Using combinatory photoactive blends is a promising approach to achieve high power conversion efficiency in ternary organic photovoltaics. However, the fundamental challenge of how to manipulate the morphology of multiple components and correlate structure details via device performance has not been well addressed. Achieving an ideal morphology that simultaneously enhances charge generation and transport and reduces voltage loss is an imperative avenue to improve device efficiency. Here, we achieve a high power conversion efficiency of 13.20 ± 0.25% for ternary solar cells by using a combination of small molecules with both fullerene and non-fullerene acceptors, which form a hierarchical morphology consisting of a PCBM transporting highway and an intricate non-fullerene phase-separated pathway network. Carrier generation and transport find an optimized balance, and voltage loss is simultaneously reduced. Such a morphology fully utilizes the individual advantages of both fullerene and non-fullerene acceptors, demonstrating their indispensability in organic photovoltaics.
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The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.
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We thank the National Basic Research Program of China (Program 973) (No. 2014CB643502), the National Key R&D Program of China (2017YFA0204700), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB12010200) and the National Natural Science Foundation of China (21572234, 21661132006) for their financial support. Portions of this research were carried out at beamlines 7.3.3 and 22.214.171.124 at the Advanced Light Source and Molecular Foundry at the Lawrence Berkeley National Laboratory, which was supported by the Department of Energy (DOE), Office of Science and Office of Basic Energy Sciences. Y.J. and F.Z. acknowledge financial support from the Swedish Research Council (VR621-2013-5561), the Swedish Government Strategic Research Area in Material Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No 200900971) and the China Scholarship Council (CSC201606920028).
The authors declare no competing interests.
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Zhou, Z., Xu, S., Song, J. et al. High-efficiency small-molecule ternary solar cells with a hierarchical morphology enabled by synergizing fullerene and non-fullerene acceptors. Nat Energy 3, 952–959 (2018). https://doi.org/10.1038/s41560-018-0234-9
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