Non-Fullerene Acceptors with Benzodithiophene-Based Fused Planar Ring Cores for Organic Solar Cells

Fused aromatic rings are widely employed in organic solar cell (OSC) materials due to their planarity and rigidity. Here, we designed and synthesized four two-dimensional non-fullerene acceptors, D6-4F, D6-4Cl, DTT-4F, and DTT-4Cl, based on two new fused planar ring structures of f-DTBDT-C6 and f-DTTBDT. Owing to the desirable phase separation formed in the blend films and the higher energy levels induced by the extra alkyl groups, PM6:D6-4F-based devices achieved a high VOC = 0.91 V with PCE = 11.10%, FF = 68.54%, and JSC = 17.75 mA/cm2. Because of the longer pi-conjugation of the f-DTTBDT core with nine fused rings, DTT-4F and DTT-4Cl showed high molar extinction coefficients and broad absorption bands that enhanced the current density of OSCs. Finally, the PM6:DTT-4F-based devices achieved a JSC = 19.82 mA/cm2 with PCE = 9.68%, VOC = 0.83 V, and FF = 58.85%.

Automated summary

In this study, four two-dimensional non-fullerene acceptors were designed and synthesized based on two new fused planar ring structures of f-DTBDT-C6 and f-DTTBDT. Devices based on PM6:D6-4F achieved high VOC = 0.91 V, PCE = 11.10%, FF = 68.54%, and JSC = 17.75 mA/cm2, due to the desirable phase separation in the blend films and higher energy levels induced by the extra alkyl groups. DTT-4F and DTT-4Cl, with longer pi-conjugation of the f-DTTBDT core, exhibited high molar extinction coefficients and broad absorption bands, enhancing the current density of organic solar cells. Finally, PM6:DTT-4F-based devices achieved a JSC = 19.82 mA/cm2 with PCE = 9.68%, VOC = 0.83 V, and FF = 58.85%.