Simulation of Lead-Free Double-Absorber Solar Cell Using Cs2TiBr6/La2NiMnO6 Over 33% Efficiency

Despite perovskite solar cells (PSCs) having seen significant improvements in efficiency, their path to industrialisation and commercialisation is hindered by considerable challenges. A major concern is the toxicity associated with lead-based perovskites, which also suffer from rapid degradation. To mitigate these issues, researchers are investigating lead-free alternatives. In this study, we developed a device structure for a lead-free PSC utilising Cs₂TiBr₆ and La₂NiMnO₆ as absorbers. By modifying the thickness of these layers with distinct bandgap values, we achieved current matching in the design, which was carried out utilising the solar cell capacitance simulator (SCAPS-1D) with the AM 1.5 G 1 sun light spectrum. The proposed optimised device structure includes layers of FTO, SnO₂, Cs₂TiBr₆, La₂NiMnO₆, GO and Au. SCAPS-1D is also utilised to assess the impact of defect density, different hole transport layers (HTLs) and operating temperature on the performance of the proposed double-absorber solar cell (DASC). Additionally, it is also examined how the back-reflective coating and varying solar spectra affect the proposed structure. At 300 K, the optimised design achieved a power conversion efficiency (PCE) of 33.38%, an open circuit voltage (V_oc) of 0.9158 V, a short-circuit current density (J_sc) of 43.47 mA/cm² and a fill factor (FF) of 83.85%.