The efficiency of CdTe based solar cell can be increased using ternary CdZnTe material as absorber layer. Cd1-xZnxTe has tunable bandgap depending on the composition. In this work the bandgap of CdZnTe layer (1.57 eV) which is in the optimum range, can be achieved with Zn composition of x=0.1. First the carrier concentration of absorber layer in the baseline case is increased then the thicknesses of absorber layer and window layer in the conventional baseline case are reduced and optimized. Finally an optimized cell structure is proposed. After optimization, the total thickness of the baseline case cell is reduced by factor four and results high efficiency. The cell structure in both baseline case and modified cell is: (SnO2/CdS/CdZnTe/Back Contact), however some material parameters are different. The performance parameters are found better in the optimized cell structure. We also investigated the effect of ZnO buffer layer and the operating temperature on the performance parameters.