and characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry, which demonstrated a drastic temperature rise by laser irradiation and was further used as energy converter for enhancing the photothermal performance of laser ignition. Furthermore, the initiating power of the laser initiator can be largely reduced by adding a thin layer of MXene/PTFE membrane above the B/KNO3 cylinder. This work can give great promise for MXene-based membranes as the laser energy converter for reducing the initiating energy and promote the development of laser initiators with low initiating energy.
关键词： membranes,optical properties,thermal properties,composites,optical and photovoltaic applications
更新于2025-09-23 15:19:57
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The effects of air, oxygen and water exposure on the sub-bandgap absorption, the electronic conductivity and the ambipolar diffusion length in highly crystalline microcrystalline silicon films for photovoltaic applications
摘要： Reversible and irreversible changes due to long term air and short term de-ionized water (DIW) or pure oxygen exposure were investigated in about 1 μm thick hydrogenated microcrystalline silicon (μc-Si:H) films deposited on rough glass substrates, thereby comparing highly crystalline with compact material. Time and temperature dependent dark conductivity, steady-state photoconductivity, the steady-state photocarrier grating and dual-beam photoconductivity methods have been used to study the effects. Standard measurement procedures defined previously have been carefully applied to record the changes after different treatments using the steady-state methods under light. After long term air exposure of highly crystalline μc-Si:H films, a thermal annealing step leads to an increase in dark conductivity (σD) and steady-state photoconductivity (σph) as well as to a significant increase in the sub-bandgap absorption. These effects are likely due to a reversible recovery from surface adsorbents in a porous microstructure after air exposure resulting in surface charge and Fermi level shifts in agreement with earlier results. Compact μc-Si:H films showed only marginal effects upon an annealing after long term air exposure suggesting much reduced susceptibility to surface adsorbent induced by Fermi level shifts. Five hours exposure to de-ionized water at 80 °C caused more than an order of magnitude increase in σD and σph and a substantial decrease in the sub-bandgap absorption spectrum in highly crystalline as well as in compact μc-Si:H films. In addition, minority carrier diffusion lengths measured by the steady-state photocarrier grating method improved significantly. The changes after exposure to water were not reversible upon our standard annealing procedure. Exposure to high purity oxygen gas at 150 °C resulted in similar effects like the exposure to DIW. Also here the changes in material properties were not reversible upon annealing. Results are discussed in terms of adsorption and chemical reactions on surfaces in the porous highly crystalline material versus the materials with more compact structures. Results are compared to earlier observations and consequences for device application will be indicated.
关键词： microcrystalline silicon,electronic conductivity,sub-bandgap absorption,photovoltaic applications,ambipolar diffusion length
更新于2025-09-19 17:13:59
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Effect of chlorination and fluorination of benzothiadiazole on the performance of polymer solar cells
摘要： In order to explore the effects of chlorine and fluorine on photophysical properties and the differences, in this work, we synthesized five new polymers, P1–P5, in which benzo[1,2-b:4,5-b]dithiophene as the electron donating and benzothiadiazole as electron withdrawing. Analysis of these five polymers showed that the introduction of Cl and F atoms can deeper the highest occupied molecular orbital of these polymers and enhance the absorption of light by the species, thereby improving Voc and Jsc. Chlorination has a stronger ability to reduce energy levels and broaden the absorption spectrum compared to fluorination. Among them, P2 showed an efficiency of 4.08% with Jsc of 11.28 mA/cm2, Voc of 0.79 V, and fill factor (FF) of 0.45. Since chlorination is easier than fluorination in terms of synthesis, it is advantageous for practical applications. Therefore, we think that chlorination should not be ignored when designing high efficiency photovoltaic materials, especially when their fluorinated counterparts have proven to have good properties.
关键词： optical properties,copolymers,optical and photovoltaic applications
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Industry Applications Society Annual Meeting - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Industry Applications Society Annual Meeting - Elimination of Phase Unbalance in Cascaded Multilevel Converters for Large-Scale Photovoltaic Grid Integration
摘要： Cascaded H-bridge converters (CHB) are ideal candidates for large-scale photovoltaic (PV) power plants because of their modular structure and the absence of bulky line frequency power transformer. To eliminate leakage current, isolated dc-dc converters are needed to connect the PV arrays to the H-bridges of CHB. These dc-dc converters extract maximum power from each PV array independently. Under partial shading conditions, the power generated in the three phases of CHB is different, leading to an unbalance in the grid currents. The existing methods to balance the grid currents require the converter to be overrated or operate at reduced PV power. So a new topology is proposed to distribute the power equally among the three phases of CHB without overrating the converter or reducing the PV power. This is achieved by using high-frequency transformers each having one primary and three secondaries. Simulation results are presented to validate the proposed topology.
