High efficiency ternary organic solar cells enabled by compatible dual-donor strategy with planar conjugated structures

Ternary organic solar cells (OSCs) have received extensive attention for improving the power conversion efficiency (PCE) of organic photovoltaics (OPVs). In this work, a novel donor material (ECTBD) consisting of benzodithiophene (BDT) central electron donor unit was developed and synthesized. The small molecular donor has the same central unit as PM6. The addition of ECTBD into PM6:Y6 system could improve the morphology of active blend layer. In addition, ECTBD showed good morphologically compatibility when blending with PM6:Y6 host, resulting in the improvement of fill factor and current density. As a result, the ternary devices based on PM6:ECTBD:Y6 ternary system achieved a highest PCE of 16.51% with fill factor of 76.24%, which was much higher than that of the binary devices (15.7%). Overall, this work provided an effective strategy to fabricate highly efficient ternary organic solar cells through design of the novel small molecular donor as the third component.