Bithiophene Imide-Based “Chemically Homologous” Active Layer Enables Efficient and Stable All-Polymer Solar Cells

Xinxi Yang; Henan Li; Mingqing Chen; Junyi Lu; Qingqing Bai; Jiaxu Che; Jong Bin Park; Suxiang Ma; Zhongxia Wang; Guangye Zhang; Junwu Chen; Han Young Woo; Dongdong Qin; Wei Wang; Li Niu; Huiliang Sun

doi:10.1002/cjoc.70456

Chinese Journal of Chemistry ›› 2026, Vol. 44 ›› Issue (8) :1123 -1133. DOI: 10.1002/cjoc.70456

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Bithiophene Imide-Based “Chemically Homologous” Active Layer Enables Efficient and Stable All-Polymer Solar Cells

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¹. Guangdong Engineering Technology Research Center for Photoelectric Sensing Materials & Devices, Guangzhou Key Laboratory of Sensing Materials & Devices, Center for Advanced Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou, Guangdong, 510006 China

². China School of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou, Jiangxi, 341000 China

³. State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, Guangdong, 510641 China

⁴. College of New Materials and New Energies, Shenzhen Technology University, Shenzhen, Guangdong, 518118 China

⁵. Department of Chemistry, Korea University, Seoul, 136-713 South Korea

⁶. Anhui Provincial Engineering Center for High Performance Biobased Nylons, Department of Materials and Chemistry, Anhui Agricultural University, Hefei, Anhui, 230036 China

⁷. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022 China

ccqindd@gzhu.edu.cn

wangw@gzhu.edu.cn

lniu@gzhu.edu.cn

Huiliang@gzhu.edu.cn

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Abstract

Precise control over the active layer morphology is critical for achieving high-performance all-polymer solar cells (all-PSCs). In this study, we introduce a fully “chemically homologous” strategy, in which a series of tailored solid additives, polymer donor, and polymer acceptor are constructed from the same bithiophene imide (BTI) building block. Among them, the B3 additive, which shares an identical side chain with the donor, guides the formation of an optimal fibrillar network morphology with enhanced structural order. This optimized microstructure facilitates efficient exciton dissociation and charge transport, yielding a remarkable power conversion efficiency (PCE) of 18.52%—significantly surpassing those of additive-free (14.54%) and non-homologous reference devices (<17%). Furthermore, this chemically coherent approach promotes ordered molecular packing, simultaneously suppressing molecular disorder and non-radiative energy loss, achieving a low energy loss (E_loss) of 0.509 eV and a high open-circuit voltage (V_OC) of 0.943 V. The B3-processed device also retains outstanding stability, maintaining over 97% of its initial PCE after 1240 h in a nitrogen atmosphere at room temperature. The chemically homologous paradigm demonstrated here provides crucial insights into morphology control and charge transport dynamics in all-polymer blends, offering a promising pathway toward highly efficient and stable organic photovoltaics.

Keywords

Chemically homologous / All-polymer solar cells / Bithiophene imide / Solid additive / Morphology control / Energy loss / Power conversion efficiency / Stability

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Xinxi Yang, Henan Li, Mingqing Chen, Junyi Lu, Qingqing Bai, Jiaxu Che, Jong Bin Park, Suxiang Ma, Zhongxia Wang, Guangye Zhang, Junwu Chen, Han Young Woo, Dongdong Qin, Wei Wang, Li Niu, Huiliang Sun. Bithiophene Imide-Based “Chemically Homologous” Active Layer Enables Efficient and Stable All-Polymer Solar Cells. Chinese Journal of Chemistry, 2026, 44 (8) : 1123-1133 DOI:10.1002/cjoc.70456