Possible Routes for Efficient Thermo‐Electric Energy Conversion in a Molecular Junction

Abstract

In the context of designing an efficient thermoelectric energy‐conversion device at nanoscale level, we suggest several important tuning parameters to enhance the performance of thermoelectric converters. We consider a simple molecular junction, which is always helpful to understand the basic mechanisms in a deeper way, where a benzene molecule is coupled to two external baths having unequal temperatures. The key component responsible for achieving better performance is associated with the asymmetric nature of transmission function, and in the present work, we show that it can be implemented in different ways by regulating the physical parameters involving the system. Employing a tight‐binding framework we calculate electrical and thermal conductances, thermopower, and figure of merit (FOM) by using Landauer integrals, and thoroughly examine the critical roles played by molecule‐to‐lead (ML) interface geometry, magnetic field, chemical substituent group, ML coupling, and the direct coupling between the two leads. Our results show that a reasonably large FOM (≫1) can be obtained and lead to a possibility of regulating the efficiency by selectively tuning the physical parameters. We believe that the present analysis will enhance the understanding of designing efficient thermoelectric devices, and can be verified in a laboratory.

Thermal Properties of Ordered and Disordered DNA Chains: Efficient Energy Conversion

“…Now, whenever we talk about the thermoelectric energy conversion, we need to focus on the conversion efficiency which is measured by the quantity figure of merit , usually referred as ZT . To make the device competitive with present thermoelectric devices, ZT should be at least comparable to unity, and, higher value of ZT ( ) is thus always favorable.…”

Thermoelectric Effect in a Fibonacci Chain with AAH Modulation: A Theoretical Study

“…we compute S , G , and K el following the Landauer integrals. [ 42–44 ] These are given by $$\begin{equation} S=-\frac{ L_1}{e T L_0} \end{equation}$$ $$\begin{equation} G=2 e^2 L_0 \end{equation}$$ $$\begin{equation} K_{\text{el}}=\frac{2}{T}{\left(L_2-\frac{L_{1}^2}{L_0}\right)} \end{equation}$$The different quantities L n ( n = 0, 1, 2), used in above equations, are determined from the expression $$\begin{equation} L_{n}=-\frac{1}{h} \int \limits _{-\infty }^{\infty }\tau (E){\left(\frac{\partial f}{\partial T}\right)} (E-E_\text{f})^{n} {\text{d}}E \end{equation}$$where f ( E ) is the Fermi–Dirac distribution function and E f is the equilibrium Fermi energy.…”

Thermoelectricity in a Quasiperiodic Lattice Beyond Nearest‐Neighbor Electron Hopping

“…The quantities G, S and k el are computed from the Landauer integrals through the relations [18,19,38,39] G = 2e 2 L 0 (8)…”

“…The fundamental mechanism of getting a favorable response relies on how much the transmission function is asymmetric across the energy around which the response is being determined. [18,19] More asymmetricity yields a more favorable response. Compared to different propositions available in the literature, in the present manuscript, we provide a new prescription that is quite interesting and important as well.…”

“…The nature of energy eigenstates is characterized by calculating inverse participation ratios, [ 28,37 ] through which the distribution of particles at different lattice sites can directly be estimated—a simple way of predicting whether a state is conducting or not. The thermoelectric quantities, which include electrical conductance ( G ), Seebeck coefficient ( S ) and thermal conductance due to electrons ($$k_{el}$$), are obtained from the Landauer integrals, [ 18,19,38,39 ] and the two‐terminal electron transmission probability, involved in these quantities, is determined via the standard Green's function formalism. [ 40–45 ] For the calculation of phonon thermal conductance ($$k_{ph}$$) and phonon transmission probability we also follow the Green's function technique, which is elaborately discussed in refs.…”