scholarly journals Electron Density and Its Relation with Electronic and Optical Properties in 2D Mo/W Dichalcogenides

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2221
Author(s):  
Pingping Jiang ◽  
Marie-Christine Record ◽  
Pascal Boulet
Keyword(s):  
Optical Properties ◽  
Lattice Mismatch ◽  
Compressive Strain ◽  
Interatomic Interaction ◽  
Structure Property ◽  
Electronic And Optical Properties ◽  
Cubic Equation ◽  
Structure Property Relationships ◽  
Stacking Order ◽  
Structures And Properties

Two-dimensional MX2 (M = Mo, W; X = S, Se, Te) homo- and heterostructures have attracted extensive attention in electronics and optoelectronics due to their unique structures and properties. In this work, the layer-dependent electronic and optical properties have been studied by varying layer thickness and stacking order. Based on the quantum theory of atoms in molecules, topological analyses on interatomic interactions of layered MX2 and WX2/MoX2, including bond degree (BD), bond length (BL), and bond angle (BA), have been detailed to probe structure-property relationships. Results show that M-X and X-X bonds are strengthened and weakened in layered MX2 compared to the counterparts in bulks. X-X and M-Se/Te are weakened at compressive strain while strengthened at tensile strain and are more responsive to the former than the latter. Discordant BD variation of individual parts of WX2/MoX2 accounts for exclusively distributed electrons and holes, yielding type-II band offsets. X-X BL correlates positively to binding energy (Eb), while X-X BA correlates negatively to lattice mismatch (lm). The resulting interlayer distance limitation evidences constraint-free lattice of vdW structure. Finally, the connection between microscopic interatomic interaction and macroscopic electromagnetic behavior has been quantified firstly by a cubic equation relating to weighted BD summation and static dielectric constant.

scholarly journals Structure-Property Relationships of 2D Ga/In Chalcogenides

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2188
Author(s):  
Pingping Jiang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Density Functional ◽  
Lattice Mismatch ◽  
Decisive Role ◽  
Interatomic Interaction ◽  
Structure Property ◽  
Functional Theory ◽  
Structure Property Relationships ◽  
Structure Property Relationship ◽  
Maximum Conversion Efficiency

Two-dimensional MX (M = Ga, In; X = S, Se, Te) homo- and heterostructures are of interest in electronics and optoelectronics. Structural, electronic and optical properties of bulk and layered MX and GaX/InX heterostructures have been investigated comprehensively using density functional theory (DFT) calculations. Based on the quantum theory of atoms in molecules, topological analyses of bond degree (BD), bond length (BL) and bond angle (BA) have been detailed for interpreting interatomic interactions, hence the structure–property relationship. The X–X BD correlates linearly with the ratio of local potential and kinetic energy, and decreases as X goes from S to Te. For van der Waals (vdW) homo- and heterostructures of GaX and InX, a cubic relationship between microscopic interatomic interaction and macroscopic electromagnetic behavior has been established firstly relating to weighted absolute BD summation and static dielectric constant. A decisive role of vdW interaction in layer-dependent properties has been identified. The GaX/InX heterostructures have bandgaps in the range 0.23–1.49 eV, absorption coefficients over 10−5 cm−1 and maximum conversion efficiency over 27%. Under strain, discordant BD evolutions are responsible for the exclusively distributed electrons and holes in sublayers of GaX/InX. Meanwhile, the interlayer BA adjustment with lattice mismatch explains the constraint-free lattice of the vdW heterostructure.

scholarly journals Optical Properties of Al- and Zr-Doped Rutile Single Crystals Grown by Tilting-Mirror-Type Floating Zone Method and Study of Structure-Property Relationships by First Principle Calculations

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Md. Abdur Razzaque Sarker
Keyword(s):  
Optical Properties ◽  
Single Crystals ◽  
Floating Zone ◽  
Structure Property ◽  
Etch Pits ◽  
Zone Method ◽  
Electronic And Optical Properties ◽  
Optical Micrograph ◽  
Structure Property Relationships ◽  
Effect Of Doping

High quality and transparent single crystals of undoped rutile TiO2, Al-doped rutile (Al : TiO2), and Zr-doped rutile (Zr : TiO2) have been grown successfully by tilting-mirror-type floating zone (TMFZ) using travelling solvent floating (TSFZ) technique. The effect of doping on the electronic and optical properties of rutile has been studied experimentally as well as by simulation calculations. The effect of doping on the quality of crystals was also investigated by observing optical micrograph and measuring etch pits density that reveals the presence of defects. Undoped rutile crystals were dark blue and comprised many low-angle grain boundaries. Al+3 and Zr+4 ions pin down the migration of dislocations during the cooling and create oxygen vacancies. Doping of the impurities would improve the electronic and optical properties of rutile. The elastic properties might be changed for doping of the impurities in the rutile crystals.

scholarly journals Structure–Property Relationships in Transition Metal Dichalcogenide Bilayers under Biaxial Strains