关键词： grid integration,multilevel converter,phase unbalance,photovoltaic applications,Cascaded H-bridge (CHB) converter
更新于2025-09-16 10:30:52
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Nano-scale sulfurization of the Cu <sub/>2</sub> ZnSnSe <sub/>4</sub> crystal surface for photovoltaic applications
摘要： The objective of this study was to find an effective method to improve VOC without JSC loss for Cu2ZnSnSe4 (CZTSe) monograin layer solar cells. Sulfurization of the surface of the kesterite absorber layer may lead to enhanced device efficiency via band gap widening at the surface. Surface sulfurization was carried out in two steps: a CdS layer was first deposited onto the CZTSe crystals by a chemical solution deposition method, and then the CdS-coated CZTSe was annealed at elevated temperature in evacuated quartz ampoules. The thickness of the sulfurized surface of CZTSe crystals was varied by adjusting the thickness of the CdS layer (from 100 nm to 200 nm) and by modifying the temperature of the annealing process from 400 to 700 °C for 60 min. SEM, EDX and Raman analysis showed that the CdS layer still existed on the surface of CZTSe crystals after annealing at 400 °C. After annealing at higher temperatures, the CdS layer disappeared and a new surface layer was formed. Annealing at 570 °C resulted in secondary phases on the surface, which are probably caused by decomposition reactions on the CZTSe crystal surface. Annealing at 700 °C formed a well-crystallized Cu2ZnSn(S, Se)4 thin layer on the surface of the CZTSe crystals, which was confirmed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The Raman peak located at 331 cm?1 provides strong evidence that a wider band gap Cu2ZnSn(S, Se)4 surface layer is formed after the sulfurization while the CdS peak at 308 cm?1 has disappeared. Compositional profiles of EDX and XPS showed that S is located in the surface layer, but Cd has diffused into the bulk of the crystal and acts as a dopant. The content of S in Cu2ZnSn(S, Se)4 depended on the CdS layer thickness.
关键词： CZTSe,band gap engineering,sulfurization,solar cells,photovoltaic applications
更新于2025-09-16 10:30:52
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Electronic and optical properties of two propounded compound in photovoltaic applications, CsPbI3 and CH3NH3PbI3: By DFT
摘要： Halide perovskite compounds are the serious contenders for conventional materials used in photovoltaic devices that will provide a bright future for solar cell industry. Therefore, preparing a comprehensive insight about their properties is necessary. In this regard, the electronic and optical studies of two important perovskite compound CsPbI3 and CH3NH3PbI3 in the cubic phase are performed by ?rst- principle method in Density Function Theory (DFT), using several approximations namely GGA, t-mbj and other types of t-mbj approximation with the tuned coef?cient including k-mbj and new mbj approximations. In addition to utilizing di?erent approximations, the e?ect of spin orbit coupling which is critical in these compounds, is evaluated in all of them to obtain realistic results. The band gaps calculated within new mbj approximation through spin orbit coupling are 1.34 eV and 1.49 eV for CsPbI3 and CH3NH3PbI3, respectively that unlike other DFT-based electronic calculations are in agreement with experimental results. Values of estimated e?ective masses of carriers represent lighter carriers for CH3NH3PbI3 in comparison to CsPbI3. Optical calculations of frequency dependent dielectric function con?rm non isotropic property in organic- inorganic perovskite CH3NH3PbI3 and estimate value of static refraction index equal to 2.47 which is in agreement with experimental measurements.
