In this paper the effect of Cl doping on optical, photovoltaic and morphological properties of mixed halide perovskite (CH3NH3PbI3-xClx) structure in a solar cell has been reported. The perovskite layer was spin-coated by employing sequential deposition method over a PEDOT-PSS hole transport layer. Lastly, the device was finished by coating Al via thermal evaporation. The addition of 10% methylammonium chloride (MACl) by weight into the methylammonium iodide (MAI) solution as additive was improved the photovoltaic performance of the solar cell, since the Cl doping has positive effect on the growth of perovskite crystals in the final film. Furthermore, addition of MACl enables the formation of smoother films and thus reduces photocurrent leakage due to pinholes or incomplete surface coverage. The Cl doping also increases reproducibility of planar devices for consistent device results.