Study on the Numerical Modeling of CdTe/CdS/SnO₂ Based Thin Film Solar Cells Using SCAPS–1D

In response to changes in material or design, a suitable simulator can be used to predict the novel solar cell’s performance. Employing one dimensional Solar Cell Capacitance Simulator (SCAPS-1D) software, this work analyses cadmium telluride (CdTe) solar cell’s fundamental parameters & performance. The solar cell used for this work is comprised of CdTe(p)-CdS(n)-SnO2(n+); where CdTe, SnO2, and CdS act as absorber layer, window layer and buffer layer respectively. The work primarily focuses on 1) layer thickness optimization for various layers, 2) the impact of the CdS layer's electron affinity, and 3) the impact of a highly doped (p+) thin layer of CdTe acting as the PV device's back surface field [1]. The band gap and thickness of the layers are kept constant during simulation at their ideal or predetermined levels. The employed CdTe(p), CdS(n) and SnO2(n+) band gaps are 1.5eV, 2.4eV, and 3.6eV, respectively, with corresponding thicknesses of 2.0 µm, 25 nm, and 0.5 µm. The solar cell's efficiency dropped from 19.24% to 18.63% as the electron affinity of the CdS layer rose from 3.75eV to 4.2 eV. The addition of a 0.1 µm thick p+ rear surface layer increased the efficiency of the solar cell to 21.96%. The optimized absorber, buffer and window layer thicknesses are 4 µm, 15 nm and 0.2µm correspondingly. At an electron affinity of 3.75 eV for the CdS layer, the highest output cell efficiency metrics obtained are JSC=25.141mA/cm2, VOC=1.0538V, FF%=88.16 % and η%=23.36%.