Extending 蟺-Conjugation System with Benzene: An Effective Method To Improve the Properties of Benzodithiophene-Based Polymer for Highly Efficient Organic Solar Cells

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• 作者：Jiuxing Wang ; Manjun Xiao ; Weichao Chen ; Meng Qiu ; Zhengkun Du ; Weiguo Zhu ; Shuguang Wen ; Ning Wang ; Renqiang Yang
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：November 25, 2014
• 年：2014
• 卷：47
• 期：22
• 页码：7823-7830
• 全文大小：436K
• ISSN：1520-5835

文摘

To obtain a polymer based on benzodithiophene (BDT) owning both a largely extended 蟺-conjugation system and a low-lying highest occupied molecular orbital (HOMO), a polymer (PBDTBzT-DTffBT) containing benzothienyl-substituted BDT is designed and synthesized. Compared with the polymer (PBDTT-DTffBT) based on thienyl-substituted BDT, PBDTBzT-DTffBT exhibits better thermal stabilities, red-shifted absorption spectra, and stronger intermolecular interactions. The HOMO and lowest unoccupied molecular orbital (LUMO) in PBDTBzT-DTffBT are decreased by 0.11 and 0.13 eV, respectively, which should be attributed to the contribution of the electron-withdrawing group benzene. Polymer solar cells (PSCs) based on PBDTBzT-DTffBT and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) exhibit a maximum power conversion efficiency (PCE) of 7.30% with a large open-circuit voltage of 0.90 V under AM 1.5G illumination (100 mW/cm²). The PCE is 36% higher than that of the PSCs derived from PBDTT-DTffBT. These findings provide a new approach to design high-performance conjugated polymers for efficient solution-processed PSCs.