Modification of hole transporting layers has proved an effective approach to improve the photoelectric conversion efficiency of perovskite solar cells. In this work, we report a highly dispersed graphene composite prepared by skillfully using the synergistic pi-pi interaction between graphene sheets and functional carbon nanotubes (f-CNTs). The graphene:f-CNTs HTLs demonstrate excellent conductivity and hole mobility. The hydrophobic graphene:f-CNTs HTL can also act as a scaffold for crystallization of perovskite layer and improve the device stability due to the beneficial interface. As a result, an improved PCE of 14.8% has been achieved with significant reproducibility. In addition, the optimized device with graphene:f-CNTs HTLs shows excellent stability and performance without encapsulation due to its neutral property. This approach can provide a good way for the future structure of perovskite solar cells.