Design and Numerical Simulation of Tandem Solar Cells Based on Sb2S3 to Improve Photovoltaic Performance

In this research, different tandem solar cells have been designed and simulated, in which the upper sub-cell is Sb2S3. Different structures including Sb2Se3, CISe, CZTSe and GeTe were proposed for the lower sub-cell.It is very important to match the current in the upper and lower sub-cells in consecutive cells. To reach the current matching point, the thickness of the layers of the lower sub-cell was kept constant and the thickness of the absorbing layer of the upper cell was changed so that the current density in both sub-cells was the same. At the current matching point, the performance of the upper cell under the AM1.5G standard spectrum radiation and the performance of the lower sub-cell under the filtered spectrum radiation were evaluated, and then the current-voltage characteristic curve of the tandem cell was obtained from the sum of the characteristic curves of the two sub-cells. The efficiency obtained for Sb2S3/Sb2Se3, Sb2S3/CIS, Sb2S3/CZTSe and Sb2S3/GeTe tandem cells was 22.10%, 30.95%, 24.83% and 36.80%, respectively. The greater the energy gap difference of the sub-cells, the more photons are collected and the greater current density is obtained for the cell. The best performance was obtained when GeTe was used as the bottom sub-cell.