Selenium Substitution in Bithiophene Imide Polymer Semiconductors Enables High-Performance n-Type Organic Thermoelectric |
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| Authors: | Jianfeng Li Min Liu Kun Yang Yimei Wang Junwei Wang Zhicai Chen Kui Feng Dong Wang Jianqi Zhang Yongchun Li Han Guo Zhixiang Wei Xugang Guo |
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| Institution: | 1. Department of Materials Science and Engineering, Southern University of Science and Technology (SUSTech), No. 1088, Xueyuan Road, Shenzhen, Guangdong, 518055 China;2. School of Chemistry and Materials Engineering, Huizhou University, Huizhou, Guangdong, 516001 China;3. State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan, 410082 China;4. Shenzhen Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen, 518055 China;5. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, 100190 China |
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| Abstract: | Designing n-type polymers with high electrical conductivity remains a major challenge for organic thermoelectrics (OTEs). Herein, by devising a novel selenophene-based electron-deficient building block, the pronounced advantages of selenium substitution in simultaneously enabling advanced n-type polymers is demonstrated with high mobility (≈2 orders of magnitude higher versus their sulfur-based analogues due to both intensified intra- and inter-chain interactions) and much improved n-doping efficiency (enabled by the largely lowered LUMO level with a ≈0.2 eV margin) of the resulting polymers. Via side chain optimization and donor engineering, the selenium-substituted polymer, f-BSeI2TEG-FT, achieves a highest conductivity of 103.5 S cm−1 and power factor of 70.1 µW m−1 K−2, which are among the highest values reported in literature for n-type polymers, and f-BSeI2TEG-FT greatly outperformed the sulfur-based analogue polymer by 40% conductivity increase. These results demonstrate that selenium substitution is a very effective strategy for improving n-type performance and provide important structure-property correlations for developing high-performing n-type OTE materials. |
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| Keywords: | electrical conductivity n-doping organic thermoelectric polymer semiconductors selenium substitutions |
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