Progressive performance enhancement of perovskite solar cells from single to triple absorber architectures: impact of defect density and thickness optimization

This paper presents a numerical investigation of perovskite solar cells (PSCs) using the Silvaco ATLAS simulator, focusing on a progressive transition from single to multi-absorber architectures. The reference architecture consists of ITO/ZnO/CsPbI3/Spiro-OMeTAD/Al. It is extended by introducing a CsxFA1−xPbI3 layer to form a double-absorber structure and subsequently incorporating FAPbI3 to obtain a triple-absorber structure. The simulation results indicate that photovoltaic performance improves as the number of absorber layers increases. The power conversion efficiency (PCE) increases from 18.19% for the single absorber device to 23.42% for the double absorber configuration, reaching 27.28% for the triple absorber structure. This improvement is mainly attributed to enhanced spectral utilization, improved light absorption, and increased photogeneration of charge carriers. In addition, the effects of defect density and absorber thickness are systematically investigated. The results indicate that CsₓFA₁₋ₓPbI3 is more sensitive to variations in defect density than CsPbI3 and FAPbI3. Thickness optimization further improves the predicted device performance, with FAPbI₃ identified as the most influential absorber layer. Under the investigated simulation conditions, the optimized triple absorber structure (CsPbI₃ (150 nm) / CsₓFA₁₋ₓPbI₃ (350 nm) / FAPbI₃ (700 nm)) reaches a simulated PCE of 28.44%, with a Jsc of 28.32 mA/cm², Voc of 1.197 V, and FF of 83.90%, highlighting the potential of multi-absorber bandgap engineering for designing high-performance perovskite photovoltaic architectures.