High-rate fabrication of efficient perovskite solar cells via vapor transport deposition and PbI2 microstructure engineering

In the perovskite solar cell (PSC) industry, vacuum-based fabrication of PbI 2 and perovskite layers has seen limited utilization due to the inherently slow deposition rates of conventional thermal evaporation or sputtering processes (<1 nm/s). In this work, PbI 2 films were deposited by a vacuum technology known as vapor transport deposition (VTD) at a peak rate of 10 nm/s, and subsequently converted to perovskite through a high-throughput spray step (>15 nm/s). Together, these two rapid processes enable an overall throughput comparable to solution-based methods. However, VTD-grown PbI 2 films display a characteristic island-like morphology, arising from a “gas–particle–film” growth pathway. By adjusting carrier gas temperature and flow rate, the nucleation environment and resultant particle size distribution were effectively controlled, thereby tuning the final film microstructure. Guided by this mechanistic understanding, we achieved a power conversion efficiency (PCE) exceeding 14%, surpassing previously reported VTD-prepared devices. The optimized devices showed moderate stability, retaining 80% of their initial efficiency after 400 h of thermal aging at 60 °C and after 600 h of continuous light soaking in nitrogen.