Enhanced Performance of Dual Absorber Layer Based Quantum Dot Solar Cells over Single Absorber Layer Based Quantum Dot Solar Cells

Quantum dot solar cells (QDSCs) with single absorber layers have seen limited efficiency improvements over the years. To overcome this, introducing a dual absorber layer is a promising strategy for enhanced light absorption and overall performance. This study employs two efficient quantum dot materials, PbS‐QD and copper zinc tin sulfide QD (CZTS‐QD), in a dual‐layer configuration. While single‐layer QDSCs using PbS‐QD and CZTS‐QD achieved efficiencies of 26.8% and 24.5%, respectively, the PbS‐CZTS dual absorber layer QDSC achieved an improved efficiency of 27.85%. However, performance is slightly reduced to 26.99% due to parasitic resistances and temperature effects. To counter this, a reflective optical filter is integrated at the back contact, restoring and boosting the power conversion efficiency (PCE) to 28.18%. Further improvement is achieved through interfacial engineering between the absorber and hole transport layer, addressing nonradiative recombination caused by trap states. The incorporation of a BiI 3 interfacial layer with optimized thickness enhances interface quality, resulting in a final PCE of 28.40%. This work highlights the synergistic role of dual absorber layers, optical management, and interfacial engineering in pushing the efficiency limits of QDSCs.