Printable High‐Efficiency and Stable FAPbBr3 Perovskite Solar Cells for Multifunctional Building‐Integrated Photovoltaics

Perovskite solar cells (PSCs) show great promise for next‐generation building‐integrated photovoltaic (BIPV) applications because of their abundance of raw materials, adjustable transparency, and cost‐effective printable processing. Owing to the complex perovskite nucleation and growth control, the fabrication of large‐area perovskite films for high‐performance printed PSCs is still under active investigation. Herein, the study proposes an intermediate‐phase‐transition‐assisted one‐step blade coating for an intrinsic transparent formamidinium lead bromide (FAPbBr3) perovskite film. The intermediate complex optimizes the crystal growth path of FAPbBr3, resulting in a large‐area, homogeneous, and dense absorber film. A champion efficiency of 10.86% with high open‐circuit voltage up to 1.57 V is obtained with a simplified device architecture of glass/FTO/SnO2/FAPbBr3/carbon. Moreover, the unencapsulated devices maintain 90% of their initial power conversion efficiency after aging at 75 °C for 1000 h in ambient air, and 96% after maximum power point tracking for 500 h. The printed semitransparent PSCs, with average visible light transmittance over 45%, demonstrate high efficiencies for both small devices (8.6%) and 10 × 10 cm2 modules (5.55%). Finally, the ability to customize the color, transparency, and thermal insulation properties of FAPbBr3 PSCs makes them high prospects as multifunctional BIPVs. An in situ intermediate phase transition‐controlled blade‐coating method for FAPbBr3 perovskite solar cells is introduced, which obtains a high power conversion efficiency (PCE) of 10.86% based on hole transport layer‐free structures of glass/FTO/SnO2/FAPbBr3/carbon. Semitransparent devices are fabricated and obtain high PCE of 8.61% at average visible light transmittance (AVT) = 45% and PCE of 5.55% at AVT = 53% for small devices and 10 × 10 cm2 modules, respectively.