Back contact plays a vital role in the device performance of PSC. The efficiency of the cell increase with the increment of the metal work function of back contact. In this section, two cells are simulated by ten different back contact materials. The metal work function of different back contact materials is given in Table . By investigating Figure , it can be said that the efficiency is increasing with the metal work function (eV) of back contact, and after a particular value of the metal work function (eV), the efficiency is almost constant. Here, six back contacts can retain maximum efficiency for both optimized cells. As we aim to determine a low-cost and highly efficient cell structure, we will choose the back contact material according to the price of the materials from these six back contact materials. The price of each material is taken from Sigma Aldrich