Improvement of Photovoltaic Performance of Polymer Solar Cells by Rational Molecular Optimization of Organic Molecule Acceptors |
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Authors: | Xiaojun Li Jia Yao Indunil Angunawela Chenkai Sun Lingwei Xue Alexander Liebman‐Pelaez Chenhui Zhu Chunhe Yang Zhi‐Guo Zhang Harald Ade Yongfang Li |
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Institution: | 1. CAS Research/Education Center for Excellence in Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China;2. School of Chemical Science, University of Chinese Academy of Sciences, Beijing, China;3. Department of Chemistry, School of Science, Beijing JiaoTong University, Beijing, China;4. Department of Physics and Organic and Carbon Electronics Lab, North Carolina State University, Raleigh, NC, USA;5. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA;6. Laboratory of Advanced Optoelectronic Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu, China |
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Abstract: | Two n‐type organic semiconductor (n‐OS) small molecules m‐ITIC‐2F and m‐ITIC‐4F with fluorinated 2‐(2,3‐dihydro‐3‐oxo‐1H‐inden‐1‐ylidene)propanedinitrile (IC) terminal moieties are prepared, for the application as an acceptor in polymer solar cells (PSCs), to further improve the photovoltaic performance of the n‐OS acceptor 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene) indanone) ‐5,5,11,11‐tetrakis(3‐hexylphenyl)‐dithieno2,3‐d:2′,3′‐d′]‐sindaceno1,2‐b:5,6‐b′]‐dithiophene (m‐ITIC). Compared to m‐ITIC, these two new acceptors show redshifted absorption, higher molecular packing order, and improved electron mobilities. The power conversion efficiencies (PCE) of the as‐cast PSCs with m‐ITIC‐2F or m‐ITIC‐4F as an acceptor and a low‐cost donor–acceptor (D–A) copolymer PTQ10 as a donor reach 11.57% and 11.64%, respectively, which are among the highest efficiency for the as‐cast PSCs so far. Furthermore, after thermal annealing treatment, improved molecular packing and enhanced phase separation are observed, and the higher PCE of 12.53% is achieved for both PSCs based on the two acceptors. The respective and unique advantage with the intrinsic high degree of order, molecular packing, and electron mobilities of these two acceptors will be suitable to match with different p‐type organic semiconductor donors for higher PCE values, which provide a great potential for the PSCs commercialization in the near future. These results indicate that rational molecular structure optimization is of great importance to further improve photovoltaic properties of the photovoltaic materials. |
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Keywords: | molecular structure optimization n‐type organic semiconductors organic molecule acceptors polymer solar cells power conversion efficiencies |
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