Here, we report a promising perovskite solar cell structure based on a modified ZnO-nanorod interfacial structure with improved stability. An organic surface modifier, i.e., [6,6]-phenyl C-61 butyric acid methyl ester (PCMB), was employed between the perovskite and the ZnO-nanorod arrays to modify the interface condition. As a result, the optimized structure improves the light absorption, accelerates the transfer of the carriers, and reduces the electron and hole recombination losses in the solar cell. A perovskite solar cell with a structure of FTO/ZnO-nanorods/PCBM/CH3NH3PbI3 /Spiro-OMeTAD/Au gives an 18.8% enhancement in the short-circuit current density than a device without PCBM. Moreover, the open-circuit voltage was improved by 18.5% to 0.96 V. A power conversion efficiency of 11.67% was reached in cell with PCBM modification; results indicate that a modified ZnO-nanorod perovskite structure could have potential for even higher performance.