The present work reports a comparative study between single and mixed organic cation based MAPbI3 and MA0.6FA0.4PbI3 perovskite devices fabricated in conjunction with low temperature processed (<150 °C) ZnO electron transport layers. MA0.6FA0.4PbI3 perovskite devices demonstrate 37% higher power conversion efficiency compared to MAPbI3 perovskite devices developed on the ZnO ETL. In addition, MA0.6FA0.4PbI3 devices exhibit very low photocurrent hysteresis and they are three-fold more stable than conventional MAPbI3 PSCs (perovskite solar cells). An in-depth analysis on the charge transport properties in both fresh and aged devices has been carried out using electrochemical impedance spectroscopy analysis to comprehend the enhanced device stability of the mixed perovskite devices developed on the ZnO ETL. The study also investigates into the interfacial charge transfer characteristics associated with the ZnO/mixed organic cation perovskite interface and concomitant influence on the inherent electronic properties.