Design and Optimization of CH₃NH₃SnBr₃/CuInSe₂ Monolithic Tandem Solar Cell with Enhanced Efficiency using SCAPS-1D

In the recent years, there have been tremendous breakthroughs in renewable energy due to the growing emphasis on decreasing human environmental effect. Many reasons, including an ever-increasing human population, better living standards, increased urbanization and increased international trade, have contributed to the dramatic increase in energy use in recent decades. As an excellent alternative to the fossil fuels,solar cells are seen as a modern power generation source. The low price and great performance of third-generation solar cells are making them increasingly popular. This is especially true with cells made of perovskites. Solar cells with a tandem structure are more efficient than those with a single junction because they can absorb more of the sun’s radiation. By incorporating CuInSe<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> as the bottom cell and Methylammonium Tin Bromide ($\mathbf{M A S n B r}_{3}$) as the top cell, this study brings new concepts to the table. An impressive efficiency of 41.68% is achieved by the tandem structure with MASnBr<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> as top cell and CuInSe ${ }_{2}$ as bottom cell, featuring $V_{\text {oc }}$ of 1.71 volts, $\mathrm{J}_{\text {sc }}$ of $30.55 \mathrm{~mA} / \mathrm{cm}^{2}$, and FF of 80.07%. The improved efficiency is attributed to the low bandgap of the bottom cell and the high bandgap of the top cell material.