Dual-Additive-Driven Morphology Optimization for Solvent-Annealing-Free All-Small-Molecule Organic Solar Cells |
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| Authors: | Heng Liu Yuang Fu Zeng Chen Jiayu Wang Jiehao Fu Yuhao Li Guilong Cai Chun-Jen Su U-Ser Jeng Haiming Zhu Gang Li Xinhui Lu |
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| Affiliation: | 1. Department of Physics, The Chinese University of Hong Kong, New Territories, Hong Kong, 999077 China;2. State Key Laboratory of Modern Optical Instrumentation Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, 310030 China;3. Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hung Hum, Kowloon, Hong Kong, 999077 China;4. Spallation Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan, 523803 China;5. Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, No. 1 Zhongguancun North Second Street, Haidian District, Beijing, 100190 China;6. National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu, 30076 Taiwan
Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 30013 Taiwan |
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| Abstract: | All-small-molecule organic solar cells (ASM-OSCs), which consist of small-molecule donors and acceptors, have recently been studied extensively to eliminate the batch-to-batch variation from polymer-based donor or acceptor. On the other hand, the control of their active layer morphology is more challenging due to the similar chemical structure and miscibility of small-molecule donor and small-molecule accepter. Hence, this study develops a dual-additive-driven morphology optimization method for ASM-OSCs based on BTR-Cl:Y6. One solid additive – 1,4-diiodobenzene (DIB) and one liquid additive – diiodomethane (DIM) are selected, making use of their distinct interaction mechanisms with Y6 and BTR-Cl. It is found that DIB can form a eutectic phase with Y6, which can increase the intermolecular interactions and modulate the acceptor phase separation, while the simultaneous volatilization of DIM suppresses the over-aggregation of BTR-Cl during the film casting process. As a result of the synergistic morphology tuning, the optimized device delivers a power conversion efficiency (PCE) as high as 15.2%, among the highest PCE reported to date for binary ASM-OSCs without solvent annealing treatment. This work demonstrates the potential of morphology tuning via the incorporation of dual additives into ASM-OSCs, enabling them to achieve comparable efficiencies to those of conventional polymer/small-molecule based OSCs. |
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| Keywords: | all-small-molecule organic solar cells capacitance spectroscopy femtosecond transient absorption spectroscopy x-ray scattering |
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