36 research outputs found
First-principles quantum transport modeling of thermoelectricity in single-molecule nanojunctions with graphene nanoribbon electrodes
We overview nonequilibrium Green function combined with density functional
theory (NEGF-DFT) modeling of independent electron and phonon transport in
nanojunctions with applications focused on a new class of thermoelectric
devices where a single molecule is attached to two metallic zigzag graphene
nanoribbons (ZGNRs) via highly transparent contacts. Such contacts make
possible injection of evanescent wavefunctions from ZGNRs, so that their
overlap within the molecular region generates a peak in the electronic
transmission. Additionally, the spatial symmetry properties of the transverse
propagating states in the ZGNR electrodes suppress hole-like contributions to
the thermopower. Thus optimized thermopower, together with diminished phonon
conductance through a ZGNR/molecule/ZGNR inhomogeneous structure, yields the
thermoelectric figure of merit ZT~0.5 at room temperature and 0.5<ZT<2.5 below
liquid nitrogen temperature. The reliance on evanescent mode transport and
symmetry of propagating states in the electrodes makes the
electronic-transport-determined power factor in this class of devices largely
insensitive to the type of sufficiently short conjugated organic molecule,
which we demonstrate by showing that both 18-annulene and C10 molecule
sandwiched by the two ZGNR electrodes yield similar thermopower. Thus, one can
search for molecules that will further reduce the phonon thermal conductance
(in the denominator of ZT) while keeping the electronic power factor (in the
nominator of ZT) optimized. We also show how often employed Brenner empirical
interatomic potential for hydrocarbon systems fails to describe phonon
transport in our single-molecule nanojunctions when contrasted with
first-principles results obtained via NEGF-DFT methodology.Comment: 20 pages, 6 figures; mini-review article prepared for the special
issue of the Journal of Computational Electronics on "Simulation of Thermal,
Thermoelectric, and Electrothermal Phenomena in Nanostructures", edited by I.
Knezevic and Z. Aksamij
Vibration control of composite plates via optimal placement of piezoelectric patches
Journal of Intelligent Material Systems and Structures144-5229-245JMSS
Topology optimization of piezoelectric sensors/actuators for torsional vibration control of composite plates
10.1088/0964-1726/15/2/004Smart Materials and Structures152253-269SMST
Weighted energy linear quadratic regulator vibration control of piezoelectric composite plates
10.1088/0964-1726/11/1/311Smart Materials and Structures11198-106SMST
LQR vibration control of piezoelectric composite plates
10.1117/12.420879Proceedings of SPIE - The International Society for Optical Engineering4235375-386PSIS
Dynamic stability analysis of finite element modeling of piezoelectric composite plates
10.1016/j.ijsolstr.2003.09.041International Journal of Solids and Structures413-4745-76
Optimal placement of piezoelectric sensor/actuator pairs for vibration control of composite plates
10.1117/12.475258Proceedings of SPIE - The International Society for Optical Engineering4693461-471PSIS
Vibration control of smart piezoelectric composite plates
10.1088/0964-1726/10/4/306Smart Materials and Structures104637-644SMST