Substituent Control of σ-interference Effects in the Transmission of Saturated Molecules

The single-molecule conductance of saturated molecules can potentially be fully suppressed by destructive quantum interference in their σ-system. However, only few molecules with σ-interference have been identified and the structure-property relationship remains to be elucidated. Here, we explore the role of substituents in modulating the electronic transmission of saturated molecules. In functionalized bicyclo[2.2.2]octanes, the transmission is suppressed by σ- interference when fluorine substituents are applied. For bicyclo[2.2.2]octasilane and - octagermanes the transmission is suppressed when carbon-based substituents are used, and such molecules are likely to be highly insulating. For the carbon-based substituents we find a strong correlation between the appropriate Hammett constants and the transmission. The substituent effect enables systematic optimization of the insulating properties of saturated molecular cores.

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The role of Nb2O5 polymorphs on processing–structure–property relationship in lead-based perovskite 0.5Pb(Yb1/2Nb1/2)O3-0.5PbTiO3 piezoceramics

Materialia ◽

10.1016/j.mtla.2021.101255 ◽

2021 ◽

pp. 101255

Author(s):

Erdem Akça ◽

Begüm Ünveroğlu ◽

İstek Tatar ◽

Cihangir Duran

Keyword(s):

Structure Property ◽

Property Relationship ◽

Structure Property Relationship

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Structure-Property Relationships of 2D Ga/In Chalcogenides

Nanomaterials ◽

10.3390/nano10112188 ◽

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.

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