In this study, we successfully doped Germanium sulfide (GeS) particles in methylammonium lead triiodide (CH3NH3PbI3) films to create highly efficient inverted perovskite solar cells (PSC). Various characterization methodologies were employed to examine the impact of GeS on the morphological, structural, and compositional properties of the CH3NH3PbI3 perovskite. The X-ray diffraction and Raman spectroscopy analyses of the synthesized products demonstrated that the crystallinity was enhanced, and tetragonal perovskite structures were generated without any impurities when GeS was used at a high concentration. The surface morphology results indicated that the CH3NH3PbI3 perovskite possessed thin coatings with compact, uniform, and smooth surfaces, with large grain size. The production of a high-quality CH3NH3PbI3 film from the CH3NH3PbI3: GeS phase results in improved carrier lifetime, decreased charge-trap density, and nonradiative recombination of the perovskite films. Band gap was observed to be correlated with grain size and crystallinity, which was accompanied by an increase in GeS concentration. We attained a maximum conversion efficiency of 17.46 % by fabricating solar cells with the following structure: soda-lime glass FTO/TiO2/CH3NH3PbI3: GeS/spiro-oMeTAD/Au. Based on our findings, we believe that the doping of GeS is a promising method for improving the properties of perovskite solar cells that are based on CH3NH3PbI3 thin films.