16.55% efficiency ternary organic solar cells enabled by incorporating a small molecular donor

Abstract

The introduction of a third component into the binary system to construct a ternary architecture is widely applied to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, a small molecule donor, SM1, was introduced into the PM6:Y6 binary system where a high PCE of up to 16.55% was achieved after the addition of 15 wt% of SM1 in the donors with an open-circuit voltage (V_oc) of 0.831 V, a short-circuit current density (J_sc) of 25.7 mA cm⁻², and a fill factor (FF) of 77.5%, which was much higher than that of the PM6:Y6 binary systems (15.75%), presenting a V_oc of 0.845 V, a J_sc of 25.3 mA cm⁻², and a FF of 73.7%. The introduction of SM1 improved the charge extraction, exciton dissociation, and blend of the morphology while effectively reducing bimolecular recombination. As a result, the J_sc and FF of the ternary devices greatly improved. This study presents an effective method to improve the PCE by adopting a ternary strategy, while at the same time, promoting a simple fabrication technology.