Multiple chlorinations to improve the performance of unfused electron-acceptor based organic photovoltaic cells

Organic solar cells (OSCs) with non-fused ring acceptors have improved steadily in recent years, benefiting from the subtly molecular regulation and well-organized blend film morphology. Herein, a simple and effective strategy was proposed for finely chemical structural regulation from a well-established molecule BDTC-4Cl. With this, two unfused acceptors namely Cl-4F and Cl-4Cl were designed and synthesized. After adding a chlorine atom into the core unit and a fluorine atom into the end group, the molecule Cl-4F achieved high efficiency of 10.38% and short-circuit current density (JSC) of 19.59 mA cm(-2), which is superior to that of the control molecule BDTC-4Cl (9.42%) without chlorine atom in the central backbone. When using multi-chlorination in the end group and backbone, the Cl-4Cl based device obtained an exciting efficiency of 10.88%, a fill factor (FF) of 65.2%, and a JSC of 20.07 mA cm(-2). The Cl-4Cl-based device's power conversion efficiency (PCE) ranks among the highest values for non-fused ring acceptors with a benzodithiophene (BDT) core, demonstrating the feasibility of using multiple chlorination strategies to design and construct novel non-fused ring acceptors for high-performance OSCs.

Automated summary

Non-fused ring acceptors in organic solar cells have shown improved performance in recent years due to precise molecular regulation and well-organized blend film morphology. In this study, a simple and effective strategy was proposed to finely tune the chemical structure of the acceptors. Through the addition of chlorine and fluorine atoms, high efficiencies and current densities were achieved in the resulting devices. This research demonstrates the feasibility of using multiple chlorination strategies to design novel acceptors for high-performance organic solar cells.