Optimizing energy levels in perovskite solar cells with dual-hole and dual-electron transport layers

To address the interface carrier recombination and band mismatch associated with the single transport layer design in conventional perovskite solar cells, a dual-electron transport layer (ETL: ZnO/CDS) and a dual-hole transport layer (HTL: Se-Te: Cu₂O/NiO) were proposed. Numerical simulations based on Poisson and carrier continuity equations were employed to systematically investigate the conduction band offset (CBO), valence band offset (VBO), and carrier dynamics. The achievement of optimized energy band alignment and charge transport pathways led to remarkable performance enhancements: the fill factor (FF) increased to 84.04%, short-circuit current density (J_sc) reached 21.39 mA cm^-2, and a certified efficiency (E_ta) of 20.14% was obtained. Thus, the proposed dual transport layer strategy offered effectiveness in overcoming efficiency limitations while providing theoretical guidance and design principles for developing high-stability tandem solar cells through advanced energy band engineering.