Multicomponent Solvent Engineered Spatially Uniform 2D/3D Perovskite Heterojunction for Solar Cells

This study introduces a multicomponent solvent engineering approach for constructing high-quality 2D/3D metal halide perovskite (MHP) heterostructures, addressing vertical inhomogeneity in ultrathin 2D capping layers for perovskite solar cells (PSCs). Through synergistic solvent coordination, isopropyl alcohol spatially confines 2D layer formation at the 3D perovskite surface, while dimethyl sulfoxide induces controlled 3D matrix dissolution to enable vertical phase propagation. Acetonitrile optimizes solvent penetration dynamics, achieving 2D layers with exceptional spatial homogeneity across multiple cation systems. The optimized PDAI₂-derived 2D/3D architecture demonstrates a certified power conversion efficiency (PCE) of 25.57% (champion 26.14%) with an 85.62% fill factor, attributed to enhanced interfacial charge transport at the C₆₀/perovskite junction through reduced nonradiative recombination. The spatially uniform 2D capping layer confers remarkable operational stability, retaining 92% initial PCE after 5,000 h dark aging and 90% efficiency following 1,700 h maximum power point tracking under continuous 1-sun illumination.