Zinc Oxide (ZnO) with an easy synthesis method, low processing temperature, and high charge carrier mobility has been considered as a proper electron transport layer (ETL) for perovskite solar cells. Herein, we investigate the effect of the most common solvents for the preparation of ZnO and investigate their application as ETL for PSC. ZnO layers were prepared from three different solvents 2-methoxyethanol (2ME), isopropyl alcohol (IPA) and ethanol. A complete investigation of the structural, morphological, optical and device performance was performed. The results show that the type of solvent has a significant effect on electrical, optical and structural properties of ZnO layer, the capping perovskite layer composed of methyl ammonium lead iodide (MAPbI3) and the total performance of the cell. The ZnO film prepared by 2ME as the solvent showed the best performance mainly because of better surface coverage by MAPbI3, larger grain sizes, fewer pinholes, satisfying the Pb/I theoretical stoichiometry in the perovskite layer and the highest absorbance compared to other solvents. In addition, the simulation modeling shows that the ZnO (2ME)/MAPbI3 interface has the lowest defect density and for having planar ZnO-based PSCs with PCE of over 22%, the interface defects should be kept under 10(13) cm(-3).