scholarly journals Efficient Emission in Halide Layered Double Perovskites: The Role of Sb3+ Substitution in Cs4Cd1–xMnxBi2Cl12 Phosphors

2020 ◽  
Author(s):  
Brenda Vargas ◽  
Eduardo Coutiño-Gonzalez ◽  
Oscar Ovalle-Encinia ◽  
Citlali Sánchez-Aké ◽  
Diego Solis-Ibarra
Keyword(s):  
Optoelectronic Properties ◽  
Double Perovskites ◽  
Spin Orbit Coupling ◽  
Fixed Amount ◽  
Electronic Delocalization ◽  
The Subject ◽  
Halide Perovskites ◽  
Pl Emission ◽  
Intense Research

Layered halide perovskites and double perovskites optoelectronic properties have recently been the subject of intense research. Layered double perovskites represent the merging of both worlds, and as such, have the potential to further expand the already vast space of optoelectronic properties and applications of halide perovskites. Despite having more than 40 known members, to date, only the <111>-oriented layered double perovskites: Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<sub>x</sub><b>Bi</b><sub>2</sub>Cl<sub>12</sub>, have shown efficient photoluminescence (PL). In this work, we replaced Bi with Sb to further investigate the electronic structure and PL properties of these materials, resulting in two new families of layered inorganic perovskites alloys with full solubility. The first family, Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<b>Sb</b><sub>2</sub>Cl<sub>12</sub>, exhibits a PL emission at 605 nm ascribed to Mn<sup>2+</sup> centers in octahedral coordination, and a maximum photoluminescence quantum yield PLQY of 28.5%. The second family of alloys, also with full solubility, Cs<sub>4</sub>Cd<sub>0.8</sub>Mn<sub>0.2</sub>(Sb<sub>1</sub>–<sub>y</sub>Bi<sub>y</sub>)<sub>2</sub>Cl<sub>12</sub>, contains a fixed amount of Mn<sup>2+</sup> and Cd<sup>2+</sup> cations but different concentrations of the trivalent metals. This variability allows the tuning of the PL emission from 603 nm to 614 nm. We show that the decreased efficiency of the Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<sub>x</sub>Sb<sub>2</sub>Cl<sub>12</sub>family compared to Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<sub>x</sub><b>Bi</b><sub>2</sub>Cl<sub>12</sub>, is mostly due to a decreased spin-orbit coupling in Sb and the subsequent increased electronic delocalization compared to the Bi alloys, reducing the energy transfer to Mn<sup>2+</sup> centers. This work lays out a roadmap to understand and achieve high photoluminescence efficiencies in layered double perovskites.<p></p>

scholarly journals Efficient Emission in Halide Layered Double Perovskites: The Role of Sb3+ Substitution in Cs4Cd1–xMnxBi2Cl12 Phosphors

2020 ◽  
Author(s):  
Brenda Vargas ◽  
Eduardo Coutiño-Gonzalez ◽  
Oscar Ovalle-Encinia ◽  
Citlali Sánchez-Aké ◽  
Diego Solis-Ibarra
Keyword(s):  
Optoelectronic Properties ◽  
Double Perovskites ◽  
Spin Orbit Coupling ◽  
Fixed Amount ◽  
Electronic Delocalization ◽  
The Subject ◽  
Halide Perovskites ◽  
Pl Emission ◽  
Intense Research

