Collaborative Optimization of Charge Carrier Dynamics and Energy Loss of Organic Solar Cells via Rational Morphology Regulation

ABSTRACT Generally, the required dominant J ‐aggregation and ordered molecular stacking via morphology optimization gives rise to red‐shifted absorption spectrum with lower optical energy bandgap ( E g ), resulting in the adverse effect on the open‐circuit voltage ( V oc ) improvement in organic solar cells (OSCs). To maximize power‐conversion efficiency (PCE), it is desirable to reduce the energy loss ( E loss ) of OSCs to refrain from decreasing the V oc via rational morphology optimization. Herein, we reveal the effect of solid additive treatment on collaboratively optimizing the charge carrier dynamics and E loss to maximize short‐circuit current density and fill factor without decreasing the V oc of OSCs. In addition to improving the J ‐aggregation and molecular stacking of D18:N3 blend for efficient charge separation and transport, it is found that the biphenyl (BPh) additive treatment significantly reduces the E loss to offset the lower E g for maintaining the high V oc of OSCs. As a result, the BPh additive treatment shows remarkable effect in boosting the PCE of OSCs. In particular, the BPh additive treatment for the D18:N3:L8‐BO‐4Cl‐based device significantly elevates the PCE from 18.95% to 20.10%.