近十年来,有机聚合物太阳能电池取得了长足的发展。通用的异质结聚合物太阳能电池以溶液加工的聚合物和富勒烯衍生物(PCBM)的混合薄膜为活性层,目前这类太阳能电池的能量转换效率(PCE)已经超过了11%。然而PCBM具有一些先天的缺陷,比如:弱的吸收、高的价格和差的形貌稳定性。为了克服这些缺点,近5年来,关于全聚合物太阳能电池的研究非常活跃。制备高效率的全聚合物太阳能电池需要吸收互补、能带匹配、高分子量的p型和n型聚合物。相比p型聚合物的蓬勃发展,n型聚合物的种类目前十分有限。直到最近几年,一些高电子迁移率、高吸收系数的n型聚合物被不断的报道出来。目前,最通用n型聚合物是基于NDI和联噻吩的交替共聚物N2200,与高效率的p型聚合物PTB7-Th配合,这类全聚合物太阳能电池最高的能量转换效率在6%左右。然而聚合物N2200具有刚性较大的分子主链,在混合薄膜中容易形成大的结晶,从而很难获得令人满意的混合薄膜形貌,降低了电池中激子分离和传输的效率。
Figure 1. Chemical structures of donor and acceptor polymers
为了解决这一问题,瑞典查尔姆斯理工大学(Chalmers University of Technology)Ergang Wang副教授团队与埃因霍温理工大学(Eindhoven University of Technology)的René A. J. Janssen教授合作,通过在N2200主链中引入了少量的单一噻吩,合成了一系列NDI-联噻吩-噻吩的共聚物。其中,含有10%噻吩的共聚物PNDI-T10具有更高的分子量、更柔性的聚合物主链和低的结晶度,其分子链在制备器件的过程中对于溶剂退火更敏感。因此,基于PTB7-Th:PNDI-T10的全聚合物太阳能电池获得了7.6%的能量转换效率,几乎是PTB7-Th:N2200电池效率的两倍。作为太阳能电池的重要指标之一,其填充因子(FF)达到了0.71,是目前全聚合物太阳能电池中的最高值。本文通过一种简单的方法,合成了高效率的n型聚合物材料,制备了高效率的全聚合物太阳能电池,显示了全聚合物太阳能电池的巨大潜力。
Figure 2. J−V characteristics and performance of PTB7-Th:PNDI-T10 (1:1 w:w) and PTB7-Th:N2200 (1:1 w:w) solar cells
这一成果发表在Journal of the American Chemical Society上,文章的第一作者是瑞典查尔姆斯理工大学博士研究生Zhaojun Li,通讯作者是查尔姆斯理工大学Xiaofeng Xu博士、Ergang Wang副教授和埃因霍温理工大学的René A. J. Janssen教授。
该论文作者为:Zhaojun Li, Xiaofeng Xu*, Wei Zhang, Xiangyi Meng, Wei Ma, Arkady Yartsev, Olle Inganäs, Mats. R. Andersson, René A. J. Janssen*, and Ergang Wang*
原文(扫描或长按二维码,识别后直达原文页面,或点此查看原文):
High Performance All-Polymer Solar Cells by Synergistic Effects of Fine-Tuned Crystallinity and Solvent Annealing
J. Am. Chem. Soc., 2016, 138, 10935-10944, DOI: 10.1021/jacs.6b04822
Prof. Ergang Wang简介
Ergang Wang was appointed as an Associate Professor in the Department of Chemistry and Chemical Engineering in 2016. He has been an Assistant Professor in 2012-2016. Previously, he has been a postdoc fellow in the same department in 2008-2011. He obtained his Ph.D degree in Materials Science in 2008 and Docentship in 2015.
The focus of his research is on the development of new conjugated polymers and Graphene-like materials. The main applications of the materials are organic solar cells, photodetectors, light-emitting diodes and field effect transistors. Moreover, he has broad interests in flow battery, ferroelectric materials and thermoelectrics.
He has published more than 80 scientific papers with total citation over 3800 times.
Dr. Xiaofeng Xu 简介
Dr. Xiaofeng Xu is a post-doc at the Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Sweden. He obtained his Ph.D from South China University of Technology in 2011. During 2011-2014, he worked as a post-doc at School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore. His current research focuses on developing high-performance and stable all-polymer solar cells via rational adjustment of both donor and acceptor polymers.
He has published more than 25 scientific papers with total citation over 550 times.