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Design, Synthesis and Computational Study of Fluorinated Quinoxaline-Oligothiophene-based Conjugated Polymers with Broad Spectral Coverage

Gedefaw, Desta; Hedström, Svante LU ; Xia, Yuxin; Persson, Petter LU and Andersson, Mats R. (2018) In ChemPhysChem 19(24). p.3393-3400
Abstract

Donor-acceptor (D-A) copolymers typically show two absorption peaks in the visible region, flanking a valley region of limited absorptivity. One strategy for more panchromatic light harvesting is to incorporate side-groups orthogonal to the polymer backbone, which enable 2D π conjugation and can give rise to additional absorption peaks. Here we design and synthesize two D-A polymers which both carry a fluorinated quinoxaline acceptor unit, but while P1 includes a benzodithiophene donor moiety with thiophene side-groups (2D-BDT), the P2 polymer lacks 2D conjugation in its simpler pentathiophene donor segment. The P1 polymer consequently shows an atypical absorption profile with more panchromatic absorption with no apparent valley in the... (More)

Donor-acceptor (D-A) copolymers typically show two absorption peaks in the visible region, flanking a valley region of limited absorptivity. One strategy for more panchromatic light harvesting is to incorporate side-groups orthogonal to the polymer backbone, which enable 2D π conjugation and can give rise to additional absorption peaks. Here we design and synthesize two D-A polymers which both carry a fluorinated quinoxaline acceptor unit, but while P1 includes a benzodithiophene donor moiety with thiophene side-groups (2D-BDT), the P2 polymer lacks 2D conjugation in its simpler pentathiophene donor segment. The P1 polymer consequently shows an atypical absorption profile with more panchromatic absorption with no apparent valley in the spectrum. In order to understand the structure-electronic relations, the optical and electrochemical properties were predicted using a previously developed computational approach. The predicted optical properties show very good agreement with the experimental results. Solar cells made from P1 show a short-circuit current more than twice as large as P2, attributed to its enhanced spectral coverage. However, poor fill factors limit the preliminary power conversion efficiencies to 3.3 % for P1 and 1.0 % for P2 as blended with PCBM[70] in a 1 : 1.5 (w/w) ratio.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
computational chemistry, cross-coupling, semiconductors, structure-activity relationships, UV/Vis spectroscopy
in
ChemPhysChem
volume
19
issue
24
pages
3393 - 3400
publisher
John Wiley & Sons
external identifiers
  • scopus:85057558479
ISSN
1439-4235
DOI
10.1002/cphc.201800814
language
English
LU publication?
yes
id
5d22d0e8-fe6b-40db-8706-261a866a55a7
date added to LUP
2018-12-21 09:11:06
date last changed
2019-02-20 11:40:36
@article{5d22d0e8-fe6b-40db-8706-261a866a55a7,
  abstract     = {<p>Donor-acceptor (D-A) copolymers typically show two absorption peaks in the visible region, flanking a valley region of limited absorptivity. One strategy for more panchromatic light harvesting is to incorporate side-groups orthogonal to the polymer backbone, which enable 2D π conjugation and can give rise to additional absorption peaks. Here we design and synthesize two D-A polymers which both carry a fluorinated quinoxaline acceptor unit, but while P1 includes a benzodithiophene donor moiety with thiophene side-groups (2D-BDT), the P2 polymer lacks 2D conjugation in its simpler pentathiophene donor segment. The P1 polymer consequently shows an atypical absorption profile with more panchromatic absorption with no apparent valley in the spectrum. In order to understand the structure-electronic relations, the optical and electrochemical properties were predicted using a previously developed computational approach. The predicted optical properties show very good agreement with the experimental results. Solar cells made from P1 show a short-circuit current more than twice as large as P2, attributed to its enhanced spectral coverage. However, poor fill factors limit the preliminary power conversion efficiencies to 3.3 % for P1 and 1.0 % for P2 as blended with PCBM[70] in a 1 : 1.5 (w/w) ratio.</p>},
  author       = {Gedefaw, Desta and Hedström, Svante and Xia, Yuxin and Persson, Petter and Andersson, Mats R.},
  issn         = {1439-4235},
  keyword      = {computational chemistry,cross-coupling,semiconductors,structure-activity relationships,UV/Vis spectroscopy},
  language     = {eng},
  month        = {12},
  number       = {24},
  pages        = {3393--3400},
  publisher    = {John Wiley & Sons},
  series       = {ChemPhysChem},
  title        = {Design, Synthesis and Computational Study of Fluorinated Quinoxaline-Oligothiophene-based Conjugated Polymers with Broad Spectral Coverage},
  url          = {http://dx.doi.org/10.1002/cphc.201800814},
  volume       = {19},
  year         = {2018},
}