Issue

Vol. 18 (2026)

Asymmetric Side-Group Engineering of Nonfused Ring Electron Acceptors for High-Efficiency Thick-Film Organic Solar Cells

https://doi.org/10.1007/s40820-025-01905-y
Dawei Li
Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
Nan Wei
Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
Ya‑Nan Chen
College of Textiles and Clothing, State Key Laboratory of Bio‑Fibers and Eco‑Textiles, Qingdao University, Qingdao 266071, People’s Republic of China
Xiaodong Wang
College of Textiles and Clothing, State Key Laboratory of Bio‑Fibers and Eco‑Textiles, Qingdao University, Qingdao 266071, People’s Republic of China
Xu Han
Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, People’s Republic of China
Ziqing Bian
Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
Xinyuan Zhang
Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
Zhe Zhang
Laboratory of Eco‑environmental Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, People’s Republic of China
Wenkai Zhang
Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, People’s Republic of China
Xinjun Xu
Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
Cuihong Li
Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
Yahui Liu
College of Textiles and Clothing, State Key Laboratory of Bio‑Fibers and Eco‑Textiles, Qingdao University, Qingdao 266071, People’s Republic of China
Hao Lu
College of Materials Science and Engineering, Qingdao University, Qingdao 266071, People’s Republic of China
Zhishan Bo
Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China

Corresponding Author: Zhishan Bo

zsbo@bnu.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 81

Abstract

A nonfused ring electron acceptor (NFREA), designated as TT-Ph-C6, has been synthesized with the aim of enhancing the power conversion efficiency (PCE) of organic solar cells (OSCs). By integrating asymmetric phenylalkylamino side groups, TT-Ph-C6 demonstrates excellent solubility and its crystal structure exhibits compact packing structures with a three-dimensional molecular stacking network. These structural attributes markedly promote exciton diffusion and charge carrier mobility, particularly advantageous for the fabrication of thick-film devices. TT-Ph-C6-based devices have attained a PCE of 18.01% at a film thickness of 100 nm, and even at a film thickness of 300 nm, the PCE remains at 14.64%, surpassing that of devices based on 2BTh-2F. These remarkable properties position TT-Ph-C6 as a highly promising NFREA material for boosting the efficiency of OSCs.


Highlights:
1 The asymmetric side-group strategy was employed to develop a nonfused ring electron acceptor, designated as TT-Ph-C6, exhibiting enhanced solubility and three-dimensional molecular stacking.
2 Strong π–π interactions optimized blend film morphology, enabling TT-Ph-C6-based devices to achieve a power conversion efficiency (PCE) of 18.01% and FF of 80.10%, surpassing the 16.78% PCE of symmetric-chain 2BTh-2F.
3 Extended exciton diffusion lengths and accelerated dissociation further endowed TT-Ph-C6 with exceptional thick-film tolerance, delivering 15.18% PCE at 200 nm and 14.64% at 300 nm—among the highest efficiencies reported for non-fused acceptors.

Keywords

Organic solar cells Nonfused ring electron acceptors Asymmetric Power conversion efficiency
Li, Dawei, Nan Wei, Ya‑Nan Chen, Xiaodong Wang, Xu Han, Ziqing Bian, Xinyuan Zhang, Zhe Zhang, Wenkai Zhang, Xinjun Xu, Cuihong Li, Yahui Liu, Hao Lu, and Zhishan Bo. 2025. “Asymmetric Side-Group Engineering of Nonfused Ring Electron Acceptors for High-Efficiency Thick-Film Organic Solar Cells”. Nano-Micro Letters 18 (November):81. https://doi.org/10.1007/s40820-025-01905-y.
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