Exploring the Potential of Lead-Free Perovskite/ Kesterite Double Absorber Structure With Diverse Transport Layer Materials to Enhance Tandem Solar Cell Performance

Lead free perovskite materials with tandem structures hold the promise of enhanced stability, reduced environmental impact, and increased energy conversion efficiency, paving the way for a greener and more effective future in solar energy. Tandem solar cells play a crucial role in photovoltaic technology, going beyond the traditional limits of Shockley-Queisser constraints and capturing a broader range of the solar spectrum. This research delves into a unique tandem structure, incorporating a lead-free perovskite top cell (methylammonium germanium triiodide or MAGeI3) and a bottom cell composed of Kesterite material copper zinc tin selenide (CZTSe), utilizing SCAPS 1-D simulation. The study thoroughly examines the device’s performance, considering various electron and hole transport layers, their thicknesses, variations in absorber layers thicknesses, absorber layers defect density, and various back contacts to determine the optimal device configuration. Additionally, the impact of temperature, back reflecting coating, and different solar spectra on the proposed structure is analyzed. Among all simulated combinations, the FTO/SnO2/MAGeI3/ZnO: Al/CZTSe/Cu2O/Au configuration emerges as the most efficient, achieving an optimized efficiency of 33.86%. Quantum Efficiency (QE) and J-V characteristics showcase superior performance, featuring a short circuit current (J
$_{\mathrm {SC}}$
) of 17.16 mA/cm2, open circuit voltage (V
$_{\mathrm {OC}}$
) of 2.59 V, and fill factor (FF) of 76.51%. This study highlights the potential of perovskite/kesterite materials in achieving high-performance and environmentally friendly solar cells.