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A young girl Yoona loves dinosaurs. She gets on an elevator to return books to the library, where she imagines each new person getting on the elevator to be a different dinosaur.
Book
Development of Induction Heating System Ensuring Increased Heating Efficiency of the Charge Material in a Forging
This study performs a complex analysis and review of the currently applied methods of inductively heating the charge material in hot die forging processes, as well as elaborates and verifies a more effective heating method. On this basis, a device for inductive heating using variable frequency inductors was designed and constructed, which made it possible to reduce the scale and decarburization with respect to the heater used so far. In the first place, the temperature distributions in the heater in the function of time were modeled with the use of the CEDRAT FLUX software. The aim of the research was to analyze the temperature gradient and value diversification on the surface and in the material core, as well as to determine the process stability. The following stage was designing and constructing a heater with an automatic system of loading and positioning of the charge on the exit, as well as with a possibility of working in a fully automated system adjusted to the work center. The last stage of investigations was the verification of the elaborated effective heating method on the basis of a short production series and a continuous work for the period of 8 h, both in the quantitative and qualitative aspect (reduced oxidation and decarburization as well as a gradient between the core and the surface). The obtained results confirm the effectiveness of the proposed solution referring to heating the charge material, especially in the aspect of stability and repeatability of the process, as well as a significant reduction in oxidation and decarburization of the material surface.
Journal Article
Validation of a Textile Material’s Electrostatic Characterization Device for Different Parameters and Their Effect on the Electrostatic Charge Generation
This research aims to validate an electrostatics characterization device to better understand the process of static charge generation in textile materials and to see how different factors affect it. This electrostatic device offers a variety of settings for controlling sample electrostatic activation and has a sample size range of up to one square meter. It can move in both horizontal and vertical directions in a controlled manner, providing a variety of possibilities for testing the effect of various movement features on electrostatic charge formation. Not only the textile polymer but also the motion characterizations influence the generation of electrostatic charges in textiles. The influence of frequency, pressure, dwell time between moves, test duration, effect of different sample sizes, and amplitude of movement on electrostatic charge generation was studied in greater detail. Two different parameters of the electrostatic waveform (peak voltage and peak-to-peak voltage) were investigated. The generation of electrostatic charges is proportional to the peak voltage and peak-to-peak voltage of the electrostatic waveform. Overall electrostatic charge generation increases with increasing frequency, stepping height, applied pressure at the same frequency, and sample size, but decreases with increasing dwell time between moves at the same frequency. The charge also increases with test duration until a saturation point is reached.
Journal Article
Recent progress in the development of high-efficiency inverted perovskite solar cells
Perovskite solar cells (PSCs) have attracted much attention due to their low-cost fabrication and high power conversion efficiency (PCE). However, the long-term stability issues of PSCs remain a significant bottleneck impeding their commercialization. Inverted PSCs with a p-i-n architecture are being actively researched due to their concurrent good stability and decent efficiency. In particular, the PCE of inverted PSCs has improved significantly in recent years and is now almost approaching that of n-i-p PSCs. This review summarizes recent progress in the development of high-efficiency inverted PSCs, including the development of perovskite compositions, fabrication methods, and counter electrode materials (CEMs). Notably, we highlight the development of charge transport materials (CTMs) and the effects of defect passivation strategies on the performance of inverted PSCs. Finally, we discuss the remaining issues and perspectives of high-efficiency inverted PSCs.
Inverted perovskite solar cells (PSCs) with a p-i-n architecture are being actively researched due to their concurrent good stability and decent efficiency. In particular, the power conversion efficiency (PCE) of inverted PSCs has seen clear improvement in recent years and is now almost approaching that of n-i-p PSCs. Here, we systematically review recent progress in the development of high-efficiency inverted PSCs, and highlight the development of charge transport materials and the effects of defect passivation strategies on the performance of inverted PSCs, with the aim of providing constructive suggestions for the future development of inverted PSCs.
Journal Article
Rapid advances enabling high-performance inverted perovskite solar cells
Perovskite solar cells (PSCs) that have a positive–intrinsic–negative (p–i–n, or often referred to as inverted) structure are becoming increasingly attractive for commercialization owing to their rapid increase in power conversion efficiency, easily scalable fabrication, reliable operation and compatibility with various perovskite-based tandem device configurations. Here, we review key material and device considerations for making highly efficient and stable p–i–n PSCs. First, we summarize key advances in charge transport materials, which were critical to the rapid power conversion efficiency progress. Second, we discuss promising perovskite compositions and fabrication methods. We highlight various additive engineering approaches to improve the perovskite layer as well as interface engineering strategies that target either the buried or top perovskite surface layer. Third, we review progress in tandem devices, focusing on optimization of the interconnection layer. Next, we summarize the status and strategies for improving p–i–n PSC stability, especially considering the challenges of outdoor applications. We also provide prospects for future research directions and challenges.
Inverted (p–i–n) perovskite solar cells are promising candidates for real-life applications. This Review discusses the current status of this technology, key strategies for stability and efficiency improvements — from the materials selection to interface engineering and device construction — and future outlooks.
