First of all, the front contact metal work function has been set as 4eV and found that the PCE is dropped to The cell is simulated with the parameters given in Table and the output parameters illustrated in Fig. are achieved. Price of each materials are taken from Sigma Aldrich However, there are four back contact materials which can provide optimal efficiency, that's why we have considered the price of each material and analyzed further to find the best back contact material. It is obvious according to table 4 that, the best back contact material for our proposed cell is Ni which is the cheapest material but can provide optimal efficiency.