Multifunctional PMMA intermediate layer for sequentially deposited organic photovoltaics

Enhancing exciton generation, promoting exciton dissociation, and facilitating charge transport and collection within the photoactive layer is crucial for improving the performance of organic photovoltaics (OPVs). In this study, we achieved an optimal vertical distribution of the insulating polymer polymethyl methacrylate (PMMA) in the active layer through sequential deposition. This appropriate distribution of PMMA inhibited the aggregation of the acceptor, and reduced the donor-acceptor phase separation, increased exciton generation, promoted exciton dissociation, and inhibited bimolecular recombination. OPVs based on PM6/PMMA/L8-BO achieved a maximum efficiency of 18.1%, surpassing that of devices without PMMA. By tuning the vertical segregation of multi-components and molecular packing behaviors, this study provides an efficient method for achieving high performance by synergistically enhancing exciton generation, promoting exciton dissociation, inhibiting bimolecular recombination, and facilitating charge collection through PMMA.