Significantly improving the performance of polymer solar cells by the isomeric ending-group based small molecular acceptors: Insight into the isomerization. (December 2019)

• Record Type: Journal Article
• Authors: Luo, Zhenghui; Liu, Tao; Xiao, Yiqun; Yang, Tao; Chen, Zhanxiang; Zhang, Guangye; Zhong, Cheng; Ma, Ruijie; Chen, Yuzhong; Zou, Yang; Lu, Xinhui; Yan, He; Yang, Chuluo
• Is Part Of: Nano energy. Volume 66(2019)
• Publication Date: 2019-12
• Subjects: End-capping groups -- Small-molecule acceptors -- Polymer solar cells -- Power conversion efficiency -- Isomerization; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2019.104146
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Compared to benzene-fused end-capping groups (EGs), thiophene-fused EGs have some unique characteristics due to the non-centrosymmetric structure of the thiophene ring, which make them easy to form different types of isomers. Here, we develop three isomeric brominated thiophene-fused EGs, which are linked to the IDTT core to acquire three novel isomeric small-molecule acceptors (SMAs) named ITC-2Br, ITC-2Br1, and ITC-2Br2. From ITC-2Br to ITC-2Br1, the change of the bromine substituent group on the thiophene ring has only a minor impact on the physicochemical properties and photovoltaic performance. However, from ITC-2Br to ITC-2Br2, the change in the fused sites on the thiophene leads to dramatically modified absorption, energy levels, and photovoltaic performance. Theoretical simulations provide an in-depth understanding of the absorption and electrochemical differences among the three acceptors. Thanks to the favorable properties, the ITC-2Br2-based polymer solar cells (PSCs) yield a significantly higher power conversion efficiency (PCE) (13.1%) than the devices based on ITC-2Br (10.9%) and ITC-2Br1 (11.9%). From the ITC-2Br-, ITC-2Br1-to the ITC-2Br2-based devices, the J SC and FF exhibit a monotonic increase similar to the trend of PCE, which demonstrates the success of the isomerization strategy, highlighting its future prospects for the development of high-performance SMAs. Graphical abstract: Three isomeric ending-group based small molecular acceptors are designed to get deep insight into the ending-group engineering from theoretical simulation and experimental evidence. The ITC-2Br2-based polymer solar cells (PSCs) yields a significantly higher power energy efficiency (PCE) of 13.1% than those of the device base on ITC-2Br (10.9%) and ITC-2Br1 (11.9%). Image 1 Highlights: Three isomeric ending-group based small molecular acceptors were designed and synthesized. Theoretical simulation and experimental evidence were empolyed to get deep insight into the ending-group engineering. The ITC-2Br2-based device yields a higher PCE than those of the device based on ITC-2Br and ITC-2Br1. The success of isomerization strategy provides encouraging prospects for the development of high-performance SMAs.