TY - JOUR
T1 - Performance, Morphology, and Charge Recombination Correlations in Ternary Squaraine Solar Cells
AU - Chen, Yao
AU - Yang, Lin
AU - Wu, Jianglin
AU - Wang, Gang
AU - Huang, Wei
AU - Melkonyan, Ferdinand
AU - Lu, Zhiyun
AU - Huang, Yan
AU - Marks, Tobin J.
AU - Facchetti, Antonio
N1 - Funding Information:
We acknowledge the financial support for this work from the National Natural Science Foundation of China (projects No. 51573108 and 21672156). T.J.M. and G.W. (materials characterization) acknowledge financial support from the Argonne-Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0001059. We thank AFOSR (FA9550-15-1-0044), the Northwestern University MRSEC (NSF DMR-1720139), and Flexterra Corp. for additional support of this research in the form of materials synthesis and facilities. This work made use of the J. B. Cohen X-ray Diffraction Facility, EPIC facility, Keck-II facility, and SPID facility of the NUANCE Center at Northwestern University, which received support from the MRSEC program (NSF DMR-1720139); the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois. A.F. thanks the Shenzhen Peacock Plan project (KQTD20140630110339343). Y.C. thanks the joint-Ph.D. program supported by the China Scholarship Council for fellowship.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/10/9
Y1 - 2018/10/9
N2 - Ternary bulk-heterojunction organic solar cells (BHJ-OSCs) are demonstrated by combining two squaraine donors (USQ3OH and IDPSQ) having complementary optical absorption and PC71BM as the acceptor. While the corresponding binary cells exhibit maximum power conversion efficiencies (PCEs) of 4.65% (IDPSQ binary) and 6.85% (USQ3OH binary), the ternary cells of weight composition IDPSQ:USQ3OH:PC71BM = 0.15:1.0:3.0 (15%TB, TB = ternary blend) exhibit a PCE of 7.20%, which is the highest known value to date for a squaraine OSC. Single crystals of both squaraines and space-charge-limited current (SCLC) measurements explain the efficiency difference between the binary cells. SCLC measurements and transmission electron microscopy imaging of the ternary devices indicate that the charge mobility slightly increases and the BHJ domain size optimizes for the 15%TB device vs that based on the USQ3OH blend. Grazing incidence wide-angle X-ray scattering data reveal that enhanced π-π stacking and larger correlation lengths can be achieved after thermal annealing of the ternary blend film. Charge recombination measurements demonstrate that IDPSQ can be incorporated into the blend without increasing charge recombination. Finally, flexible OSCs on PET (polyethylene terephthalate) with a PCE of ∼4.5% were fabricated. This study demonstrates that readily accessible squaraine cores represent a viable choice for the design of new organic solar cell donor materials.
AB - Ternary bulk-heterojunction organic solar cells (BHJ-OSCs) are demonstrated by combining two squaraine donors (USQ3OH and IDPSQ) having complementary optical absorption and PC71BM as the acceptor. While the corresponding binary cells exhibit maximum power conversion efficiencies (PCEs) of 4.65% (IDPSQ binary) and 6.85% (USQ3OH binary), the ternary cells of weight composition IDPSQ:USQ3OH:PC71BM = 0.15:1.0:3.0 (15%TB, TB = ternary blend) exhibit a PCE of 7.20%, which is the highest known value to date for a squaraine OSC. Single crystals of both squaraines and space-charge-limited current (SCLC) measurements explain the efficiency difference between the binary cells. SCLC measurements and transmission electron microscopy imaging of the ternary devices indicate that the charge mobility slightly increases and the BHJ domain size optimizes for the 15%TB device vs that based on the USQ3OH blend. Grazing incidence wide-angle X-ray scattering data reveal that enhanced π-π stacking and larger correlation lengths can be achieved after thermal annealing of the ternary blend film. Charge recombination measurements demonstrate that IDPSQ can be incorporated into the blend without increasing charge recombination. Finally, flexible OSCs on PET (polyethylene terephthalate) with a PCE of ∼4.5% were fabricated. This study demonstrates that readily accessible squaraine cores represent a viable choice for the design of new organic solar cell donor materials.
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U2 - 10.1021/acs.chemmater.8b02746
DO - 10.1021/acs.chemmater.8b02746
M3 - Article
AN - SCOPUS:85053692621
SN - 0897-4756
VL - 30
SP - 6810
EP - 6820
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 19
ER -