Lattice Oxygen-Mediated Defect and Strain Regulation of SnO₂ via Water-Soluble Tb₂O₃ for High-Performance Perovskite...

Tin dioxide (SnO₂) is widely used as the electron transport layer (ETL) in n-i-p type perovskite solar cells (PSCs), yet its practical potential is plagued by intrinsic oxygen vacancies and structural defects arising from chemical bath deposition (CBD). Herein, we propose a facile pretreatment strategy: integrating water-soluble terbium oxide nanocrystalline (Tb₂O₃ NCs) into the CBD-derived SnO₂ ETLs post-cleaning but pre-annealing. Systematic characterizations confirm that Tb₂O₃ NCs induce a homogeneous SnO₂-Tb₂O₃ composite interface via lattice oxygen-mediated interfacial interaction. The abundant lattice oxygen of Tb₂O₃ NCs mediates the passivation of SnO₂ oxygen vacancies by replenishing oxygen defects. Meanwhile, the lattice oxygen-regulated composite ETL exhibits enhanced carrier mobility, reduced surface roughness, and optimized surface energy, which synergistically promote perovskite crystallization into large-grain films with superior light-trapping capability. Consequently, the target PSCs achieve a champion power conversion efficiency (PCE) of 25.95%. Furthermore, the lattice oxygen-mediated interfacial bonding mitigates ETL tensile strain under thermal cycling. These synergistic merits significantly enhance the device's humidity stability and operational stability in ambient air. This work provides a facile and scalable strategy to simultaneously engineer the defect state and structural integrity of SnO₂ ETLs, offering valuable insights for the rational design of high-efficiency and stable PSCs.