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Strategies to Achieve High Performance Piezoelectric Nanogenerators
摘要： Piezoelectric nanogenerators have attracted much attention in the past decade. In this study, the development of piezoelectric nanogenerators and their progress toward high power generation is discussed. The characteristics and application range of numerous types of piezoelectric nanogenerators are also considered. In addition, several strategies that may improve the performance of piezoelectric nanogenerators are summarized. Here, we compare the open circuit voltages and short circuit currents of various piezoelectric nanogenerators under different factors, and the current problems of piezoelectric nanogenerators are also discussed. Finally, the future prospects and directions of piezoelectric nanogenerators are predicted. Future studies should be focused on the production of high-performance materials, the establishment of working principle and simulation model, the integration of nanogenerator, and the design of the energy harvesting circuit. Hence, it is emergency to search for functional materials with high piezoelectricity and further improve the electromechanical properties of existing piezoelectric materials. Moreover, further research is needed to increase the stability and flexibility of composite materials, to develop wearable and embedded flexible functional devices based on the biocompatibility of inorganic nanoparticles, and to supply power for microelectronic systems.
关键词： BaTiO3,Piezoelectric nanogenerators,Composite thin film materials,PVDF,Chemical doping,Nanostructure
更新于2025-09-23 15:21:01
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Thin-Film Solar Cells
摘要： Copper-indium-gallium-diselenide (CIGS) thin-film solar cells suffer from high recombination losses at the back contact and parasitic absorption in the front-contact layers. Dielectric passivation layers overcome these limitations and enable an efficient control over interface recombination, which becomes increasingly relevant as thin-film solar cells increase in efficiency and become thinner to reduce the consumption of precious resources. We present the optoelectronic and chemical interface properties of oxide-based passivation layers deposited by atomic layer deposition on CIGS. A suitable postdeposition annealing removes detrimental interface defects and leads to restructuring and oxidation of the CIGS surface. The optoelectronic interface properties are very similar for different passivation approaches, demonstrating that an efficient suppression of interface states is possible independent of the metal used in the passivating oxide. If aluminum oxide (Al2O3) is used as the passivation layer we confirm an additional field-effect passivation due to interface charges, resulting in an efficient interface passivation superior to that of a state-of-the-art cadmium-sulfide (CdS) buffer layer. Based on this chemical interface model we present a full-area rear-interface passivation layer without any contact patterning, resulting in a 1% absolute efficiency gain compared to a standard molybdenum back contact.
关键词： CIGS,CdS,atomic layer deposition,oxidation,thin-film solar cells,recombination losses,Al2O3,interface passivation
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Optoelectronic Characterization of Emerging Solar Absorber Cu <sub/>3</sub> AsS <sub/>4</sub>
摘要： Enargite Cu3AsS4 is a promising absorber for thin-film solar cells but little is known about its optoelectronic properties. Here, we present photoluminescence (PL) spectroscopy, time-resolved terahertz spectroscopy (TRTS), time-resolved photoluminescence (TRPL) spectroscopy, and cyclic voltammetry (CV) measurements of enargite thin films. The results indicate promising defect characteristics with minority carrier lifetimes on the order of ns, and band alignments suggest that buffer layers besides CdS must be developed to achieve high efficiency Cu3AsS4 solar cells.
关键词： photovoltaic cells,copper compounds,thin film devices,semiconductor materials,nanocrystals
更新于2025-09-23 15:21:01
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Molecular Simulations of Laser Spike Annealing of Block-Copolymer Lamellar Thin-Films
摘要： We use molecular dynamic simulations to study the phase behavior of a coarse-grained lamella-forming A-b-B di-block copolymer under thin-film soft confinement for different heating cycle lengths, film thicknesses, and substrate-polymer affinities. This model describes the effect on thin-film morphology with a free surface (air-polymer interface) and a solid substrate. Our simulation results were first validated by showing that they capture changes for the order-disorder transition temperature with annealing conditions consistent with those found in laser spike annealing experiments, when the vertical lamella phase formed on neutral substrates. In addition, simulations with a substrate selective for a particular block revealed the formation of other phases including a mixed vertical-horizontal lamella and a metastable island phase having horizontal but incomplete lamella layers. The nanoscale roughness features of this island phase, and hence its surface wettability, can be tuned with suitable choices of chemistry and annealing conditions.
