Enhanced open-circuit voltage in methoxyl substituted benzodithiophene-based polymer solar cells
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- 作者：Xiaonan Xue ; Tao Liu ; Xiangyi Meng ; Xiaobo Sun ; Lijun Huo…
- 关键词：polymer solar cell ; conjugated polymer ; HOMO ; open ; circuit voltage ; power conversion efficiency
- 刊名：Science China Chemistry
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：60
- 期：2
- 页码：243-250
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry/Food Science, general;
- 出版者：Science China Press
- ISSN：1869-1870
- 卷排序：60
文摘
The open-circuit voltage (Voc) is one of the important parameters that influence the power conversion efficiency (PCE) of polymer solar cells. Its value is mainly determined by the energy level offset between the highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor. Therefore, decreasing the HOMO value of the polymer could lead to a high Voc and thus increasing the cell efficiency. Here we report a facile way to lower the polymer HOMO energy level by using methoxyl substituted-benzodithiophene (BDT) unit. The polymer with the methoxyl functionl group (POBDT(S)-T1) exhibited a HOMO value of–5.65 eV, which is deeper than that (–5.52 eV) of polymer without methoxyl unit (PBDT(S)-T1). As a result, POBDT(S)-T1-based solar cells show a high Voc of 0.98 V and PCE of 9.2%. In contrast, PBDT(S)-T1-based devices show a relatively lower Voc of 0.89 V and a moderate PCE of 7.4%. The results suggest that the involvement of methoxyl group into conjugated copolymers can efficiencly lower their HOMO energy levels.