关键词： DFT,Optical properties,CsPbI3,CH3NH3PbI3,Photovoltaic applications
更新于2025-09-16 10:30:52
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Effect of incorporating different polyanilinea??surface modified nanosilica content into polyurethanea??based quasia??solida??state electrolyte for dyea??sensitized solar cells
摘要： Polyaniline-surface modified nanosilica (S-PANi) was incorporated into polyurethane (PU) to form a polymer matrix able to entrap liquid electrolyte and to function as a quasi-solid state electrolyte (QSE) in dye-sensitized solar cells (DSSCs). Nanosilica was first synthesized via sol–gel technique and was post modified with aniline to form S-PANi. The effects of introducing different S-PANi content (5, 10, 15, and 20 wt%) on the nanoparticle distribution, surface morphology, surface porosity, thermal stability, and the structure of the PU matrix were analyzed using transmitted and reflected light microscopes, TGA and X-ray powder diffraction. Additionally, polymer matrix absorptivity, conductivity, and ion diffusion of the formulated QSEs were investigated by using a digital analytical balance, the AC impedance method, and cyclic voltammetry. Lastly, all of the formulated quasi-solid-state electrolytes were applied for use in DSSCs wherein their charge recombination, photovoltaic performance, and lifespan were measured. The quasi-solid-state electrolyte based on 15 wt% S-PANi (PU-15%S-PANi) exhibited the highest light-to-energy conversion efficiency, namely 3.17%, with an open circuit voltage of 708 mV, a short circuit current of 4.13 mA cm?2, and a fill factor of 0.65.
关键词： films,swelling,nanoparticles,nanowires and nanocrystals,optical and photovoltaic applications,polyurethane
更新于2025-09-16 10:30:52
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A Single-switch Single-magnetic Core High Conversion Ratio Converter with Low Input Current Ripple and Wide Soft-switching Range for Photovoltaic Applications
摘要： In this paper, a novel high conversion ratio DC-DC converter suitable for photovoltaic applications is presented. Utilizing single-switch and single-magnetic core, low ripple input current and low voltage stress across the semiconductors are the major advantages of the proposed converter. In order to provide soft-switching condition for the converter switch at a wide range of output power, a passive lossless snubber is employed. The presented converter is adequate for photovoltaic applications due to mentioned properties. Operating principles are analyzed and design considerations are provided. In order to validate the theoretical analysis, a prototype of the proposed converter is implemented and the experimental results are exhibited.
关键词： single-switch,single-magnetic core,lossless passive snubber,High conversion ratio,soft-switching,photovoltaic applications
更新于2025-09-12 10:27:22
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Development of Photovoltaic Module with Fabricated and Evaluated Novel Backsheet-Based Biocomposite Materials
摘要： Photovoltaic backsheets have considerable impact on the collective performance of solar cells. Material components should withstand certain temperatures and loads while maintaining high thermal stability under various weather conditions. Solar modules must demonstrate increased reliability, adequate performance, safety, and durability throughout the course of their lifetime. This work presents a novel solar module. The module consists of an innovative polyvinylidene fluoride-short sugar palm fiber (PVDF-SSPF) composite backsheet within its structure. It was electrically and thermally evaluated. The current-voltage characteristics (I-V) were obtained using the solar module analyzer, PROVA 210PV. A thermal evaluation was accomplished using a temperature device, SDL200. The thermal test consisted of two different assessments. The first targeted the surface and backsheet of the developed module to correlate their performance from within. The second assessment compared the thermal performance of the fabricated backsheet with the conventional one. Both tests were combined into a heatmap analysis to further understand the thermal performance. Results revealed that the developed module exhibited reasonable electrical efficiency, achieving appropriate and balanced I-V curves. PVDF-SSPF backsheets proved to be thermally stable by displaying less heat absorbance and better temperature shifts. Additional research efforts are highly encouraged to investigate other characteristics. To enhance performance, further analyses are needed such as the damp heat analysis, accelerated aging analysis, and heat dissipation phenomena.
关键词： photovoltaic applications,electrical and thermal performances,novel backsheets,solar modules
更新于2025-09-12 10:27:22
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Mechanoperovskites for Photovoltaic Applications: Preparation, Characterization, and Device Fabrication
摘要： Hybrid organic?inorganic metal halide perovskites (MHPs) have emerged as excellent absorber materials for next generation solar cells owing to their simple solution-processed synthesis and high efficiency. This breakthrough in photovoltaics along with an accompanying impact in light-emitting applications prompted a renaissance of interest in the broad family of MHPs. Notably, the optoelectronic properties and the photovoltaic parameters of MHPs are highly sensitive to the adopted synthetic strategy. The preparation of MHPs has commonly relied on solution-based methods requiring elevated temperatures for homogeneity of reaction mixtures. While the solution-based approach is relatively versatile, it faces challenges such as limitations in compositional engineering of MHPs or their long-term storage among others. Therefore, there is a continuous great challenge to develop efficient synthetic strategies affording various high-quality MHP materials for numerous technological optoelectronic applications.
关键词： Preparation,Characterization,Device Fabrication,Photovoltaic Applications,Mechanoperovskites
更新于2025-09-12 10:27:22