Effect of Ring‐Fusion on Miscibility and Domain Purity: Key Factors Determining the Performance of PDI‐Based Nonfullerene Organic Solar Cells |
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Authors: | Huawei Hu Yunke Li Jianquan Zhang Zhengxing Peng Lik‐kuen Ma Jingming Xin Jiachen Huang Tingxuan Ma Kui Jiang Guangye Zhang Wei Ma Harald Ade He Yan |
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Affiliation: | 1. Department of Physics and Organic and Carbon Electronics Lab (ORaCEL), North Carolina State University, Raleigh, NC, USA;2. Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction and Energy Institute, The Hong Kong University of Science and Technology, Kowloon, Hong Kong;3. HKUST‐Shenzhen Research Institute, Nanshan, Shenzhen, China;4. State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, P. R. China |
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Abstract: | Compared to the rapid development of nonfullerene organic solar cells (OSCs) based on the state‐of‐the‐art indacenodithiophene (IDT)‐based small molecule acceptors (SMAs), the progress for perylene diimide (PDI)‐based electron acceptors has lagged behind owing to the lack of understanding on the structure–morphology–performance relationship of PDI SMAs. Given the ease of synthesis for PDIs and their high intrinsic electron mobility, it is crucial to identify key material parameters that influence the polymer:PDI blend morphology and to develop rational approaches for molecular design toward high‐performance PDI‐based SMAs. In this study, three pairs of PDI‐based SMAs with and without ring‐fusion are investigated and it is found that ring‐fusion and domain purity are the key structural and morphological factors determining the fill factors (FFs) and efficiencies of PDI‐based nonfullerene OSCs. This data shows that nonfullerene OSCs based on the ring‐fused PDI‐based SMAs exhibit much higher average domain purity and thus increased charge mobilities, which lead to enhanced FFs compared to those solar cells based on nonfused PDIs. This is explained by higher Florry Huggins interaction parameters as observed by melting point depression measurements. This study suggests that increasing repulsive molecular interactions to lower the miscibility between the polymer donor and PDI acceptor is the key to improve the FF and performance of PDI‐based devices. |
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Keywords: | average domain purity miscibility nonfullerene organic solar cells perylene diimide ring fusion |
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