Efficient Inverted Organic Solar Cells Based on a Fullerene Derivative-Modified Transparent Cathode

Yifan Wang; Hailin Cong; Bing Yu; Zhiguo Zhang; Xiaowei Zhan

doi:10.3390/ma10091064

Efficient Inverted Organic Solar Cells Based on a Fullerene Derivative-Modified Transparent Cathode

Materials (Basel). 2017 Sep 11;10(9):1064. doi: 10.3390/ma10091064.

Authors

Yifan Wang^{1

2}, Hailin Cong^{3

4}, Bing Yu^{5

6}, Zhiguo Zhang⁷, Xiaowei Zhan⁸

Affiliations

¹ Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071, China. wangyifan@qdu.edu.cn.
² Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, College of Materials Science and Engineering, Qingdao University, Qingdao 266071, China. wangyifan@qdu.edu.cn.
³ Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071, China. hailincong@yahoo.com.
⁴ Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, College of Materials Science and Engineering, Qingdao University, Qingdao 266071, China. hailincong@yahoo.com.
⁵ Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, Qingdao University, Qingdao 266071, China. yubingqdu@yahoo.com.
⁶ Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, College of Materials Science and Engineering, Qingdao University, Qingdao 266071, China. yubingqdu@yahoo.com.
⁷ Beijing National Laboratory for Molecular Sciences and Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. zgzhangwhu@iccas.ac.cn.
⁸ Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China. xwzhan@pku.edu.cn.

Abstract

Indium tin oxide (ITO) is a transparent conductive material which is extensively used in organic solar cells (OSCs) as electrodes. In inverted OSCs, ITO is usually employed as a cathode, which should be modified by cathode buffer layers (CBLs) to achieve better contact with the active layers. In this paper, an amine group functionalized fullerene derivative (DMAPA-C₆₀) is used as a CBL to modify the transparent cathode ITO in inverted OSCs based on PTB7 as a donor and PC₇₁BM as an acceptor. Compared with traditional ZnO CBL, DMAPA-C₆₀ exhibited comparable transmittance. OSCs based on DMAPA-C₆₀ show much better device performance compared with their ZnO counterparts (power conversion efficiencies (PCEs) improved from 6.24 to 7.43%). This is mainly because a better contact between the DMAPA-C₆₀ modified ITO and the active layer is formed, which leads to better electron transport and collection. Nanoscale morphologies also demonstrate that the surface of DMAPA-C₆₀-modified ITO is plainer than the ZnO counterparts, which also leads to the better device performance.

Keywords: ZnO; cathode buffer layer (CBL); fullerene derivative; organic solar cell (OSC); transparent conducting material.