Numerical study on the effect of ZrS₂ on CZTSSe based thin-film solar cells using SCAPS 1-D

Third-generation thin-film solar cells based on CZTSSe are highly attractive because of their exceptional optoelectrical properties, low fabrication costs, earth-abundant, and less toxic constituting elements. Herein we propose a CZTSSe based solar cell and aim to report for the first time, the effect of using a nontoxic n-type ZrS₂ transition metal dichalcogenides (TMDCs) as a buffer layer. The simulated structure is Al-doped ZnO(AZO)/ZrS₂/CZTSSe/Mo and the performance of the proposed solar cell was analysed using the Solar Cell Capacitance Simulator (SCAPS-1D) program. To investigate the impact of the ZrS₂ layer on the performance of the proposed device, its donor density and electron affinity was varied from 1E12 cm^-3 to 1E16 cm^-3 and 4.4 eV to 4.8 eV respectively. The simulation results indicate that the donor density doesn't play a huge role in the photovoltaic parameters of the device within the tested range, while the efficiency of the device increased from 20% to 23% with an increase in the electron affinity of the ZrS₂ layer. Besides the influence of the buffer layer, a study was also carried out to find the role of operating temperature and the intrinsic layer on the proposed device. The temperature was varied from 300 K to 500 K and the thickness of the ZnO layer from 0.03 μm to 0.07 μm. Most of the parameters declined rapidly with the increase in temperature while it remain constant with the change in ZnO thickness. Efficiency dropped to 9% at 500K from 23 % at 300K and the efficiency of the device remained 23% with the variation of intrinsic layer thickness. The results as a whole suggest that the ZrS₂ could be a practical alternative for fabricating nontoxic CZTSSe solar cells. (author)