High-efficiency top-emitting organic light-emitting diodes (OLEDs) with step-doped emission layers are numerically investigated. The simulation results demonstrate that the OLEDs with step-doped emission layers have better electrical performance and higher emitting intensity than those without step-doped design. Compared to conventional OLED devices, step-doped OLEDs with Fabry-Pérot microcavity not only have fixed wavelength but also have narrow emission spectral width. The simulation results suggest that the OLED structure with step-doped design in a Fabry-Pérot microcavity has superior performance and hence is beneficial for the display applications.