Scalable Coating of Spatially Uniform WBG Perovskites via Inhibiting SAM Aggregation for Flexible All-Perovskite Tandem Modules.

Flexible all-perovskite tandem solar modules offer high power-to-weight ratios, making them promising for applications in flexible electronics and aerospace. However, their fabrication over large area remains challenging due to difficulties in achieving uniform coating and controlled crystallization of perovskites using scalable meniscus-based deposition methods, partly arising from poor ink-substrate adhesion. Herein, perovskite ink wettability is improved by utilizing nickel oxide (NiO x ) interlayer to suppress the aggregation of self-assembled molecules (SAMs) and enhance the hydrophilicity of the SAM layer. As a result, wide-bandgap (WBG) perovskite films were deposited onto large-area flexible substrates via doctor-blade coating, exhibiting excellent spatial uniformity and achieving minor pixel-to-pixel variation in power-conversion efficiencies (PCEs) on cell scale. The best-performing flexible WBG perovskite solar cells and mini-modules achieve PCEs of 16.7% and 13.3%, respectively. Furthermore, when integrated with a blade-coated narrow-bandgap perovskite subcell, this strategy enables the fabrication of flexible all-perovskite tandem solar cell with a PCE of 23.3%. An efficiency exceeding 20% is also demonstrated for flexible all-perovskite tandem mini-modules over an aperture area of 10.8 cm2. This study provides important insights into the regulation of SAM growth and establishes a foundation for the development of high-efficiency flexible all-perovskite tandem solar modules.