Layered halide perovskites and double perovskites optoelectronic properties have recently been the subject of intense research. Layered double perovskites represent the merging of both worlds, and as such, have the potential to further expand the already vast space of optoelectronic properties and applications of halide perovskites. Despite having more than 40 known members, to date, only the <111>-oriented layered double perovskites: Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<sub>x</sub><b>Bi</b><sub>2</sub>Cl<sub>12</sub>, have shown efficient photoluminescence (PL). In this work, we replaced Bi with Sb to further investigate the electronic structure and PL properties of these materials, resulting in two new families of layered inorganic perovskites alloys with full solubility. The first family, Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<b>Sb</b><sub>2</sub>Cl<sub>12</sub>, exhibits a PL emission at 605 nm ascribed to Mn<sup>2+</sup> centers in octahedral coordination, and a maximum photoluminescence quantum yield PLQY of 28.5%. The second family of alloys, also with full solubility, Cs<sub>4</sub>Cd<sub>0.8</sub>Mn<sub>0.2</sub>(Sb<sub>1</sub>–<sub>y</sub>Bi<sub>y</sub>)<sub>2</sub>Cl<sub>12</sub>, contains a fixed amount of Mn<sup>2+</sup> and Cd<sup>2+</sup> cations but different concentrations of the trivalent metals. This variability allows the tuning of the PL emission from 603 nm to 614 nm. We show that the decreased efficiency of the Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<sub>x</sub>Sb<sub>2</sub>Cl<sub>12</sub>family compared to Cs<sub>4</sub>Cd<sub>1</sub>–<sub>x</sub>Mn<sub>x</sub><b>Bi</b><sub>2</sub>Cl<sub>12</sub>, is mostly due to a decreased spin-orbit coupling in Sb and the subsequent increased electronic delocalization compared to the Bi alloys, reducing the energy transfer to Mn<sup>2+</sup> centers. This work lays out a roadmap to understand and achieve high photoluminescence efficiencies in layered double perovskites.<p></p>

scholarly journals Role of Lead Vacancies for Optoelectronic Properties of Lead-Halide Perovskites

2017 ◽  
Vol 122 (10) ◽  
pp. 5216-5226 ◽  
Author(s):  
Dayton J. Vogel ◽  
Talgat M. Inerbaev ◽  
Dmitri S. Kilin
Keyword(s):  
Optoelectronic Properties ◽  
Halide Perovskites ◽  
Lead Halide

scholarly journals Recent Advancements in Crystalline Pb-Free Halide Double Perovskites

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 62 ◽  
Author(s):  
Muhammad Usman ◽  
Qingfeng Yan
Keyword(s):  
Large Scale ◽  
Optoelectronic Properties ◽  
Double Perovskites ◽  
Ambient Conditions ◽  
Photoelectric Properties ◽  
Potential Alternative ◽  
High Carrier Mobility ◽  
Halide Perovskites ◽  
Synthesis Composition ◽  
Lead Halide

Lead halide perovskites have gained more and more attention because of their ease of synthesis and excellent photoelectric properties including a large absorption coefficient, long carrier lifetime, long carrier diffusion length, and high carrier mobility. However, their toxicity, instability, and phase degradation in ambient environments impede their large-scale applications. To address these concerns, it is desirable to find stable alternative halide perovskites without toxicity and with comparable optoelectronic properties to lead-based perovskites. Over the years, a considerable number of lead-free halide perovskites have been added to this family of materials, including A2B’B’’X6, A2BX6, and A3B2X9 type perovskites. Among these, double perovskites with the general formula A2B’B’’X6 are deemed to be a potential alternative to lead halide perovskites as they possess good stability under ambient conditions and excellent optoelectronic properties. In this review, recent progress in exploring Pb-free halide double perovskites is highlighted. The synthesis, composition-tuning, physical properties, and applications of representative 3D, 2D, and nanocrystal A2B’B’’X6 double perovskites are introduced. In addition, perspectives about current challenges and solutions in this field are also provided.

scholarly journals Symbiotic bacteria on the cuticle of the leaf-cutting ant Acromyrmex subterraneus subterraneus protect workers from attack by entomopathogenic fungi

2011 ◽  
Vol 8 (3) ◽  
pp. 461-464 ◽  
Author(s):  
Thalles C. Mattoso ◽  
Denise D. O. Moreira ◽  
Richard I. Samuels
Keyword(s):  
Direct Evidence ◽  
Fungus Garden ◽  
Defensive Strategy ◽  
Fungal Entomopathogen ◽  
Leaf Cutting ◽  
The Subject ◽  
Anti Fungal ◽  
First Time ◽  
Intense Research

