Modelling and Optimization of Tin Based Perovskite-Perovskite Tandem Solar Cell With Scaps-1d Software

Abstract

With the rapid depletion of the organic fuel reservoirs and the increasing demand of renewable energy sources, significant research efforts have been focused on developing photovoltaic devices which are capable of having a superior efficiency compared to the previous generations. Third generation solar cells, comprised of but not limited to technological advancements such as tandem solar cells and perovskite solar cells, have demonstrated potential in this domain. However, the presence of lead and other toxic materials in the construction of such devices has prompted a search for an alternative to these toxic materials in order to facilitate production of clean energy and to reduce the concerns regarding the disposal of solar cells. In recent developments, the use of tin-based perovskites have garnered a interest as an alternative to lead-based perovskites in the solar cell sector since they lack the toxicity and instability issues that are inherent to lead-based perovskites. In this work, a simulation study have been conducted on a tandem solar cell composed of two tin-based perovskite materials in the top and bottom absorber layers. The cesium tin iodide (Cs2SnI6) cell with 1.48 eV bandgap has been used as the top cell while the methylammonium tin iodide (CH3NH3SnI3) cell with 1.23 eV bandgap has been used as the bottom cell. The combination of these two individual cells in a tandem cell initially resulted in a power conversion efficiency (PCE) of 22.67%. Parametric analysis has been performed with the view to determine the optimal choices for absorber layer thickness, ETL and HTL material selection and thickness, defect density state in the absorber layer and interfaces, and the back contact metal used in the construction of the solar cell. As a result of the enhancement of the two cells, the open circuit voltage (Voc) was found to be 0.798 V, the short circuit current density measured at 37.54 mA/cm2 , with the fill factor (FF) being 76.61%. After performing the mentioned optimizations of the solar device, a reasonable power conversion efficiency (PCE) of 22.96% was achieved. All the simulations of this work were conducted using SCAPS-1D software utilizing AM 1.5G illumination.