Hybrid Cycloalkyl-Alkyl Chain-Based Symmetric/Asymmetric Acceptors with Optimized Crystal Packing and Interfacial Exciton Properties for Efficient Organic Solar Cells

Cong Xiao; Xunchang Wang; Tian Zhong; Ruixue Zhou; Xufan Zheng; Yirui Liu; Tianyu Hu; Yixuan Luo; Fengbo Sun; Biao Xiao; Zhitian Liu; Chunming Yang; Renqiang Yang

doi:10.1002/advs.202206580

Hybrid Cycloalkyl-Alkyl Chain-Based Symmetric/Asymmetric Acceptors with Optimized Crystal Packing and Interfacial Exciton Properties for Efficient Organic Solar Cells

Adv Sci (Weinh). 2023 Mar;10(7):e2206580. doi: 10.1002/advs.202206580. Epub 2023 Jan 2.

Authors

Cong Xiao¹, Xunchang Wang^{1

2}, Tian Zhong¹, Ruixue Zhou¹, Xufan Zheng¹, Yirui Liu¹, Tianyu Hu¹, Yixuan Luo³, Fengbo Sun³, Biao Xiao¹, Zhitian Liu³, Chunming Yang⁴, Renqiang Yang¹

Affiliations

¹ Key Laboratory of Optoelectronic Chemical Materials and Devices (Ministry of Education), School of Optoelectronic Materials and Technology, Jianghan University, Wuhan, 430056, China.
² State Key Laboratory of Fine Blasting, Jianghan University, Wuhan, 430056, China.
³ Hubei Engineering Technology Research Center of Optoelectronic and New Energy Materials, Wuhan Institute of Technology, Wuhan, 430205, China.
⁴ Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204, China.

Abstract

Hybrid cycloalkyl-alkyl side chains are considered a unique composite side-chain system for the construction of novel organic semiconductor materials. However, there is a lack of fundamental understanding of the variations in the single-crystal structures as well as the optoelectronic and energetic properties generated by the introduction of hybrid side chains in electron acceptors. Herein, symmetric/asymmetric acceptors (Y-C10ch and A-C10ch) bearing bilateral and unilateral 10-cyclohexyldecyl are designed, synthesized, and compared with the symmetric acceptor 2,2'-((2Z,2'Z)-((12,13-bis(2-butyloctyl)-3,9 bis(ethylhexyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″':4',5']thieno[2',3':4,5] pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10- diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (L8-BO). The stepwise introduction of 10-cyclohexyldecyl side chains decreases the optical bandgap, deepens the energy level, and enables the acceptor molecules to pack closely in a regular manner. Crystallographic analysis demonstrates that the 10-cyclohexyldecyl chain endows the acceptor with a more planar skeleton and enforces more compact 3D network packing, resulting in an active layer with higher domain purity. Moreover, the 10-cyclohexyldecyl chain affects the donor/acceptor interfacial energetics and accelerates exciton dissociation, enabling a power conversion efficiency (PCE) of >18% in the 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6) (PM6):A-C10ch-based organic solar cells (OSCs). Importantly, the incorporation of Y-C10ch as the third component of the PM6:L8-BO blend results in a higher PCE of 19.1%. The superior molecular packing behavior of the 10-cyclohexyldecyl side chain is highlighted here for the fabrication of high-performance OSCs.

Keywords: asymmetric small molecule acceptors; crystal packing; organic solar cells; side-chain engineering.

Abstract

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