Morphology optimization and charge characteristics in PM6-based solar cells via ternary solvent processing

In this contribution, an optimized ternary solvent (chlorobenzene:chloroform:1,8-diiodooctane, CB:CF:DIO) was used to fabricate the high-efficiency polymer solar cells (PSCs). To analyze the effect of ternary solvent on the performance of PSCs, the relation among the morphology of active layer, charge generation-recombination and device performance of PM6:IT-4F solar cells was studied. The results showed that the morphology (i.e., aggregation state of donor and acceptor, phase separation degree) of active layer could be optimized at the ratio of 0.8:0.2 (CB:CF). Besides, we found that charge generation, charge transfer and charge mobility were improved in the CB:CF (0.8:0.2) processed PM6:IT-4F solar cells, thereby the charge recombination process in this device could be reduced compared with other CB:CF ratios processed devices. As a result, a power conversion efficiency of 12.85% was obtained in the CB:CF (0.8:0.2) processed PM6:IT-4F device.