In this study, a lead-free nontoxic and hole transport material (HTM)-free perovskite solar cell (PSC) with a novel configuration of glass/FTO/ZnO/CH 3 NH 3 SnI 3Àx Br x /back contact has been modeled and optimized by a solar cell capacitance simulator (SCAPS). The bandgap of CH 3 NH 3 SnI 3Àx Br x absorber is tuned in the range of 1.3 eV to 2.15 eV by variation of the Br doping content. To make a comparison, an optimized Pbbased PSC is also modeled. By optimizing the parameters, power conversion efficiency (PCE) of 16.30%, open circuit voltage (V oc ) of 1.02 V, short circuit current density (J sc ) of 22.23 mA/cm 2 , and fill factor (FF) of 0.72 were obtained. As compare to the reports available in the literature, these results show much improvement and can provide guidelines for production of economic and environmentally friendly PSCs with further efficiency enhancement.*