关键词： thin-film,nanoscale roughness,order-disorder transition,phase behavior,laser spike annealing,molecular dynamic simulations,block copolymer
更新于2025-09-23 15:21:01
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Transparent Thin-Film Silicon Solar Cells for Indoor Light Harvesting with Conversion Efficiencies of 36% without Photo-degradation
摘要： With the development of the Internet of Things (IoT), indoor photovoltaics are attracting considerable interest owing to their potential to benefit various IoT-related fields. Therefore, this study investigates the use of transparent hydrogenated amorphous silicon (a-Si:H) solar cells for a broad range of applications, including indoor light harvesting. High gap triple-layers were employed in the a-Si:H solar cells to obtain a high shunt resistance and high short-circuit current, JSC, and open-circuit voltage, VOC, under indoor illumination. Additionally, multiple color-adjusting layers were added without noticeable costs to the conversion efficiency. The maximum efficiency of 36.0% was obtained at a transmittance of 20.44% under white LED light (3,000 lx and 0.92 mW cm-2). Furthermore, the fabricated transparent solar cells show excellent long-term performance, sustaining over 99% of original efficiency under continuous indoor light illumination for 200 h. These cells could accelerate the progress of energy harvesting in IoT applications and facilitate the construction of integrated photovoltaics.
关键词： amorphous silicon solar cells,thin film silicon solar cells,transparent solar cells,indoor photovoltaics,colored solar cells
更新于2025-09-23 15:21:01
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Design and Optimization Methodology of Coplanar Waveguide Test Structures for Dielectric Characterization of Thin Films
摘要： This paper describes an accurate design method of coplanar waveguide (CPW) test structures on characterizing dielectric properties of thin films with arbitrary thickness. Current CPW measurement method has difficulty in providing accurate dielectric properties of films with extremely small thickness. To address this issue, an optimized algorithm is presented to generate proper geometric parameters of CPW test structures for films with different thickness. To validate the accuracy of the proposed design methodology, various test cases of CPW structures with different dimensions have been designed and implemented, the extracted dielectric properties (e.g., dielectric constant and loss tangent) from the S-parameters of the different test cases are compared to the benchmark results simulated by accurate electromagnetic tool Ansys HFSS. It demonstrates the efficacy of the proposed optimized method on quickly producing correct dimensions of CPW test lines for accurate properties characterization of thin films.
关键词： Dielectric properties,Thin film,Coplanar waveguide test structure,Optimization method
更新于2025-09-23 15:21:01
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Evaluation of ion bombardment in DC magnetron sputtering DC
摘要： Momentum of ion bombardment in sputtering deposition process, which strongly depends on internal stress of thin film, has been evaluated regarding to a new parameter Pi we previously proposed for fine-tuning of mechanical, optical, electrical and magnetic properties. In this study, we demonstrate to estimate the Pi defined as (i/a) p, where i the ion flux, a the atom flux and p the ion’s momentum, by means of Langmuir probe and multi-grid analyzer in a function of negative bias voltage applied on substrates Vsub. As a result, it was found that the Pi was roughly proportional to Vsub except on lower voltage than 30 V. This indicates that the Pi should be measured plasma-diagnostically under incident ion energy as low as plasma potential.
