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Altering alkyl-chains branching positions for boosting the performance of small-molecule acceptors for highly efficient nonfullerene organic solar cells
摘要： The emergence of the latest generation of small-molecule acceptor (SMA) materials, with Y6 as a typical example, accounts for the surge in device performance for organic solar cells (OSCs). This study proposes two new acceptors named Y6-C2 and Y6-C3, from judicious alteration of alkyl-chains branching positions away from the Y6 backbone. Compared to the Y6, the Y6-C2 exhibits similar optical and electrochemical properties, but better molecular packing and enhanced crystallinity. In contrast, the Y6-C3 shows a significant blue-shift absorption in the solid state relative to the Y6 and Y6-C2. The as-cast PM6:Y6-C2-based OSC yields a higher power conversion efficiency (PCE) of 15.89% than those based on the Y6 (15.24%) and Y6-C3 (13.76%), representing the highest known value for as-cast nonfullerene OSCs. Prominently, the Y6-C2 displays a good compatibility with the PC71BM. Therefore, a ternary OSC device based on PM6:Y6-C2:PC71BM (1.0:1.0:0.2) was produced, and it exhibits an outstanding PCE of 17.06% and an impressive fill factor (FF) of 0.772. Our results improve understanding of the structure-property relationship for state-of-the-art SMAs and demonstrate that modulating the structure of SMAs via fine-tuning of alkyl-chains branching positions is an effective method to enhance their performance.
关键词： power conversion efficiency,fill factor,small molecular acceptor,alkyl-chain branching position,organic solar cell
更新于2025-09-23 15:19:57
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Impact of alkyl chain branching positions on molecular packing and electron transport of dimeric perylenediimide derivatives
摘要： Side chains play a critical role in tuning intermolecular interaction and charge transport in organic semiconductors. Here, we have systematically investigated the impact of branching positions of the alkyl side chains on the molecular packing and electron transport properties of a series of bay-linked dimeric perylenediimide (PDI) derivatives by atomistic molecular dynamics simulations in combination with charge transfer rate theory and kinetic Monte Carlo simulations. The results show that despite of different branching positions of the alkyl chains, π –π stacking is effectively inhibited for all the dimeric PDI derivatives. As the branching position moves away from the PDI backbone, the appearance of the alkyl atoms around the PDI backbone will first decrease and then increase. Correspondingly, the short contacts between the PDI moieties are first enhanced and then reduced. In particular, when the branching position is at the third carbon atom, the intermolecular connectivity becomes the most effective and the electron mobility is significantly increased by 2 times.
关键词： Electron mobility,Branching position,Perylenediimide,Molecular packing
更新于2025-09-10 09:29:36