Numerical analysis on ZnxCd1−xS/CdTe solar cells with different buffer layers, front and back contacts

In this work, a numerical analysis on cadmium stannate (Cd₂SnO₄) as front contact, zinc stannate (Zn₂SnO₄) as buffer layer and antimony telluride (Sb₂Te₃) with molybdenum (Mo) as back contact has been conducted in the conventional (SnO₂/CdS/CdTe/Ag) CdTe cell structures. Here, CdS window layer is replaced by zinc cadmium sulphide (Zn_xCd_1-xS) aiming to improve efficiency and stability utilizing Analysis of Microelectronic and Photonic Structures (AMPS 1D) simulator. Efficiency as high as 17.0% has been found with 80 nm of Zn_xCd_1-xS window layer for x=0.1, 1 μm of CdTe layer and 100 nm Zn₂SnO₄ buffer layer without Sb2Te₃ back contact. However, ZnO insertion shows lower conversion efficiencies of 11.84% and 14.26%, respectively with and without Sb₂Te₃ back contact. It has been found that 1 μm of CdTe absorber layer, 70 nm of Zn_xCd_1-xS (x=0.1) window layer, 100 nm of Zn₂SnO₄ buffer layer and 100 nm Sb₂Te₃ back contact layer are sufficient for high efficiency (>;18.5%) Zn_xCd_1-xS/CdTe cells. Moreover, it has been found that the cell normalized efficiency linearly decreases with the increasing operating temperature at the temperature gradient of -0.3%/°C proving its stability as others.