Organometal Halide Perovskites Thin Film and Their Impact on the Efficiency of Perovskite Solar Cells

The organometal halide perovskite solar cells (PSCs) have attracted attention and achieved efficiencies compared with traditional solar cells. There are several ways to develop perovskite solar cells like effect of moisture, degradation, and understanding the reason for instability of perovskite. In this chapter, we are specified how to make coating and film fabrication are affected by the existing methods. Improvement in the photovoltaic performance of PSCs can be achieved by enhanced processing technique. These techniques include the spin-coating PbI2 solution controlling the substrate temperature and crystal quality of the morphology for perovskite films. There is no doubt that film coating indicates that the crystallization and morphology of perovskite films affect the absorption intensity and obviously influence the short-circuit current density. This study points out an enhancement of the stability of perovskite films and solar cells by reducing residual strains in perovskite films

Principal Perceptions of District Support in Oklahoma: What They Get, What They Want, and How It Affects Their Psychological Needs

The purpose of this study is to explore the relationship between principals’ basic psychological needs and the district-level factors that support them. Evidence from the past thirty years of educational research has pointed to school principals as influential in improving school outcomes. In addition to their traditional managerial roles, principals are now expected, among other things, to develop a shared vision of high achievement, cultivate a strong culture, develop and recruit teaching talent, and most importantly, to improve teaching and learning. Because of this, the principalship has continued to evolve into a role of ever-increasing complexity that has been shown to carry extremely high levels of pressure, stress, and burnout. While there is a growing body of literature on what school districts can do to support principals’ capacity for instructional leadership and school improvement, little attention has been given to understanding what types of support principals report needing from the district office in order to meet their psychological needs. For principals to carry out the challenging and complex work before them, there must be a greater understanding of which district-imposed conditions support their motivation to engage in that work. Using self-determination theory, a survey of 187 elementary and secondary principals across the state of Oklahoma was conducted to determine what principals in the State currently receive from their district offices, the relationship between those supports and principals’ psychological needs, and to identify the supports principals report to value and want from their district offices to better support them in their work. “Principals” was used to refer to both head principals and assistant principals. The study found that goal setting and instructional coherence (ß=.255), support for autonomy (ß=.295), and networking and collaboration opportunities (ß=.186) were supports provided by Oklahoma districts which had a positive correlation with principals’ basic psychological needs and its subscales. It also found that while the majority of school districts offer professional development and mentoring opportunities as supports for their principals, principals themselves place more value on autonomy supports and networking and collaboration opportunities. These results have implications for how districts should go about supporting their principals in their work and also build upon the theoretical and empirical knowledge related to district effectiveness and principal development

Controlling the Microstructure and Properties of Titanium Dioxide for Efficient Solar Cells

In this chapter, we review the controlling of the microstructures, the properties, and the different methods to obtain titanium dioxide and the application of these materials on solar cells. We will concentrate on the application of efficient solar cells including dye-sensitized solar cells (DSSCs). In the first section, we provide a background on energy, including its sources—photovoltaics and titanium dioxide—and the advantages of their application in solar cells. The second section outlines the different methods to obtain TiO2 nanoparticles. The shapes of titanium dioxide are explored in the third section. In the fourth section, we discuss the use and effect of the titanium dioxide in the efficient dye-sensitized solar cells, and the last section is a summary of the current state of the art and perspectives of titanium dioxide for efficient solar cells

Pathways Towards High-Stable, Low-Cost and Efficient Perovskite Solar Cells

The power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have been reached the initial value when they emerged as dye sensitized solar cell (DSSC) in 2012. Immediately, the interests were drawn in this field worldwide. The researchers have improved the efficiency of PSCs up-to 22%, which was originally started from its initial value of 3.8%, just in 7 years. The rendering of long‐term stabilization and effective cost have special importance for PSCs since the instability issue remained idle in spite of those recently increased efficiency values attained by various research groups. In this way, the better improvements of PSC may increase extraordinary exhibitions as compared to alternate solar cells like organic solar cell (OSC) or DSSC devices. This chapter begins with a general discussion on the requirement for an economical clean energy conversion device. In section 2, fundamental properties of PSC are fit together with their device architecture and working mechanism. In section 3 proceeds with a review on fundamental photovoltaic parameters joined by current-voltage hysteresis. Furthermore, the stability and cost issues will be discussed in Sections 4 and 5. In the end of this chapter, we are discussing the challenges and opportunities based on the chapter content

