Thermo-Electrical Conduction of the 2,7-Di([1,1’-Biphenyl]-4-yl)-9H-Fluorene Molecular System: Coupling between Benzene Rings and Stereoelectronic Effects

• Main Authors: Judith Helena Ojeda Silva, Juan Sebastián Paez Barbosa, Carlos Alberto Duque Echeverri
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Molecules
• Subjects: green’s functions; decimation process; thermal and electric properties; stereoelectronic effect
• Online Access: https://www.mdpi.com/1420-3049/25/14/3215

Theoretical and analytical thermal and electrical properties are studied through the 2,7-Di([1,1’-biphenyl]-4-yl)-9H-fluorene aromatic system as a prototype of a molecular switch. Variations of the dihedral angles between the two Benzene rings at each end of the molecule have been considered, thus determining the dependence on the structural variation of the molecule when the aromatic system is connected between metal contacts. The molecule is modeled through a Tight-Binding Hamiltonian where—from the analytical process of decimation and using Green’s functions—the probability of transmission (<i>T</i>) is calculated by using the Fisher–Lee relationship. Consequently, the thermal and electrical transport properties such as <inline-formula> <math display="inline"> <semantics> <mrow> <mi>I</mi> <mo>−</mo> <mi>V</mi> </mrow> </semantics> </math> </inline-formula> curves, quantum noise (<i>S</i>), Fano factor (<i>F</i>), electrical conductance (<i>G</i>), thermal conductance (<inline-formula> <math display="inline"> <semantics> <mi>κ</mi> </semantics> </math> </inline-formula>), Seebeck coefficient (<i>Q</i>), and merit number (<inline-formula> <math display="inline"> <semantics> <mrow> <mi>Z</mi> <mi>T</mi> </mrow> </semantics> </math> </inline-formula>) are calculated. The available results offer the possibility of designing molecular devices, where the change in conductance or current induced by a stereoelectronic effect on the molecular junctions (within the aromatic system) can produce changes on the insulating–conductive states.