The proposed lead-free Cs3Sb2Br9 (Cesium Antimony Bromide) perovskite is newly discovered material with numerous beneficial optoelectronics properties and nontoxic. While this proposed perovskite used in optoelectronics applications before. For the first time, we proposed Cs3Sb2Br9 as an absorber within a solar cell device. With its optimized parameters, our proposed perovskite solar cell (PSC) achieved an impressive power conversion efficiency (PCE) of 12.88% having open-circuit voltage (VOC) of 2.07 V, short-circuit current density (JSC) of 7.01 mA/cm2, and fill factor (FF) of 88.63% which is considerable performance of Cs3Sb2Br9 PSC in comparison to other reported Cs based PSCs in the study.