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Title: Molecular Optoelectronics

Abstract

The project developed theoretical tools for analysis of nanodevices subjected to external optical and bias driving. Traditional theoretical techniques for open nonequilibrium systems are based on either quasiparticle description (e.g., standard nonequilibrium Green's functions) or utilizer kinetic schemes (e.g., Lindblad/Redfield quantum master equations. The former approach becomes inconvenient when applied to single molecule junctions, where electronic structure of the system (molecule) is sensitive to charging and excitation processes (as a result, one has to deal with such artificial concepts as "renormalization of molecular orbitals"). The latter technique fails to describe hybridization between molecular and contacts states and thus in principle cannot model response of such devices (e.g., conductance and optical spectra). Moreover, utilization of kinetic schemes in open interacting systems may lead to qualitative failures in prediction of their responses to external perturbations. We developed a new technique - the Hubbard nonequilibrium Green's functions approach - which allows to avoid shortcomings of standard theoretical approaches. The Hubbard NEGF was applied to analysis of experimental measurements of photoinduced current and bias-induced electroluminescence in STM molecular junctions. In particular, it allows to account for intra-molecular Coulomb interaction in an easy, exact, and efficient way. The latter is is crucial for reproducing experimentalmore » result on electroluminescence for a single phthalocyanine molecule: it naturally explains observed pronounced difference between transport and optical gaps by transitions between different pairs of molecular many-body states (electronic transitions contributing to transport gap are transitions between states with different number of electrons on the molecule, optical transition contributing to measured spectrum are transition between many-body molecular states with the same number of electrons). Similarly, ability of the Hubbard NEGF to formulate junction responses in the basis of many-body molecular states is useful in analyses of photo-induced currents and selective triplet formation in STM molecular junctions. We also demonstrated practical usefulness of the Hubbard NEGF within newly proposed general theory (any intra-molecular interactions, arbitrary electron-nuclei coupling, beyond strictly adiabatic description) of current induced forces for nonadiabatic molecular dynamics. Finally, following latest trends in laser techniques we studied local responses (local fluxes and local noise spectroscopy) of biased junctions as a source of information not accessible by total responses (total fluxes and noises) of the system.« less

Authors:
ORCiD logo
Publication Date:
Research Org.:
The Regents of the University of California. University of California, San Diego
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1728708
Report Number(s):
DOE-UCSD-18201
DOE Contract Number:  
SC0018201
Resource Type:
Technical Report
Resource Relation:
Related Information: Publications which resulted from the Award are referenced below
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 97 MATHEMATICS AND COMPUTING; 30 DIRECT ENERGY CONVERSION; molecular optoelectronics, STM, photocurrent, electroluminescence, electronic friction, local fluxes, kinetic schemes, Hubbard NEGF

Citation Formats

Galperin, Michael. Molecular Optoelectronics. United States: N. p., 2020. Web. doi:10.2172/1728708.
Galperin, Michael. Molecular Optoelectronics. United States. https://doi.org/10.2172/1728708
Galperin, Michael. 2020. "Molecular Optoelectronics". United States. https://doi.org/10.2172/1728708. https://www.osti.gov/servlets/purl/1728708.
@article{osti_1728708,
title = {Molecular Optoelectronics},
author = {Galperin, Michael},
abstractNote = {The project developed theoretical tools for analysis of nanodevices subjected to external optical and bias driving. Traditional theoretical techniques for open nonequilibrium systems are based on either quasiparticle description (e.g., standard nonequilibrium Green's functions) or utilizer kinetic schemes (e.g., Lindblad/Redfield quantum master equations. The former approach becomes inconvenient when applied to single molecule junctions, where electronic structure of the system (molecule) is sensitive to charging and excitation processes (as a result, one has to deal with such artificial concepts as "renormalization of molecular orbitals"). The latter technique fails to describe hybridization between molecular and contacts states and thus in principle cannot model response of such devices (e.g., conductance and optical spectra). Moreover, utilization of kinetic schemes in open interacting systems may lead to qualitative failures in prediction of their responses to external perturbations. We developed a new technique - the Hubbard nonequilibrium Green's functions approach - which allows to avoid shortcomings of standard theoretical approaches. The Hubbard NEGF was applied to analysis of experimental measurements of photoinduced current and bias-induced electroluminescence in STM molecular junctions. In particular, it allows to account for intra-molecular Coulomb interaction in an easy, exact, and efficient way. The latter is is crucial for reproducing experimental result on electroluminescence for a single phthalocyanine molecule: it naturally explains observed pronounced difference between transport and optical gaps by transitions between different pairs of molecular many-body states (electronic transitions contributing to transport gap are transitions between states with different number of electrons on the molecule, optical transition contributing to measured spectrum are transition between many-body molecular states with the same number of electrons). Similarly, ability of the Hubbard NEGF to formulate junction responses in the basis of many-body molecular states is useful in analyses of photo-induced currents and selective triplet formation in STM molecular junctions. We also demonstrated practical usefulness of the Hubbard NEGF within newly proposed general theory (any intra-molecular interactions, arbitrary electron-nuclei coupling, beyond strictly adiabatic description) of current induced forces for nonadiabatic molecular dynamics. Finally, following latest trends in laser techniques we studied local responses (local fluxes and local noise spectroscopy) of biased junctions as a source of information not accessible by total responses (total fluxes and noises) of the system.},
doi = {10.2172/1728708},
url = {https://www.osti.gov/biblio/1728708}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2020},
month = {12}
}