Yi Hou

Formamidinium-rich perovskite solar cells (PSCs) have achieved remarkable efficiencies, yet their phase purity is often compromised by the competitive nucleation of the nonperovskite δ-phase during rapid processing. Herein, we demonstrate an electrohydrodynamic (EHD)-mediated chemical strategy to bypass this kinetic trap using a multifunctional molecular, tetramethylthiourea (TeMTU). By precision tuning of the surface tension-Coulombic repulsion balance, TeMTU orchestrates the EHD-driven microdroplet evolution, effectively locking the in-flight precursor into a critically supersaturated state that fundamentally suppresses δ-phase nucleation. Beyond macroscopic fluid dynamics, molecular-level investigations reveal that TeMTU forms robust coordination complexes with the lead halide framework. This chemical intervention significantly elevates the activation energy barrier for the α-to-δ phase transition by 42%, as corroborated by Density Functional Theory and variable-cell double-ended surface walking analysis. The resulting α-phase FA-based films exhibit exceptional crystallinity and a minimized defect density, enabling electrospray-fabricated PSCs to achieve an impressive power conversion efficiency (PCE) of 26.24% (0.05 cm2) and 25.39% (1.0 cm2). Furthermore, the chemically stabilized lattice demonstrates operational durability, retaining 95% of its initial PCE after 3000 h of continuous maximum power point tracking at 65 °C.

Low-dimensional perovskite engineering offers a promising route to improve both power conversion efficiency and stability in perovskite photovoltaics, yet the mechanistic relationship between organic ligand design and structural control remains elusive. Here, we report a molecular design strategy for bis-imidazolium ligands that enables precise dimensional tuning of perovskite architectures, from zero-dimensional through parallel one-dimensional to bridged zero-dimensional configurations. Through systematic variation of terminal groups and inter-imidazole spacing, we achieve controlled growth of high-quality hybrid dimensional perovskite films with optimized crystallization kinetics and charge transport properties. This enables photovoltaic devices with a certified power conversion efficiency of 27.02% (laboratory 27.21%). Scaling this dimensional strategy enables the fabrication of 30×30 cm² perovskite solar modules, achieving a champion power conversion efficiency of 21.41% Moreover, unencapsulated devices retain 94.3% of their initial power conversion efficiency after 2000 hours of continuous operation at 60 °C (ISOS-L-2I), highlighting exceptional operational stability.

Based on co-evaporated wide-bandgap perovskites, ∼1% PbCl ₂ vapor additive is added to suppress phase segregation and ionic losses, leading to record-stable perovskite–organic tandem cell compared to other kinds of perovskite-based thin-film tandems.