Retarding the Growth Kinetics of Chemical Bath Deposited Nickel Oxide Films for Efficient Inverted Perovskite Solar...

The interfacial contact between the hole transport layer (HTL) and perovskite layer plays a critical role in determining the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Herein, to address the limitations of commercial NiO_x nanoparticles and realize low temperature fabrication of compact NiO_x film, a chemical bath deposition (CBD) approach is employed and strategically modified. By introducing an amino-alcohol ligand of triisopropanolamine (TPA) into the precursor, the deposition process is effectively controlled. TPA binds strongly with Ni²⁺ ions, facilitating their gradual release and promoting the in situ formation of a compact Ni(OH)₂ intermediate. This retarded growth kinetics yield high-quality NiO_x films with enhanced coverage, increased conductivity, and reduced trap-state. The films also feature abundant hydroxyl groups, providing sufficient anchoring sites for MeO-2PACz. Based on this bilayer HTL, a PCE of 26.53% (certified 26.44%) with improved operational stability is achieved for the 0.09 cm² device, marking the highest efficiency for inverted PSCs based on CBD NiO_x. Furthermore, the strategy demonstrates excellent scalability, delivering efficiencies of 24.75% for a 1 cm² device and 22.96% for a 12.96 cm² minimodule. This work provides a facile but effective CBD approach for preparing high-quality NiO_x films, offering a promising and scalable pathway for inverted PSCs.