Mixed 2D-3D Halide Perovskite Solar Cells

The 3D-perovskite halides have gained a considerable reputation versus their counterpart semiconductor materials since they achieved a remarkable high-power conversion efficiency of 25.2% within a decade. Perovskite solar cells also have some problems as lattice degradation and sensitivity against moisture, oxygen, and strong irradiation. The perovskite instability is the drawback in front of this emerging technology towards mass production and commercialization. 2D-perovskites, with the general formula A2Bn − 1MnX3n + 1, have been recently introduced to overcome some of the drawbacks of the stability of 3D-perovskites; however, this is at the expense of sacrificing a part of the power conversion efficiency. Mixed 2D/3D perovskites could solve this dilemma towards the way to high stability-efficiency perovskites. The research is expected to obtain highly stable and efficient mixed 2D/3D perovskite solar cells in the few coming years. This chapter reviews 2D-perovskites’ achieved progress, highlighting their properties, current trends, challenges, and future prospects

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Bench blast modeling: Consequences of crushed zone, wave front shape, and radial cracks.

A geometrical model for the rock crushed zone around a cylindrical charge is developed. The model is used to obtain empirical relationships between the scaled crushed zone diameter and some dimensionless ratios of explosive and rock properties. The ratios are velocity ratio, characteristic impedance ratio, medium stress ratio, and detonation pressure ratio. The empirical relations for granite, salt, and limestone in combination with a variety of explosives show that the scaled crushed zone diameter increases at a decreasing rate with increasing dimensionless ratios. The shape of the wave fronts around a cylindrical charge detonating in rock has been constructed for velocity ratios ranging from infinity to less than one. The shape of the wave front is not planar in the range of dimensions used in full scale bench blasting. The shape of the wave front is cylindrical in the middle and spherical at the top and bottom for infinite velocity ratio; sphero-conical for velocity ratios greater than one; spherical for velocity ratios ≤ 1. Quasi-static finite element models for a blasthole in a full scale bench blasting are analyzed using a 2-D finite element program written by the author. The models include a model neglecting radial cracks, models considering pressurized and non-pressurized radial cracks around the blasthole, and a model using an equivalent cavity to replace the pressurized radial cracks. Displacement fields, stress fields, and strain energy density distribution are studied. The analyses show that including radial cracks increases the levels of the strain energy density contours and the magnitudes of the displacement and stress fields several fold. The equivalent cavity gives much lower levels of strain energy contours and gives lower displacement and stress field magnitudes than those produced by the pressurized radial cracks. The scaled areas of the strain energy density contours increase at a decreasing rate with increasing the blasthole internal pressure and with increasing the ratio of the compressive strength to the tensile strength. These contour areas decrease at a decreasing rate with increasing tensile strength

医薬品応用を指向した新規バイオミメティック分子の設計とその評価

Stereochemistry dramatically impacts the biological activity of various drugs. In the present report, we investigated the role of stereochemistry of ceramide and its analogues in inducing the release of exosomes, a type of extracellular vesicles, from neuronal cells, with a potential benefit in improving the clearance of Amyloid-³ (A³), an agent of Alzheimer9s disease. A library of diverse ceramide analogues was synthesized with the purpose of varying stereochemistry (DE, LT, LE, DT) and hydrophobic tail length (6, 16, 18, 24). The exosome levels were quantified using TIM4-based exosome ELISA after the concentration of the conditioned medium by centrifugal filter devices. The results revealed a pivotal role of stereochemistry in determining the biological activity of ceramide and its analogs, with the superiority of those based on DE and DT stereochemistry with C16 and C18 tails, which demonstrated a significantly higher exosome release, without a significant change in the particle size of the released exosomes. In transwell experiments with A³-expressed neuronal cells and microglial cells, DE- and DT-ceramides with C16 and C18 tails significantly decreased extracellular A³ levels.The results reported here are promising in the design of non-classic therapies for the treatment of Alzheimer9s disease and other neurodegenerative disorders