Two Y6 Derivations with Similar Chemical Structure As One Alloyed Acceptor Enable Efficient Ternary-Blend Polymer Solar Cells

A series of polymer solar cells (PSCs) was prepared with PM6 as the donor and Y6–1O and N3 as the acceptor based on a sandwich structure. The narrow bandgap material N3 was opted as the second acceptor to strengthen photon harvesting and morphology regulator to ameliorate the fill factor (FF) of ternary-blend PSCs. The two acceptors have similar highest unoccupied molecular orbits levels and chemical structures, which are conducive to forming an alloyed acceptor for sufficient charge transport in ternary hybrid films. By doping 10 wt % N3 in the acceptor, the FF and short circuit current density (JSC) of ternary-blend PSCs can be simultaneously improved, while keeping a constant open-circuit voltage (VOC) of 0.90 V. The power conversion efficiency (PCE) of ternary-blend PSCs is enhanced to 17.32%, which is much larger than the 16.14 and 15.93% for Y6–1O- and N3-based binary-blend PSCs. The more than 7% PCE improvement can be achieved via employing a ternary strategy with two Y6-series derivations as the alloyed acceptor. The alloyed acceptor should be a potential principle for picking materials to prepare high-performance ternary-blend PSCs.