Vacuum-processed perovskite PV devices. ITO coated glass substrates (15 Ω sq. -1 , Kintech) were employed for smallscale device fabrication (0.12 cm 2 active area) and 9.46 cm 2 devices. The substrates were cleaned with soap, deionized water, acetone and isopropanol in a sonication bath for 15 min at each step. Then, clean substrates were treated by UV-Ozone for 15 min, and transferred to a CreaPhys organic evaporator inside an MBraun N2 glovebox (O2 and H2O levels below 0.5 ppm). A spiro-TTB hole extraction layer (25 nm for small-scale and 60 nm for 9.46cm 2 device) was evaporated on the conductive substrates, followed by mixed cation lead mixed halide perovskite deposition. The substrates are transferred to a CreaPhys PEROvap evaporator inside an MBraun N2 glovebox (O2 and H2O levels below 0.5 ppm), where the perovskite deposition is conducted. The chamber was pumped down to a pressure of 1-310 -6 mbar for the deposition. We employed a specifically designed cooling system that maintains the evaporator walls, source shutters and shields at -20 °C throughout the entire process. This functionality minimises re-evaporation of the precursors and cross-contamination between sources, ensuring fine control over the evaporation rates and high reproducibility. To this end, FAI, PbI2 and CsBr were filled into three different crucibles, using fresh FAI and PbI2 powders for every deposition.