Impact of Linker Engineering in Core-Linked Dimeric Acceptors for High-Performance Organic Solar Cells

Abstract

The dimerization of small molecule acceptors (SMAs) is a promising strategy for enhancing the long-term stability and power conversion efficiency (PCE) of organic solar cells (OSCs). However, the reported DSMAs are primarily limited to end-linked molecular configurations, highlighting the need for further exploration of various dimer architectures. Herein, the development of two distinct core-linked dimerized SMAs (DYF-V and DYF-E) are reported with tailored linker structures (vinylene and ethynyl, respectively), achieving high-performance OSCs (PCE = 18.53%). Interestingly, a subtle change in the linker structures results in markedly different molecular properties and photovoltaic performances of the dimer acceptors. DYF-E with an ethynyl linker exhibits more twisted backbone conformation and mitigated aggregation property compared to DYF-V, inducing desirable blend morphologies with a polymer donor including high crystallinity, face-on oriented packing structures, and well-intermixed domains. Thus, the DYF-E-based OSCs exhibit a high PCE (17.02%), which significantly outperforms the DYF-V-based OSCs (PCE = 9.98%). Furthermore, the ternary OSCs based on DYF-E achieve a higher PCE of 18.53%. Thus, this study highlights the significance of selecting an appropriate linker in core-linked dimerized SMAs for producing high-performance OSCs.,The development of two distinct core-linked dimerized small molecule acceptors (DYF-V and DYF-E) is reported with different linkers of vinylene and ethynyl. This small change in the linker structures affects the aggregated/crystalline behaviors of the dimers, which greatly impact the blend morphology with a polymer donor and the performance in organic solar cells. image,