Regulating crystallization kinetics in high-performance perovskites solar modules via vapor seed layer engineering

A CsPbBr 3 seed-assisted strategy was employed to achieve high-quality, large-area perovskite films via vacuum evaporation, aiming to facilitate industrial applications. The crystallization process of the perovskite films during annealing was monitored using in-situ GIWAXS. The seed layer provided nucleation sites that enhanced perovskite film quality promoting large grain sizes through modifying PbI 2 and improved the interface between the NiO x layer and the perovskite film. Consequently, large-area perovskite solar modules (PSMs) with a high-power conversion efficiency (PCE) of 20.02% and excellent stability were successfully fabricated. • CsPbBr 3 seed layers improve α-FAPbI 3 perovskite film crystallinity, grain size, reduce defects, and enhance material quality. • In situ GIWAXS shows that CsPbBr 3 seed layers extend crystallization, aiding the δ-to-α phase transition. • CsPbBr 3 seed layers improve NiOx conductivity, reduce charge recombination, and optimize energy levels. • Using a vapor-blade coating with CsPbBr 3 seed layers achieves 20.02% efficiency in large-area solar modules (61.56 cm 2 ). Large-area fabrication of α-FAPbI 3 perovskite solar modules (PSMs) faces challenges in achieving uniform crystallinity and minimizing grain boundary defects. Herenin, a CsPbBr 3 seed layer was introduced onto the NiOx hole transport layer (HTL) via vacuum evaporation prior to perovskite film deposition using a vapor-blade coating method. Synchrotron-based in situ GIWAXS analysis revealed that the CsPbBr 3 seed layer effectively modulates the crystallization kinetics of PbI 2 , facilitating the transition from δ-phase to α-phase perovskite and yielding films with superior crystallinity, grain size, and structural orientation. This seed layer also enhances the conductivity of NiOx, improves charge transport efficiency, and reduces recombination losses. As a result, large-area PSMs (active area: 61.56 cm 2 ) incorporating the CsPbBr 3 seed layer achieved a power conversion efficiency (PCE) of 20.02 %, compared to 17.62 % for pristine devices. Additionally, these encapsulated modules exhibited excellent ambient stability, maintaining over 80 % of their initial performance after 1100 h under 60 % relative humidity. This study highlights the potential of CsPbBr 3 seed layer engineering as a scalable and effective strategy for industrial production of high-efficiency, stable perovskite solar modules.