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Title: Design principles for the energy level tuning in donor/acceptor conjugated polymers

Abstract

To identify reliable molecular design principles for energy level tuning in donor/acceptor conjugated polymers (CPs), we studied the governing factors by means of ab initio calculations based on density-functional theory (DFT). We investigated a series of CPs in which we independently and systematically varied the electron withdrawing power of the acceptor unit and the electron donating power of the donor unit, while maintaining the same conjugated chain conformation. We observed that the introduction of a stronger acceptor unit, while keeping the same donor unit in the CP, lowers the LUMO level, but leaves the HOMO level almost unchanged. Conversely, enhancing the strength of the donor unit for the same acceptor unit raises the HOMO level, while maintaining the LUMO level. We identified strong correlations between the frontier orbital energy levels and the degree of orbital localization, which depends on the electron donating or withdrawing power of the molecular groups carrying the orbitals. Moreover, the HOMO/LUMO gap of the CP is directly proportional to the charge transfer between donating and accepting units, which provides a robust design criterion for CPs.

Authors:
ORCiD logo [1];  [1];  [1];  [1]; ORCiD logo [1]
  1. Department of Materials Science and Engineering, University of Michigan; Ann Arbor; USA
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Solar and Thermal Energy Conversion (CSTEC); Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1566632
DOE Contract Number:  
SC0000957
Resource Type:
Journal Article
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Volume: 21; Journal Issue: 2; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
solar (photovoltaic), solar (thermal), phonons, thermal conductivity, thermoelectric, electrodes - solar, defects, charge transport, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Hashemi, Daniel, Ma, Xiao, Ansari, Ramin, Kim, Jinsang, and Kieffer, John. Design principles for the energy level tuning in donor/acceptor conjugated polymers. United States: N. p., 2019. Web. doi:10.1039/c8cp03341b.
Hashemi, Daniel, Ma, Xiao, Ansari, Ramin, Kim, Jinsang, & Kieffer, John. Design principles for the energy level tuning in donor/acceptor conjugated polymers. United States. doi:10.1039/c8cp03341b.
Hashemi, Daniel, Ma, Xiao, Ansari, Ramin, Kim, Jinsang, and Kieffer, John. Tue . "Design principles for the energy level tuning in donor/acceptor conjugated polymers". United States. doi:10.1039/c8cp03341b.
@article{osti_1566632,
title = {Design principles for the energy level tuning in donor/acceptor conjugated polymers},
author = {Hashemi, Daniel and Ma, Xiao and Ansari, Ramin and Kim, Jinsang and Kieffer, John},
abstractNote = {To identify reliable molecular design principles for energy level tuning in donor/acceptor conjugated polymers (CPs), we studied the governing factors by means of ab initio calculations based on density-functional theory (DFT). We investigated a series of CPs in which we independently and systematically varied the electron withdrawing power of the acceptor unit and the electron donating power of the donor unit, while maintaining the same conjugated chain conformation. We observed that the introduction of a stronger acceptor unit, while keeping the same donor unit in the CP, lowers the LUMO level, but leaves the HOMO level almost unchanged. Conversely, enhancing the strength of the donor unit for the same acceptor unit raises the HOMO level, while maintaining the LUMO level. We identified strong correlations between the frontier orbital energy levels and the degree of orbital localization, which depends on the electron donating or withdrawing power of the molecular groups carrying the orbitals. Moreover, the HOMO/LUMO gap of the CP is directly proportional to the charge transfer between donating and accepting units, which provides a robust design criterion for CPs.},
doi = {10.1039/c8cp03341b},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
issn = {1463-9076},
number = 2,
volume = 21,
place = {United States},
year = {2019},
month = {1}
}

Works referenced in this record:

Conjugated Polymer-Based Organic Solar Cells
journal, April 2007

  • Günes, Serap; Neugebauer, Helmut; Sariciftci, Niyazi Serdar
  • Chemical Reviews, Vol. 107, Issue 4, p. 1324-1338
  • DOI: 10.1021/cr050149z