Synthesis of 5H-Dithieno[3,2-b:2鈥?3鈥?d]pyran as an Electron-Rich Building Block for Donor鈥揂cceptor Type Low-Bandgap Polymers

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• 作者：Letian Dou ; Chun-Chao Chen ; Ken Yoshimura ; Kenichiro Ohya ; Wei-Hsuan Chang ; Jing Gao ; Yongsheng Liu ; Eric Richard ; Yang Yang
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：May 14, 2013
• 年：2013
• 卷：46
• 期：9
• 页码：3384-3390
• 全文大小：416K
• 年卷期：v.46,no.9(May 14, 2013)
• ISSN：1520-5835

文摘

We describe the detailed synthesis and characterization of an electron-rich building block, dithienopyran (DTP), and its application as a donor unit in low-bandgap conjugated polymers. The electron-donating property of the DTP unit was found to be the strongest among the most frequently used donor units such as benzodithiophene (BDT) or cyclopentadithiophene (CPDT) units. When the DTP unit was polymerized with the strongly electron-deficient difluorobenzothiadiazole (DFBT) unit, a regiorandom polymer (PDTP鈥揇FBT, bandgap = 1.38 eV) was obtained. For comparison with the DTP unit, polymers containing alternating benzodithiophene (BDT) or cyclopentadithiophene (CPDT) units and the DFBT unit were synthesized (PBDT鈥揇FBT and PCPDT鈥揇FBT). We found that the DTP based polymer PDTP鈥揇FBT shows significantly improved solubility and processability compared to the BDT or CPDT based polymers. Consequently, very high molecular weight and soluble PDTP鈥揇FBT can be obtained with less bulky side chains. Interestingly, PDTP鈥揇FBT shows excellent performance in bulk-heterojunction solar cells with power conversion efficiencies reaching 8.0%, which is significantly higher than PBDT鈥揇FBT and PCPDT鈥揇FBT based devices. This study demonstrates that DTP is a promising building block for high-performance solar cell materials.