D-A(1)-D-A(2) Copolymers with Extended Donor Segments for Efficient Polymer Solar Cells
Journal article, 2015

Typically a donor-acceptor (D-A) design strategy is used for engineering the bandgap of polymers for solar cells. However, in this work, a series of alternating D-A(1-)D-A(2) copolymers PnTQTI(F) were synthesized and characterized with oligothiophenes (nT, n = 1, 2, 3) as the donor and two electron-deficient moieties, quinoxaline and isoindigo, as the acceptors in the repeating unit. We have studied the influence of the donor segments with different numbers of thiophene units and the effect of the addition of fluorine to the quinoxaline unit of the D-A(1)-D-A(2) polymers. The photophysical, electrochemical, and photovoltaic properties of the polymers were examined via a range of techniques and related to theoretical simulations. On increasing the length of the donor thiophene units, broader absorption spectra were observed in addition to a sequential increase in HOMO levels, while the LUMO levels displayed very small variations. The addition of fluorine to the quinoxaline unit not only decreased the HOMO levels of the resulting polymers but also enhanced the absorption coefficients. A superior photovoltaic performance was observed for the P3TQTI-F-based device with a power conversion efficiency (PCE) of 7.0%, which is the highest efficiency for alternating D-A(1)-D-A(2) polymers reported to date. The structureproperty correlations of the PnTQTI(F) polymers demonstrate that varying of the length of the donor segments is a valuable method for designing high-performance D-A(1)-D-A(2) copolymers and highlight the promising nature of D-A(1)-D-A(2) copolymers for efficient bulk-heterojunction solar cells.

Author

Qiang Tao

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Y. X. Xia

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Xiaofeng Xu

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Svante Hedström

Lund University

Olof Bäcke

Chalmers, Applied Physics, Eva Olsson Group

David James

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

P. Persson

Lund University

Eva Olsson

Chalmers, Applied Physics, Eva Olsson Group

Olle Inganäs

Linköping University

Lintao Hou

Jinan University

W. G. Zhu

XiangTan University

Ergang Wang

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Macromolecules

00249297 (ISSN) 15205835 (eISSN)

Vol. 48 4 1009-1016

SUstainable Novel FLexible Organic Watts Efficiently Reliable (SUNFLOWER)

European Commission (FP7), 2011-10-01 -- 2016-03-31.

Subject Categories

Polymer Technologies

Energy Systems

DOI

10.1021/ma502186g

More information

Latest update

11/23/2018