Pushing the Efficiency of High Open-Circuit Voltage Binary Organic Solar Cells by Vertical Morphology Tuning

Guilong Cai; Zeng Chen; Xinxin Xia; Yuhao Li; Jiayu Wang; Heng Liu; PingPing Sun; Chao Li; Ruijie Ma; Yaoqiang Zhou; Weijie Chi; Jianqi Zhang; Haiming Zhu; Jianbin Xu; He Yan; Xiaowei Zhan; Xinhui Lu

doi:10.1002/advs.202200578

Pushing the Efficiency of High Open-Circuit Voltage Binary Organic Solar Cells by Vertical Morphology Tuning

Adv Sci (Weinh). 2022 May;9(14):e2200578. doi: 10.1002/advs.202200578. Epub 2022 Mar 21.

Authors

Guilong Cai¹, Zeng Chen², Xinxin Xia¹, Yuhao Li¹, Jiayu Wang³, Heng Liu¹, PingPing Sun⁴, Chao Li⁵, Ruijie Ma⁵, Yaoqiang Zhou⁶, Weijie Chi⁷, Jianqi Zhang⁸, Haiming Zhu², Jianbin Xu⁶, He Yan⁵, Xiaowei Zhan³, Xinhui Lu¹

Affiliations

¹ Department of Physics, The Chinese University of Hong Kong, New Territories, Hong Kong, 999077, China.
² State Key Laboratory of Modern Optical Instrumentation, Center for Chemistry of High-Performance & Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, 310030, China.
³ School of Materials Science and Engineering, Peking University, Beijing, 100871, China.
⁴ School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
⁵ Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research, Center for Tissue Restoration & Reconstruction, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Hong Kong, 999077, China.
⁶ Department of Electronic Engineering, The Chinese University of Hong Kong, New Territories, Hong Kong, 999077, China.
⁷ Fluorescence Research Group, Singapore University of Technology and Design, Singapore, 487372, Singapore.
⁸ CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.

Abstract

The tuning of vertical morphology is critical and challenging for organic solar cells (OSCs). In this work, a high open-circuit voltage (V_OC ) binary D18-Cl/L8-BO system is attained while maintaining the high short-circuit current (J_SC ) and fill factor (FF) by employing 1,4-diiodobenzene (DIB), a volatile solid additive. It is suggested that DIB can act as a linker between donor or/and acceptor molecules, which significantly modifies the active layer morphology. The overall crystalline packing of the donor and acceptor is enhanced, and the vertical domain sizes of phase separation are significantly decreased. All these morphological changes contribute to exciton dissociation, charge transport, and collection. Therefore, the best-performing device exhibits an efficiency of 18.7% with a V_OC of 0.922 V, a J_SC of 26.6 mA cm^-2 , and an FF of 75.6%. As far as it is known, the V_OC achieved here is by far the highest among the reported OSCs with efficiencies over 17%. This work demonstrates the high competence of solid additives with two iodine atoms to tune the morphology, particularly in the vertical direction, which can become a promising direction for future optimization of OSCs.

Keywords: open-circuit voltage; organic solar cells; power conversion efficiency; solid additive; vertical phase separation.

Abstract

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