Journal Article
Stability-limiting heterointerfaces of perovskite photovoltaics
Optoelectronic devices consist of heterointerfaces formed between dissimilar semiconducting materials. The relative energy-level alignment between contacting semiconductors determinately affects the heterointerface charge injection and extraction dynamics. For perovskite solar cells (PSCs), the heterointerface between the top perovskite surface and a charge-transporting material is often treated for defect passivation
1
–
4
to improve the PSC stability and performance. However, such surface treatments can also affect the heterointerface energetics
1
. Here we show that surface treatments may induce a negative work function shift (that is, more n-type), which activates halide migration to aggravate PSC instability. Therefore, despite the beneficial effects of surface passivation, this detrimental side effect limits the maximum stability improvement attainable for PSCs treated in this way. This trade-off between the beneficial and detrimental effects should guide further work on improving PSC stability via surface treatments.
Surface treatments for the passivation of defects in perovskite solar cells have a detrimental side effect that limits the maximum stability improvement.
Journal Article
Wurtzite and fluorite ferroelectric materials for electronic memory
Ferroelectric materials, the charge equivalent of magnets, have been the subject of continued research interest since their discovery more than 100 years ago. The spontaneous electric polarization in these crystals, which is non-volatile and programmable, is appealing for a range of information technologies. However, while magnets have found their way into various types of modern information technology hardware, applications of ferroelectric materials that use their ferroelectric properties are still limited. Recent advances in ferroelectric materials with wurtzite and fluorite structure have renewed enthusiasm and offered new opportunities for their deployment in commercial-scale devices in microelectronics hardware. This Review focuses on the most recent and emerging wurtzite-structured ferroelectric materials and emphasizes their applications in memory and storage-based microelectronic hardware. Relevant comparisons with existing fluorite-structured ferroelectric materials are made and a detailed outlook on ferroelectric materials and devices applications is provided.
This Review presents the most recent ferroelectric materials with wurtzite structure and emphasizes applications in memory and storage-based microelectronic hardware.
Journal Article
σ–σ Stacked supramolecular junctions
Intermolecular charge transport plays an essential role in organic electronic materials and biological systems. To date, experimental investigations of intermolecular charge transport in molecular materials and electronic devices have been restricted to conjugated systems in which π–π stacking interactions are involved. Herein we demonstrate that the σ–σ stacking interactions between neighbouring non-conjugated molecules offer an efficient pathway for charge transport through supramolecular junctions. The conductance of σ–σ stacked molecular junctions formed between two non-conjugated cyclohexanethiol or single-anchored adamantane molecules is comparable to that of π–π stacked molecular junctions formed between π-conjugated benzene rings. The current–voltage characteristics and flicker noise analysis demonstrate the existence of stacked molecular junctions formed between the electrode pairs and exhibit the characteristics of through-space charge transport. Density functional theory calculations combined with the non-equilibrium Green’s function method reveal that efficient charge transport occurs between two molecules configured with σ–σ stacking interactions.
Supramolecular interactions play an essential role in organic electronic materials and biological systems. Now, it has been demonstrated that the σ–σ stacking interactions between neighbouring non-conjugated molecules can offer an efficient pathway for charge transport through supramolecular junctions, which provides a new guideline for the design and fabrication of organic materials and devices.
Journal Article
Standardized measurement of dielectric materials’ intrinsic triboelectric charge density through the suppression of air breakdown
Triboelectric charge density and energy density are two crucial factors to assess the output capability of dielectric materials in a triboelectric nanogenerator (TENG). However, they are commonly limited by the breakdown effect, structural parameters, and environmental factors, failing to reflect the intrinsic triboelectric behavior of these materials. Moreover, a standardized strategy for quantifying their maximum values is needed. Here, by circumventing these limitations, we propose a standardized strategy employing a contact-separation TENG for assessing a dielectric material’s maximum triboelectric charge and energy densities based on both theoretical analyses and experimental results. We find that a material’s vacuum triboelectric charge density can be far higher than previously reported values, reaching a record-high of 1250 µC m
−2
between polyvinyl chloride and copper. More importantly, the obtained values for a dielectric material through this method represent its intrinsic properties and correlates with its work function. This study provides a fundamental methodology for quantifying the triboelectric capability of dielectric materials and further highlights TENG’s promising applications for energy harvesting.
Determining the triboelectric charge and energy density of dielectric materials is generally limited by many factors, failing to reflect their intrinsic behaviour. Here, a standardized strategy is proposed employing contact-separation TENG and supressing air-breakdown to assess max triboelectric charge and energy densities leading to an updated triboelectric series.
Journal Article
Recent progress in perovskite solar cells: material science
Perovskite solar cells represent a promising third-generation photovoltaic technology with low fabrication cost and high power conversion efficiency. In light of the rapid development of perovskite materials and devices, a systematic survey on the latest advancements covering a broad range of related work is urgently needed. This review summarizes the recent major advances in the research of perovskite solar cells from a material science perspective. The discussed topics include the devices based on different type of perovskites (organic-inorganic hybrid, all-inorganic, and lead-free perovskite and perovskite quantum dots), the properties of perovskite defects, different type of charge transport materials (organic, polymeric, and inorganic hole transport materials and inorganic and organic electron transport materials), counter electrodes, and interfacial materials used to improve the efficiency and stability of devices. Most discussions focus on the key progresses reported within the recent five years. Meanwhile, the major issues limiting the production of perovskite solar cells and the prospects for the future development of related materials are discussed.
Journal Article