TY - JOUR
T1 - Novel wide-bandgap copolymer bearing alkylthio-thiophene-substituted benzodithiophene and methyl thiophene-3-carboxylate for highly stable fullerene-free simple polymer solar cells
AU - Park, Su Hong
AU - Park, Gi Eun
AU - Choi, Suna
AU - Park, Seo Yeon
AU - Park, Chang Geun
AU - Cho, Min Ju
AU - Choi, Dong Hoon
N1 - Funding Information:
This work was supported by National Research Foundation of Korea ( NRF2012R1A2A1A01008797 ) and by Key Research Institute Program ( NRF20100020209 ). We are grateful to the Pohang Accelerator Laboratory (Pohang, Korea) for allowing us to conduct the grazing incidence X-ray diffraction measurements. We also thank KBSI for allowing the use of their HRTEM instrument.
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2018/2
Y1 - 2018/2
N2 - We successfully synthesized a wide-bandgap p-type copolymer, 3MT-Th-S, bearing alkylthio-substituted benzodithiophene (BDT) as a donor and methyl-3-thiophenecarboxylate (3MT) as a weak electron acceptor. The electron affinity of the sulfur atom in the 2-ethylhexylthio side chains tethered to the thiophene units induces a low-lying highest occupied molecular orbital (HOMO) energy level in the corresponding polymer. 3MT-Th-S displays a strong absorption band from 400 to 600 nm, resulting in a relatively wide optical bandgap. Thin films of 3MT-Th-S exhibit a prominent face-on orientation in the out-of-plane profile, which might be a favorable orientation for moving charge carriers in the vertical direction in polymer solar cells (PSCs). Non-fullerene PSCs based on 3MT-Th-S as the donor and an n-type small molecule (ITIC, ITIC-Me, or IMIDT) were fabricated, and their performance was investigated in detail. Among the PSC devices bearing three different acceptors, the 3MT-Th-S:ITIC-based PSC exhibits the highest power conversion efficiency of 7.86% with a high short-circuit current density of 16.11 mA cm−2 and an open circuit voltage of 0.96 V. The high PCE values of PSC using the as-cast blend films of 3MT-Th-S and ITIC as an active layer without solvent additive are attributed to the low-lying HOMO level of the donor polymer, the complementary absorption behavior of the blend film, the face-on arrangement of polymer chains on the substrate, and the well-formed morphology of the binary blend film. These results clearly demonstrate that 3MT-Th-S is a promising wide-bandgap p-type polymer for high-performance fullerene-free simple PSCs.
AB - We successfully synthesized a wide-bandgap p-type copolymer, 3MT-Th-S, bearing alkylthio-substituted benzodithiophene (BDT) as a donor and methyl-3-thiophenecarboxylate (3MT) as a weak electron acceptor. The electron affinity of the sulfur atom in the 2-ethylhexylthio side chains tethered to the thiophene units induces a low-lying highest occupied molecular orbital (HOMO) energy level in the corresponding polymer. 3MT-Th-S displays a strong absorption band from 400 to 600 nm, resulting in a relatively wide optical bandgap. Thin films of 3MT-Th-S exhibit a prominent face-on orientation in the out-of-plane profile, which might be a favorable orientation for moving charge carriers in the vertical direction in polymer solar cells (PSCs). Non-fullerene PSCs based on 3MT-Th-S as the donor and an n-type small molecule (ITIC, ITIC-Me, or IMIDT) were fabricated, and their performance was investigated in detail. Among the PSC devices bearing three different acceptors, the 3MT-Th-S:ITIC-based PSC exhibits the highest power conversion efficiency of 7.86% with a high short-circuit current density of 16.11 mA cm−2 and an open circuit voltage of 0.96 V. The high PCE values of PSC using the as-cast blend films of 3MT-Th-S and ITIC as an active layer without solvent additive are attributed to the low-lying HOMO level of the donor polymer, the complementary absorption behavior of the blend film, the face-on arrangement of polymer chains on the substrate, and the well-formed morphology of the binary blend film. These results clearly demonstrate that 3MT-Th-S is a promising wide-bandgap p-type polymer for high-performance fullerene-free simple PSCs.
KW - Non-fullerene solar cells
KW - Polymer solar cells
KW - Simple process
KW - Wide bandgap
UR - http://www.scopus.com/inward/record.url?scp=85035765000&partnerID=8YFLogxK
U2 - 10.1016/j.orgel.2017.11.031
DO - 10.1016/j.orgel.2017.11.031
M3 - Article
AN - SCOPUS:85035765000
SN - 1566-1199
VL - 53
SP - 151
EP - 159
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
ER -