LAUSR

Realizing photoactive and thermodynamically stable all‐inorganic perovskite solar cells (PSCs) remains a challenging task within halide perovskite photovoltaic (PV) research. Here, a dual strategy for realizing efficient inorganic mixed halide perovskite PV devices based on a terbium‐doped solar absorber, that is, CsPb1−xTbxI2Br, is reported, which undertakes a bulk and surface passivation treatment in the form of CsPb1−xTbxI2Br quantum dots, to maintain a photoactive γ‐phase under ambient conditions and with significantly improved operational stability. Devices fabricated from these air‐processed perovskite thin films exhibit an air‐stable power conversion efficiency (PCE) that reaches 17.51% (small‐area devices) with negligible hysteresis and maintains >90% of the initial efficiency when operating for 600 h under harsh environmental conditions, stemming from the combined effects of the dual‐protection strategy. This approach is further examined within large‐area PSC modules (19.8 cm2 active area) to realize 10.94% PCE and >30 days ambient stability, as well as within low‐bandgap γ‐CsPb0.95Tb0.05I2.5Br0.5 (Eg = 1.73 eV) materials, yielding 19.01% (18.43% certified) PCE.