Solution-Processable Organic Molecule for High-Performance Organic Solar Cells with Low Acceptor Content

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• 作者：Kun Wang ; Bing Guo ; Zhuo Xu ; Xia Guo ; Maojie Zhang ; Yongfang Li
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：November 11, 2015
• 年：2015
• 卷：7
• 期：44
• 页码：24686-24693
• 全文大小：546K
• ISSN：1944-8252

文摘

A new planar D2-A-D1-A-D2 structured organic molecule with bithienyl benzodithiophene (BDT) as central donor unit D1 and fluorine-substituted benzothiadiazole (BTF) as acceptor unit and alkyl-dithiophene as end group and donor unit D2, BDT-BTF, was designed and synthesized for the application as donor material in organic solar cells (OSCs). BDT-BTF shows a broad absorption in visible region, suitable highest occupied molecular orbital energy level of 鈭?.20 eV, and high hole mobility of 1.07 脳 10^鈥? cm²/(V s), benefitted from its high coplanarity and strong crystallinity. The OSCs based on BDT-BTF as donor (D) and PC₇₁BM as acceptor (A) at a D/A weight ratio of 3:1 without any extra treatment exhibit high photovoltaic performance with V_oc of 0.85 V, J_sc of 10.48 mA/cm², FF of 0.66, and PCE of 5.88%. The morphological study by transmission electron microscopy reveals that the blend of BDT-BTF and PC₇₁BM (3:1, w/w) possesses an appropriate interpenetrating D/A network for the exciton separation and charge carrier transport, which agrees well with the good device performance. The optimized D/A weight ratio of 3:1 is the lowest acceptor content in the active layer reported so far for the high-performance OSCs, and the organic molecules with the molecular structure like BDT-BTF could be promising high-performance donor materials in solution-processable OSCs.