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2639
Author(s):  
Pingping Jiang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Density Functional ◽  
Compressive Strain ◽  
Bond Critical Point ◽  
Transition Metal Dichalcogenide ◽  
Structure Property ◽  
Photovoltaic Properties ◽  
Functional Theory ◽  
Leading Role ◽  
Structure Property Relationships

This paper reports a Density Functional Theory (DFT) investigation of the electron density and optoelectronic properties of two-dimensional (2D) MX2 (M = Mo, W and X = S, Se, Te) subjected to biaxial strains. Upon strains ranging from −4% (compressive strain) to +4% (tensile strain), MX2 bilayers keep the same bandgap type but undergo a non-symmetrical evolution of bandgap energies and corresponding effective masses of charge carriers (m*). Despite a consistency regarding the electronic properties of Mo- and WX2 for a given X, the strain-induced bandgap shrinkage and m* lowering are strong enough to alter the strain-free sequence MTe2, MSe2, MS2, thus tailoring the photovoltaic properties, which are found to be direction dependent. Based on the quantum theory of atoms in molecules, the bond degree (BD) at the bond critical points was determined. Under strain, the X-X BD decreases linearly as X atomic number increases. However, the kinetic energy per electron G/ρ at the bond critical point is independent of strains with the lowest values for X = Te, which can be related to the highest polarizability evidenced from the dielectric properties. A cubic relationship between the absolute BD summation of M-X and X-X bonds and the static relative permittivity was observed. The dominant position of X-X bond participating in this cubic relationship in the absence of strain was substantially reinforced in the presence of strain, yielding the leading role of the X-X bond instead of the M-X one in the photovoltaic response of 2D MX2 material.

Novel Polar Intermetallic π-Systems along the Zintl Border

1998 ◽  
Vol 547 ◽  
Author(s):  
Arnold M. Guloy ◽  
Zhihong Xu
Keyword(s):  
Electronic Materials ◽  
Structure Property ◽  
Zintl Phases ◽  
Group 13 ◽  
Structure Property Relationships ◽  
Inorganic Systems ◽  
Rich Diversity ◽  
Structures And Properties ◽  
Potential Applications

AbstractStudies have shown that complex Zintl phases exhibit a rich diversity of crystal structures. These have also revealed a remarkable success of the Zintl concept in rationalizing stoichiometry, crystal structure and chemical bonding of many main group intermetallics. Still there are unresolved questions about the usefulness of the concept in explaining structure-property relationships in intermetallics near the Zintl border, and as a rational tool in designing new materials. Limitations of the concept are represented by violations often associated with “electron-deficient” phases that contain Group 13 metalloids. Recent investigations on “electron-deficient” Zintl phases containing post transition metals have led to the synthesis of a number of novel inorganic-intermetallic π-systems. Since unique structures and properties are already apparent in normal Zintl phases, it is anticipated that the exploratory synthesis and characterization of conjugated and multiple-bonded inorganic systems will produce not only unusual crystal chemistry but interesting physical properties as well. We report on new complex Zintl phases that include the semiconducting SrCa2In2Ge - which features [In2Ge]6- chains and represents a novel inorganic conjugated π-system analogous to a polyallyl chain with In-In double bonds, and Ca5In9Sn6 - which contains In trimers, [In3]5- analogous and isoelectronic with the aromatic cyclopropenium cation, [C3H3]+. These unusual materials, Zintl π-systems, represent a promising class of electronic materials with a range of potential applications.

An Overview of Conjugated Polymers in their Insulating Forms

1992 ◽  
Vol 247 ◽  
Author(s):  
Daniel J. Sandman
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Conjugated Polymers ◽  
Single Crystals ◽  
Optical Spectroscopy ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Device Applications ◽  
Linear Optical Properties ◽  
Linear Optical

ABSTRACTA brief overview is presented of the electrical and linear optical properties of conjugated polymers in their electrically insulating forms. Topics discussed include electronic structure and optical spectroscopy, thermochromism, and device applications, particularly electroluminescence. Structure-property relationships are stressed. Particular emphasis is placed on the properties of polydiacetylenes as they are available as macroscopic single crystals and, hence, are the best defined class of conjugated polymers.

An overview of phosphorescent metallomesogens based on platinum and iridium

2018 ◽  
Vol 6 (37) ◽  
pp. 9848-9860 ◽  
Author(s):  
Xiugang Wu ◽  
Mengbing Zhu ◽  
Duncan W. Bruce ◽  
Weiguo Zhu ◽  
Yafei Wang
Keyword(s):  
Optical Properties ◽  
Liquid Crystals ◽  
Quantum Efficiency ◽  
Molecular Design ◽  
Internal Quantum Efficiency ◽  
Structure Property ◽  
Metal Centers ◽  
Structure Property Relationships

Metallomesogens – liquid crystals containing metal centers – have attracted much interest owing to their interesting magnetic and electro-optical properties. Due to the theoretical 100% internal quantum efficiency, here, a brief overview of recent research on platinum/iridium-based metallomesogens including their molecular design and structure-property relationships is reported.

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