Enhancing the electron blocking ability of n-type MoO₃ by doping with p-type NiO_x for efficient nonfullerene polymer solar cells

MoO₃ is a promising n-type anode interfacial layer (AIL) with high work function for polymer solar cells (PSCs). However, due to the limited electron blocking ability of n-type metal oxide, the interfacial recombination occurs inevitably in the MoO₃/organic interface. Herein, we for the first time strategically introduced minimal amount of p-type NiO_x into n-type MoO₃ to enhance the electron blocking ability of AIL. The MoO₃ doped with NiO_x layer (MoO₃:NiO_x) is highly transparent with a conduction band of 3.25 eV and a work function of 5.10 eV, which prolongs the electron lifetime of PBDB-T:IT-M based device from 0.63 to 5.05 μs. Benefiting from the prolonged lifetime and enhanced charge collection of MoO₃:NiO_x AIL, the average power conversion efficiency (PCE) of PBDB-T:IT-M based devices is significantly improved to 10.81%, much higher than that of control devices with PEDOT:PSS (9.79%), MoO₃ (8.97%) and NiO_x (9.51%) AILs. Our findings provide a new approach to tuning the energy level of cost-efficient and simply processed metal oxide interfacial materials for high performance and stable nonfullerene PSCs.