Appreciable progress of organometal halide perovskite materials has been achieved in recent years due to their controllable synthesis and excellent optoelectronic properties. And the potential uses of these perovskites in photovoltaics, light-emitting diodes (LEDs), photodetectors and lasers have been successfully demonstrated. Although organometal halide perovskites appear as emitters with extremely high color purity and low cost, the device performance is significantly limited by poor morphology of the perovskite layer. The addition of the polymer into the perovskite layer is a convenient and effective method to improve the homogeneity of the spin-coated perovskite film. In this work, we fabricate green perovskite light emitting diodes (PeLEDs) with poly(styrenesulfonate) (PSS)-modified poly(3,4-ethylenedioxythiophene):PSS (PEDOT:PSS) as the hole injection layer (HIL) and a single spin coating composite film consisting of methylammonium lead tribromide (MAPbBr₃) and poly(ethylene oxide) (PEO) as the emissive layer. The PSS doping increases the work function of PEDOT:PSS and reduces the injection barrier between PEDOT:PSS HIL and MAPbBr₃ perovskite, thus balancing the carriers within the PeLEDs. The PEO doping enables the MAPbBr₃ to become a dense and uniform perovskite film with a ~100% coverage. With the above approaches, highly efficient PeLEDs with maximum luminance and current efficiency of 2476 cd·m^–2 and 7.6 cd·A^–1 are eventually acquired. This work provides a method of fabricating the high-coverage and high-efficiency PeLEDs.