Enhancement of Organic Photovoltaic Efficiency via Nanomorphology Control using Conjugated Polymers Incorporating Fullerene Compatible Side-Chains

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• 作者：Sungmin Park ; Dongkyun Seo ; Tae In Ryu ; Gukil Ahn ; Kyungwon Kwak ; Hyunjung Kim ; Cheol Hong Cheon ; Nam-Gyu Park ; BongSoo Kim ; Min Jae Ko ; Doh-Kwon Lee ; Jin Young Kim ; Honggon Kim ; Hae Jung Son
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：January 27, 2015
• 年：2015
• 卷：48
• 期：2
• 页码：337-345
• 全文大小：596K
• ISSN：1520-5835

文摘

We present controls of nanomorphology of polymer:fullerene BHJ films via synthesis of a series of push鈥損ull-type copolymers with various molar percentages of side chains terminated with o-dichlorobenzyl (DCBZ) groups. As the molar percentage of the DCBZ-containing repeat units increases, the miscibility of the polymers in the series with PC71BM increases with respect to that of the polymer (PTBBO) that does not contain DCBZ. In the optimal film morphology, which consists of a polymer containing 25 mol % DCBZ-terminated side chains in the electron-pull unit (PTBDCB25), the polymer/PC₇₁BM interface area is sufficiently large for efficient charge separation and percolated pathways is present for efficient charge carrier transport. In contrast, the BHJ film prepared from PTBBO has smaller interfaces and larger PC₇₁BM aggregates. Furthermore, the intermolecular interaction between PC₇₁BM and DCBZ induced changes in the PC₇₁BM鈥檚 electronic structure at the polymer:PC₇₁BM interface, resulting in an increase of the PC₇₁BM鈥檚 LUMO level and thereby the improved open-circuit voltage. As a result, the BHJ solar cell device fabricated with PTBDCB25 exhibits significantly improved performance with a PCE of 8.30%, whereas the PCE of PTBBO is 6.90%.