关键词： Sputter,Thin film,Ion bombardment,Intrinsic stress,Plasma
更新于2025-09-23 15:21:01
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Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings
摘要： Today’s advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facades—jointly known as “glazings”—since current practices often lead to huge energy expenditures related to excessive inflow or outflow of energy which need to be balanced by energy-intensive cooling or heating. This review article outlines recent progress in thermochromics, i.e., it deals with materials whose optical properties are strongly dependent on temperature. In particular, we discuss oxide-based thin surface coatings (thin films) and nanoparticle composites which can be deposited onto glass and are able to regulate the throughput of solar energy while the luminous (visible) properties remain more or less unaltered. Another implementation embodies lamination materials incorporating thermochromic (TC) nanoparticles. The thin films and nanocomposites are based on vanadium dioxide (VO2), which is able to change its properties within a narrow temperature range in the vicinity of room temperature and either reflects or absorbs infrared light at elevated temperatures, whereas the reflectance or absorptance is much smaller at lower temperatures. The review outlines the state of the art for these thin films and nanocomposites with particular attention to recent developments that have taken place in laboratories worldwide. Specifically, we first set the scene by discussing environmental challenges and their relationship with TC glazings. Then enters VO2 and we present its key properties in thin-film form and as nanoparticles. The next part of the article gives perspectives on the manufacturing of these films and particles. We point out that the properties of pure VO2 may not be fully adequate for buildings and we elaborate how additives, antireflection layers, nanostructuring and protective over-coatings can be employed to yield improved performance and durability that make TC glazings of considerable interest for building-related applications. Finally, we briefly describe recent developments towards TC light scattering and draw some final conclusions.
关键词： thermochromism,vanadium dioxide,thin film,energy-efficient glazing,coating,sputter deposition,nanoparticle
更新于2025-09-23 15:21:01
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Lithium-Doping Effects in Cu(In,Ga)Se2 Thin-Film and Photovoltaic Properties
摘要： The beneficial effects of heavy alkali-metals such as K, Rb, and Cs in enhancing Cu(In,Ga)Se2 (CIGS) photovoltaic efficiencies are widely known, though the detailed mechanism is still open for discussion. In the present work, the effects of the lightest alkali-metal, Li, on CIGS thin-film and device properties are focused upon and compared to the effects of heavy alkali-metals. To date, the beneficial effects of elemental Li on Cu2ZnSnS4 (CZTS) photovoltaic devices in enhancing efficiencies have been reported in the literature. On the other hand, it is shown in the present work that the beneficial effects of Li on CIGS are not so significant. In contrast to the effects of Na or Rb in enhancing CIGS (112) growth orientation, Li was revealed not to affect CIGS growth orientation. The most distinctive feature observed between Li and other alkali-metals was the elemental depth profile in CIGS films. Namely, Na and heavier alkali-metals show a concentration peak near the surface region (relatively Cu-poor region) of CIGS films, whereas elemental Li showed no such trend, suggesting that Li has no significant effect on CIGS surface modification. Nonetheless, Li was found to have some effect in enhancing the PL peak intensity and photovoltaic performance of CIGS, though the effect is relatively small in comparison to that obtained with other alkali-metals.
关键词： CIGS,lithium,thin-film solar cell,rubidium,chalcogenide,chalcopyrite,alkali-metal
更新于2025-09-23 15:21:01
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The impacts of LPCVD wrap-around on the performance of n-type tunnel oxide passivated contact c-Si solar cell
摘要： In this paper, Tunnel Oxide Passivated Contact (TOPCon) silicon solar cells with the industrial area (244.32cm2) are fabricated on N-type silicon substrates. Both the ultra-thin tunnel oxide layer and phosphorus doped polycrystalline silicon (polysilicon) thin film are prepared by the LPCVD system. The wrap-around of polysilicon is observed on the surface of borosilicate glass (BSG). The polysilicon wrap-around can form a leakage current path, thus degrades the shunt resistance of solar cells, and leads to the degradation of solar cell efficiency. Different methods are adopted to treat the polysilicon wrap-around and improve shunt resistance of solar cells. The experimental results indicate that a chemical etching method can effectively solve the problem of polysilicon wrap-around and improve the performance of solar cells. Finally, a conversion efficiency of 22.81% has been achieved by our bifacial TOPCon solar cells, with Voc of 702.6 mV, Jsc of 39.78 mA/cm2 and FF of 81.62 %.
关键词： LPCVD,wrap-around,Tunnel oxide passivated contact,polycrystalline silicon thin film
更新于2025-09-23 15:21:01