Inverted all-polymer solar cells based on a quinoxaline-thiophene/naphthalene-diimide polymer blend improved by annealing
Journal article, 2016

We have investigated the effect of thermal annealing on the photovoltaic parameters of all-polymer solar cells based on a quinoxaline-thiophene donor polymer (TQ1) and a naphthalene diimide acceptor polymer (N2200). The annealed devices show a doubled power conversion efficiency compared to nonannealed devices, due to the higher short-circuit current (J(sc)) and fill factor (FF), but with a lower open circuit voltage (V-oc). On the basis of the morphology-mobility examination by several scanning force microscopy techniques, and by grazing-incidence wide-angle X-ray scattering, we conclude that better charge transport is achieved by higher order and better interconnected networks of the bulk heterojunction in the annealed active layers. The annealing improves charge transport and extends the conjugation length of the polymers, which do help in charge generation and meanwhile reduce recombination. Photoluminescence, electroluminescence, and light intensity dependence measurements reveal how this morphological change affects charge generation and recombination. As a result, the J(sc) and FF are significantly improved. However, the smaller band gap and the higher HOMO level of TQ1 upon annealing causes a lower V-oc. The blend of an amorphous polymer TQ1, and a semi-crystalline polymer N2200, can thus be modified by thermal annealing to double the power conversion efficiency.

acceptor

performance

crystallinity

open-circuit voltage

high-mobility

photovoltaics

efficiency

aggregation

morphology

conjugated polymers

Author

Y. X. Xia

Linköping University

Jinan University

C. Musumeci

Linköping University

J. Bergqvist

Linköping University

W. Ma

Xi'an Jiaotong University

F. Gao

Linköping University

Z. Tang

Linköping University

S. Bai

Linköping University

Y. Z. Jin

Zhejiang University

C. H. Zhu

Lawrence Berkeley National Laboratory

Renee Kroon

University of South Australia

C. F. Wang

Lawrence Berkeley National Laboratory

Mats Andersson

University of South Australia

Lintao Hou

Jinan University

Olle Inganäs

Linköping University

Ergang Wang

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

Journal of Materials Chemistry A

20507488 (ISSN) 20507496 (eISSN)

Vol. 4 10 3835-3843

Subject Categories

Environmental Engineering

Polymer Technologies

DOI

10.1039/c6ta00531d

More information

Latest update

5/23/2018