Environmental Control of Tin Perovskite Crystallization via Solvent Vapor Fuming

High Resolution Image Download MS PowerPoint Slide We systematically explored solvent vapor treatment (SVT) using 12 different solvents to optimize lead-free tin perovskite solar cells (TPSCs) prepared via a two-step fabrication. Guided by density functional theory (DFT) and macroscopic parameter screening, 1,1,3,3-tetramethylurea (TMU) was identified as the superior fuming agent due to its high donor number, moderate dielectric constant (ε = 24.5), and optimal vapor pressure (∼1.6 Torr). These properties facilitate a controlled dissolution-recrystallization process, resulting in dense, strain-relaxed films with large grains, a low surface roughness with RMS 17.0 nm, and uniform surface potential. Advanced optoelectronic characterizations, including QFLS mapping and transient photovoltage/photocurrent (TPV/TPC) measurements, confirm that TMU treatment resolves the fundamental carrier dynamic trade-off—simultaneously enabling swift charge extraction (0.67 μs) and profoundly suppressing interfacial non-radiative recombination (75.14 μs). Consequently, the optimized TPSC achieved a record power conversion efficiency (PCE) of 10.45% alongside a maximized thermodynamic potential (QFLS peaking at 1.028 eV). Furthermore, the devices demonstrate exceptional long-term durability, exceeding 6000 hours of operational stability. This study highlights the critical role of multidimensional solvent engineering—bridging molecular interactions with macroscopic crystallization—to realize highly efficient and stable tin perovskite photovoltaics.