Although only discovered in 1999, the symbiotic filamentous actinobacteria present on the integument of certain species of leaf-cutting ants have been the subject of intense research. These bacteria have been shown to specifically suppress fungal garden parasites by secretion of antibiotics. However, more recently, a wider role for these bacteria has been suggested from research revealing their generalist anti-fungal activity. Here we show, for the first time, evidence for a role of these bacteria in the defence of young worker ants against a fungal entomopathogen. Experimental removal of the bacterial bio-film using an antibiotic resulted in a significant increase in susceptibility of worker ants to infection by the entomopathogenic fungus Metarhizium anisopliae . This is the first direct evidence for the advantage of maintaining a bacterial bio-film on the cuticle as a defensive strategy of the ants themselves and not exclusively for protection of the fungus garden.

scholarly journals The Role of Dimensionality on the Optoelectronic Properties of Oxide and Halide Perovskites, and their Halide Derivatives

2021 ◽  
pp. 2100499
Author(s):  
Robert L. Z. Hoye ◽  
Juanita Hidalgo ◽  
Robert A. Jagt ◽  
Juan‐Pablo Correa‐Baena ◽  
Thomas Fix ◽  
...  
Keyword(s):  
Optoelectronic Properties ◽  
Halide Perovskites

scholarly journals Lead-free metal-halide double perovskites: from optoelectronic properties to applications

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mehri Ghasemi ◽  
Mengmeng Hao ◽  
Mu Xiao ◽  
Peng Chen ◽  
Dongxu He ◽  
...  
Keyword(s):  
High Efficiency ◽  
Radiation Detectors ◽  
Optoelectronic Properties ◽  
Metal Halide ◽  
Material Structure ◽  
Double Perovskites ◽  
Light Emitting ◽  
High Efficiency Solar Cells ◽  
Halide Perovskites ◽  
Function Relationship

AbstractLead (Pb) halide perovskites have witnessed highly promising achievements for high-efficiency solar cells, light-emitting diodes (LEDs), and photo/radiation detectors due to their exceptional optoelectronic properties. However, compound stability and Pb toxicity are still two main obstacles towards the commercialization of halide perovskite-based devices. Therefore, it is of substantial interest to search for non-toxic candidates with comparable photophysical characteristics. Metal-halide double perovskites (MHDPs), A2BBʹX6, are recently booming as promising alternatives for Pb-based halide-perovskites for their non-toxicity and significantly enhanced chemical and thermodynamic stability. Moreover, this family exhibits rich combinatorial chemistry with tuneable optoelectronic properties and thus a great potential for a broad range of optoelectronic/electronic applications. Herein, we present a comprehensive review of the MHDPs synthesized so far, and classified by their optical and electronic properties. We systematically generalize their electronic structure by both theoretical and experimental efforts to prospect the relevant optoelectronic properties required by different applications. The progress of the materials in various applications is explicated in view of the material structure-function relationship. Finally, a perspective outlook to improve the physical and optoelectronic properties of the materials is proposed aiming at fostering their future development and applications.

scholarly journals Use of the Codon Table to Quantify the Evolutionary Role of Random Mutations

Algorithms ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 270
Author(s):  
Mihaly Mezei
Keyword(s):  
Amino Acid ◽  
Codon Usage ◽  
Evolutionary Tree ◽  
Sequence Alignments ◽  
Amino Acid Mutation ◽  
Amino Acid Similarity ◽  
The Subject ◽  
Evolutionary Role ◽  
Intense Research

The various biases affecting RNA mutations during evolution is the subject of intense research, leaving the extent of the role of random mutations undefined. To remedy this lacuna, using the codon table, the number of codons representing each amino acid was correlated with the amino acid frequencies in different branches of the evolutionary tree. The correlations were seen to increase as evolution progressed. Furthermore, the number of RNA mutations that resulted in a given amino acid mutation were found to be correlated with several widely used amino acid similarity tables (used in sequence alignments). These correlations were seen to increase when the observed codon usage was factored in.

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

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