Marked Consequences of Systematic Oligothiophene Catenation in Thieno[3,4-c]pyrrole-4,6-dione and Bithiopheneimide Photovoltaic Copolymers.
As effective building blocks for high-mobility transistor polymers, oligothiophenes are receiving attention for polymer solar cells (PSCs) because the resulting polymers can effectively suppress charge recombination. Here we investigate two series of in-chain donor-acceptor copolymers, PTPDnT and PBTInT, based on thieno[3,4-c]pyrrole-4,6-dione (TPD) or bithiopheneimide (BTI) as electron acceptor units, respectively, and oligothiophenes (nTs) as donor counits, for high-performance PSCs. Intramolecular S···O interaction leads to more planar TPD polymer backbones, however backbone torsion yields greater open-circuit voltages for BTI polymers. Thiophene addition progressively raises polymer HOMOs but marginally affects their band gaps. FT-Raman spectra indicate that PTPDnT and PBTInT conjugation lengths scale with nT catenation up to n = 3 and then saturate for longer oligomer. Furthermore, the effects of oligothiophene alkylation position are explored, revealing that the alkylation pattern greatly affects film morphology and PSC performance. The 3T with "outward" alkylation in PTPD3T and PBTI3T affords optimal π-conjugation, close stacking, long-range order, and high hole mobilities (0.1 cm(2)/(V s)). These characteristics contribute to the exceptional ∼80% fill factors for PTPD3T-based PSCs with PCE = 7.7%. The results demonstrate that 3T is the optimal donor unit among nTs (n = 1-4) for photovoltaic polymers. Grazing incidence wide-angle X-ray scattering, transmission electron microscopy, and time-resolved microwave conductivity measurements reveal that the terthiophene-based PTPD3T blend maintains high crystallinity with appreciable local mobility and long charge carrier lifetime. These results provide fundamental materials structure-device performance correlations and suggest guidelines for designing oligothiophene-based polymers with optimal thiophene catenation and appropriate alkylation pattern to maximize PSC performance.
Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Nanjia
N
Zhou
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Department of Materials Science and Engineering, South University of Science and Technology of China , No. 1088, Xueyuan Boulevard, Shenzhen, Guangdong 518055, China.
Xugang
X
Guo
Department of Physical Chemistry, University of Málaga , Campus de Teatinos s/n, Málaga 29071, Spain.
Rocio
R
Ponce Ortiz
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Tobias
T
Harschneck
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Chemical Sciences and Engineering Division, Argonne National Laboratory , 9700 South Cass Avenue, Lemont, Illinois 60439, United States.
Eric F
EF
Manley
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Sylvia J
SJ
Lou
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Patrick E
PE
Hartnett
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Xinge
X
Yu
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Noah E
NE
Horwitz
Department of Physical Chemistry, University of Málaga , Campus de Teatinos s/n, Málaga 29071, Spain.
Paula
P
Mayorga Burrezo
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Thomas J
TJ
Aldrich
Department of Physical Chemistry, University of Málaga , Campus de Teatinos s/n, Málaga 29071, Spain.
Juan T
JT
López Navarrete
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Michael R
MR
Wasielewski
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Chemical Sciences and Engineering Division, Argonne National Laboratory , 9700 South Cass Avenue, Lemont, Illinois 60439, United States.
Lin X
LX
Chen
Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Robert P H
RP
Chang
Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Polyera Corporation, 8045 Lamon Avenue, Skokie, Illinois 60077, United States.
Antonio
A
Facchetti
Department of Materials Science and Engineering and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.|Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Tobin J
TJ
Marks