物理化学学报 >> 2019, Vol. 35 >> Issue (12): 13911391-1398.doi: 10.3866/PKU.WHXB201904037

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通过调节共轭聚合物侧链实现可绿色溶剂加工的非富勒烯太阳能电池

吴仪1,孔静宜1,秦云朋1,姚惠峰2,张少青1,*(),侯剑辉1,2   

  1. 1 北京科技大学化学与生物工程学院,北京 100083
    2 中国科学院化学研究所,北京 100190
  • 收稿日期:2019-04-08 录用日期:2019-05-15 发布日期:2019-05-23
  • 通讯作者: 张少青 E-mail:shaoqingz@ustb.edu.cn
  • 基金资助:
    国家自然科学基金(21704004);国家科技重大专项(2016YFC0700603);中央高校基本科研业务费专项资金(FRF-TP-17-009A1)

Realizing Green Solvent Processable Non-fullerene Organic Solar Cells by Modulating the Side Groups of Conjugated Polymers

Yi WU1,Jingyi KONG1,Yunpeng QIN1,Huifeng YAO2,Shaoqing ZHANG1,*(),Jianhui HOU1,2   

  1. 1 Department of Chemical and Biological Engineering, University of Science & Technology Beijing, Beijing 100083, P. R. China
    2 Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2019-04-08 Accepted:2019-05-15 Published:2019-05-23
  • Contact: Shaoqing ZHANG E-mail:shaoqingz@ustb.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21704004);the National Science and Technology Major Project of the Ministry of Science and Technology of China(2016YFC0700603);the Fundamental Research Funds for the Central Universities, China(FRF-TP-17-009A1)

摘要:

有机太阳能电池(OSC)经过长期的发展,其能量转换效率(PCE)已快速推进至14%–16%,基本接近可商业化应用的范围,但在目前所见报道的高效率OSC器件的制备过程中,活性层薄膜的加工大多采用氯苯、二氯苯、氯仿等毒性较高的含卤/芳香性试剂,此类试剂对环境及人类健康的危害非常高。在本工作中,我们基于已报道的高效率给体共轭聚合物PBDB-T,通过扩大共轭侧链结构与增长柔性烷基侧链的方式,合成了新型给体聚合物PBDB-DT。PBDB-DT中较长的柔性烷基侧链保证了其在低毒性溶剂四氢呋喃(THF)溶液中良好的溶解度,同时,扩大的共轭侧链也有效增强了其在THF中的溶液聚集作用,这一特性对于在非富勒烯型OSC器件中获得较好的光伏性能尤其重要。当采用非富勒烯小分子IT-M作为电子受体材料时,以THF为主溶剂加工的基于PBDB-DT:IT-M的OSC器件可以获得10.2%的能量转换效率。

关键词: 共轭聚合物, 非富勒烯受体, 有机太阳能电池, 绿色溶剂, 分子设计

Abstract:

Organic solar cells (OSCs) are a promising next-generation photovoltaic technology that can be used to harvest clean and renewable solar energy. OSCs are typically composed of donor:acceptor blends as photo-active materials. Compared to the conventional inorganic silicon solar cells, OSCs are suitable for large-scale production using roll-to-roll technology, promising low-cost and the potential to avoid environmental pollution. The last few years have witnessed the rapid development of OSCs. The power conversion efficiencies (PCEs) of OSCs have surpassed ~14%–16%, benefiting from the design of novel materials, optimization of blend morphology, and deep understanding of the charge generation mechanism. Currently, the most widely used processing solvents for preparing high-efficient OSCs are chlorinated or aromatic solvents including chlorobenzene, dichlorobenzene, and chloroform, which are highly detrimental to the environment and human health, and may not be utilized for future in industry. Thus, replacing these highly toxic solvents with environmentally friendly alternatives called "green solvents" is an important topic in OSC research. Herein, poly[(2, 6-(4, 8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1, 2-b:4, 5-b′]dithiophene)-co-(1, 3-di(5-thiophene-2-yl)-5, 7-bis(2-ethylhexyl)benzo[1, 2-c:4, 5-c′]dithiophene-4, 8-dione)] (PBDB-T) was used as a reference material to design and synthesize a novel conjugated polymer (PBDB-DT) by extending the alkyl side chains and enlarging the conjugated side groups. The thermal stability of the polymer donor was examined via thermogravimetric analysis, showing that the polymers exhibit very good stability at > 400 ℃. Importantly, PBDB-DT exhibits good solubility in low-toxic solvent tetrahydrofuran (THF) due to its longer alkyl side chains, and shows a strong aggregation effect in THF due to the larger conjugated side groups. A favorable PCE of 10.2% was achieved for the THF-processed PBDB-DT:IT-M based OSC device. In contrast, PBDB-T has limited solubility in THF. The solar cell device based on PBDB-T:IT-M delivered a moderate PCE of 6.41%. The investigation of blend morphology via atomic force microscope suggested that the PBDB-DT:IT-M has a smooth surface, which is favorable for charge generation and transport. These results demonstrate that molecular optimization is a promising strategy to modulate the solubility and achieve high efficiency for organic photovoltaic materials processed using green solvents.

Key words: Conjugated polymer, Non-fullerene acceptor, Organic solar cell, Green solvent, Molecular design

MSC2000: 

  • O646