A novel structure is proposed in this work for the efficiency enhancement of experimentally designed Sb2Se3 solar cell by device optimization, the band offset engineering, and Hole Transport Layer (HTL) with the aid of numerical modeling in SCAPS-1D simulator. J- V result of an experimental device was replicated in SCAPS-1D to validate simulated results. After validation of experimental solar cell result, device optimization of Sb2Se3/ZnO/FTO solar cell was performed and after device optimization, power conversion efficiency (PCE) of solar cell jumps from 3.59% to 11.29%. The PCE was further enhanced to value 14.46% by adjusting the band offset between Sb2Se3/ZnO interface. This task was accomplished by introducing Sn doped ZnO layer. Lastly, different HTL layers was applied to Sb2Se3/Zn(Sn, O)/FTO solar cell and among them CZTSe as HTL gave highest values of Fill Factor (FF), PCE, open circuit voltage (V-OC) and short circuit current (J(SC)), 81.18% and 18.50%, 0.66 V and 34.66 mA/cm(2).