TY - JOUR
T1 - Bithiopheneimide-dithienosilole/dithienogermole copolymers for efficient solar cells
T2 - Information from structure-property-device performance correlations and comparison to thieno[3,4- c ]pyrrole-4,6-Dione analogues
AU - Guo, Xugang
AU - Zhou, Nanjia
AU - Lou, Sylvia J.
AU - Hennek, Jonathan W.
AU - Ponce Ortiz, Rocío
AU - Butler, Melanie R.
AU - Boudreault, Pierre Luc T
AU - Strzalka, Joseph
AU - Morin, Pierre Olivier
AU - Leclerc, Mario
AU - López Navarrete, Juan T.
AU - Ratner, Mark A.
AU - Chen, Lin X.
AU - Chang, Robert P H
AU - Facchetti, Antonio
AU - Marks, Tobin J.
PY - 2012/11/7
Y1 - 2012/11/7
N2 - Rational creation of polymeric semiconductors from novel building blocks is critical to polymer solar cell (PSC) development. We report a new series of bithiopheneimide-based donor-acceptor copolymers for bulk-heterojunction (BHJ) PSCs. The bithiopheneimide electron-deficiency compresses polymer bandgaps and lowers the HOMOs-essential to maximize power conversion efficiency (PCE). While the dithiophene bridge progression R 2Si→R 2Ge minimally impacts bandgaps, it substantially alters the HOMO energies. Furthermore, imide N-substituent variation has negligible impact on polymer opto-electrical properties, but greatly affects solubility and microstructure. Grazing incidence wide-angle X-ray scattering (GIWAXS) indicates that branched N-alkyl substituents increased polymer π-π spacings vs linear N-alkyl substituents, and the dithienosilole-based PBTISi series exhibits more ordered packing than the dithienogermole-based PBTIGe analogues. Further insights into structure-property-device performance correlations are provided by a thieno[3,4-c]pyrrole-4,6-dione (TPD)-dithienosilole copolymer PTPDSi. DFT computation and optical spectroscopy show that the TPD-based polymers achieve greater subunit-subunit coplanarity via intramolecular (thienyl) S⋯O(carbonyl) interactions, and GIWAXS indicates that PBTISi-C8 has lower lamellar ordering, but closer π-π spacing than does the TPD-based analogue. Inverted BHJ solar cells using bithiopheneimide-based polymer as donor and PC 71BM as acceptor exhibit promising device performance with PCEs up to 6.41% and V oc > 0.80 V. In analogous cells, the TPD analogue exhibits 0.08 V higher V oc with an enhanced PCE of 6.83%, mainly attributable to the lower-lying HOMO induced by the higher imide group density. These results demonstrate the potential of BTI-based polymers for high-performance solar cells, and provide generalizable insights into structure-property relationships in TPD, BTI, and related polymer semiconductors.
AB - Rational creation of polymeric semiconductors from novel building blocks is critical to polymer solar cell (PSC) development. We report a new series of bithiopheneimide-based donor-acceptor copolymers for bulk-heterojunction (BHJ) PSCs. The bithiopheneimide electron-deficiency compresses polymer bandgaps and lowers the HOMOs-essential to maximize power conversion efficiency (PCE). While the dithiophene bridge progression R 2Si→R 2Ge minimally impacts bandgaps, it substantially alters the HOMO energies. Furthermore, imide N-substituent variation has negligible impact on polymer opto-electrical properties, but greatly affects solubility and microstructure. Grazing incidence wide-angle X-ray scattering (GIWAXS) indicates that branched N-alkyl substituents increased polymer π-π spacings vs linear N-alkyl substituents, and the dithienosilole-based PBTISi series exhibits more ordered packing than the dithienogermole-based PBTIGe analogues. Further insights into structure-property-device performance correlations are provided by a thieno[3,4-c]pyrrole-4,6-dione (TPD)-dithienosilole copolymer PTPDSi. DFT computation and optical spectroscopy show that the TPD-based polymers achieve greater subunit-subunit coplanarity via intramolecular (thienyl) S⋯O(carbonyl) interactions, and GIWAXS indicates that PBTISi-C8 has lower lamellar ordering, but closer π-π spacing than does the TPD-based analogue. Inverted BHJ solar cells using bithiopheneimide-based polymer as donor and PC 71BM as acceptor exhibit promising device performance with PCEs up to 6.41% and V oc > 0.80 V. In analogous cells, the TPD analogue exhibits 0.08 V higher V oc with an enhanced PCE of 6.83%, mainly attributable to the lower-lying HOMO induced by the higher imide group density. These results demonstrate the potential of BTI-based polymers for high-performance solar cells, and provide generalizable insights into structure-property relationships in TPD, BTI, and related polymer semiconductors.
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U2 - 10.1021/ja3081583
DO - 10.1021/ja3081583
M3 - Article
C2 - 23030837
AN - SCOPUS:84868592669
SN - 0002-7863
VL - 134
SP - 18427
EP - 18439
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 44
ER -