Suppressing Kinetic Aggregation of Non‐Fullerene Acceptor via Versatile Alloy States Enables High‐Efficiency and Stable Ternary Polymer Solar Cells. (3rd March 2021)

• Record Type: Journal Article
• Authors: Zhang, Kang‐Ning; Guo, Jia‐Jia; Zhang, Liu‐Jiang; Qin, Chao‐Chao; Yin, Hang; Gao, Xing‐Yu; Hao, Xiao‐Tao
• Is Part Of: Advanced functional materials. Volume 31:Number 20(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-03
• Subjects: alloy‐like model -- molecular aggregation -- non‐fullerene acceptors -- non‐radiative defect trapping -- organic solar cells; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202100316
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Despite considerable advances devoted to improving the operational stability of organic solar cells (OSCs), the metastable morphology degradation remains a challenging obstacle for their practical application. Herein, the stabilizing function of the alloy states in the photoactive layer from the perspective of controlling the aggregation characteristics of non‐fullerene acceptors (NFAs), is revealed. The alloy‐like model is adopted separately into host donor and acceptor materials of the state‐of‐the‐art binary PM6:BTP‐4Cl blend with the self‐stable polymer acceptor PDI‐2T and small molecule donor DRCN5T as the third components, delivering the simultaneously enhanced photovoltaic efficiency and storage stability. In such ternary systems, two separate arguments can rationalize their operating principles: (1) the acceptor alloys strengthen the conformational rigidity of BTP‐4Cl molecules to restrain the intramolecular vibrations for rapid relaxation of high‐energy excited states to stabilize BTP‐4Cl acceptor. (2) The donor alloys optimize the fibril network microstructure of PM6 polymer to restrict the kinetic diffusion and aggregation of BTP‐4Cl molecules. According to the superior morphological stability, non‐radiative defect trapping coefficients can be drastically reduced without forming the long‐lived, trapped charge species in ternary blends. The results highlight the novel protective mechanisms of engineering the alloy‐like composites for reinforcing the long‐term stability of NFA‐based ternary OSCs. Abstract : The stabilizing function of the alloy states is revealed based on simultaneous efficiency and storage stability boosting in PM6:BTP‐4Cl:PDI‐2T and PM6:DRCN5T:BTP‐4Cl ternary devices. The improved stability can be rationalized by two mechanisms: (1) the acceptor alloys enhance the conformational rigidity of BTP‐4Cl molecules. (2) The donor alloys optimize the fibril network of PM6 to restrict the aggregation of the BTP‐4Cl acceptor.