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Title: Variation of the Side Chain Branch Position Leads to Vastly Improved Molecular Weight and OPV Performance in 4,8-dialkoxybenzo[1,2-b:4,5-b′]dithiophene/2,1,3-benzothiadiazole Copolymers

Abstract

Through manipulation of the solubilizing side chains, we were able to dramatically improve the molecular weight ( M w ) of 4,8-dialkoxybenzo[1,2- b :4,5- b ]dithiophene (BDT)/2,1,3-benzothiadiazole (BT) copolymers. When dodecyl side chains ( P1 ) are employed at the 4- and 8-positions of the BDT unit, we obtain a chloroform-soluble copolymer fraction with M w of 6.3 kg/mol. Surprisingly, by moving to the commonly employed 2-ethylhexyl branch ( P2 ), M w decreases to 3.4 kg/mol. This is despite numerous reports that this side chain increases solubility and M w . By moving the ethyl branch in one position relative to the polymer backbone (1-ethylhexyl, P3 ), M w is dramatically increased to 68.8 kg/mol. As a result of this M w increase, the shape of the absorption profile is dramatically altered, with λ max = 637 nm compared with 598 nm for P1 and 579 nm for P2 . The hole mobility as determined by thin film transistor (TFT) measurements is improved from ~ 1 × 10 6  cm 2 /Vs for P1 and P2 to 7 × 10 4  cm 2 /Vs for P3 , while solar cell power conversion efficiency in increased to 2.91 % for P3 relative to 0.31 % and 0.19 % for P1 and P2 , respectively.

Authors:
 [1];  [2];  [1];  [1];  [1];  [1];  [1];  [2];  [1];  [1]
  1. The Department of Physics and the Center for Nanotechnology and Molecular Materials, Wake Forest University, Winston-Salem, NC 27109, USA
  2. The Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1197856
Grant/Contract Number:  
FG02-07ER46428
Resource Type:
Published Article
Journal Name:
Journal of Nanotechnology
Additional Journal Information:
Journal Name: Journal of Nanotechnology Journal Volume: 2011; Journal ID: ISSN 1687-9503
Publisher:
Hindawi Publishing Corporation
Country of Publication:
Country unknown/Code not available
Language:
English

Citation Formats

Coffin, Robert C., MacNeill, Christopher M., Peterson, Eric D., Ward, Jeremy W., Owen, Jack W., McLellan, Claire A., Smith, Gregory M., Noftle, Ronald E., Jurchescu, Oana D., and Carroll, David L. Variation of the Side Chain Branch Position Leads to Vastly Improved Molecular Weight and OPV Performance in 4,8-dialkoxybenzo[1,2-b:4,5-b′]dithiophene/2,1,3-benzothiadiazole Copolymers. Country unknown/Code not available: N. p., 2011. Web. doi:10.1155/2011/572329.
Coffin, Robert C., MacNeill, Christopher M., Peterson, Eric D., Ward, Jeremy W., Owen, Jack W., McLellan, Claire A., Smith, Gregory M., Noftle, Ronald E., Jurchescu, Oana D., & Carroll, David L. Variation of the Side Chain Branch Position Leads to Vastly Improved Molecular Weight and OPV Performance in 4,8-dialkoxybenzo[1,2-b:4,5-b′]dithiophene/2,1,3-benzothiadiazole Copolymers. Country unknown/Code not available. doi:10.1155/2011/572329.
Coffin, Robert C., MacNeill, Christopher M., Peterson, Eric D., Ward, Jeremy W., Owen, Jack W., McLellan, Claire A., Smith, Gregory M., Noftle, Ronald E., Jurchescu, Oana D., and Carroll, David L. Sat . "Variation of the Side Chain Branch Position Leads to Vastly Improved Molecular Weight and OPV Performance in 4,8-dialkoxybenzo[1,2-b:4,5-b′]dithiophene/2,1,3-benzothiadiazole Copolymers". Country unknown/Code not available. doi:10.1155/2011/572329.
@article{osti_1197856,
title = {Variation of the Side Chain Branch Position Leads to Vastly Improved Molecular Weight and OPV Performance in 4,8-dialkoxybenzo[1,2-b:4,5-b′]dithiophene/2,1,3-benzothiadiazole Copolymers},
author = {Coffin, Robert C. and MacNeill, Christopher M. and Peterson, Eric D. and Ward, Jeremy W. and Owen, Jack W. and McLellan, Claire A. and Smith, Gregory M. and Noftle, Ronald E. and Jurchescu, Oana D. and Carroll, David L.},
abstractNote = {Through manipulation of the solubilizing side chains, we were able to dramatically improve the molecular weight ( M w ) of 4,8-dialkoxybenzo[1,2- b :4,5- b ′ ]dithiophene (BDT)/2,1,3-benzothiadiazole (BT) copolymers. When dodecyl side chains ( P1 ) are employed at the 4- and 8-positions of the BDT unit, we obtain a chloroform-soluble copolymer fraction with M w of 6.3 kg/mol. Surprisingly, by moving to the commonly employed 2-ethylhexyl branch ( P2 ), M w decreases to 3.4 kg/mol. This is despite numerous reports that this side chain increases solubility and M w . By moving the ethyl branch in one position relative to the polymer backbone (1-ethylhexyl, P3 ), M w is dramatically increased to 68.8 kg/mol. As a result of this M w increase, the shape of the absorption profile is dramatically altered, with λ max = 637 nm compared with 598 nm for P1 and 579 nm for P2 . The hole mobility as determined by thin film transistor (TFT) measurements is improved from ~ 1 × 10 − 6  cm 2 /Vs for P1 and P2 to 7 × 10 − 4  cm 2 /Vs for P3 , while solar cell power conversion efficiency in increased to 2.91 % for P3 relative to 0.31 % and 0.19 % for P1 and P2 , respectively.},
doi = {10.1155/2011/572329},
journal = {Journal of Nanotechnology},
number = ,
volume = 2011,
place = {Country unknown/Code not available},
year = {2011},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1155/2011/572329

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