Proton Irradiation Reconfigures Temperature-Dependent Emissive Heterogeneity in Wide-Bandgap All-Inorganic CsPbI2Br Perovskite Solar Cells

Abstract Wide-bandgap metal-halide perovskites are attractive for space power due to their high open-circuit voltages and compatibility with tandem device architectures, but their response to orbital stressors remains under-explored. Here, we show that 1.86 eV all-inorganic CsPbI2Br perovskite solar cells (PSCs) develop an emissive heterogeneity when cooled to 193 K (–80 °C), marked by the emergence of distinctly bright, blue-shifted emission centers near 1.89 eV. This low-temperature blue shift is accompanied by an increased open-circuit voltage but reduced charge extraction, as revealed by operando current–voltage measurements. As the operating temperature increases to 373 K (+100 °C), the spatial emissive contrast becomes less pronounced and emission is quenched, yielding a comparatively more spatially uniform emission landscape and improved charge extraction. Irradiation of these n-i-p PSCs with 1.0 MeV protons at a fluence of 5 × 1013 cm–2 reconfigures the emissive heterogeneity, with enhanced spatial contrast at 193 K including linewidth narrowing of certain emissive components and persistent emissive features at warmer temperatures. These results suggest that proton irradiation modifies the emissive landscape in ways not fully captured by room-temperature device metrics alone. More broadly, we demonstrate that the apparent radiation tolerance of wide-bandgap PSCs at room temperature can mask the underlying heterogeneity that becomes significantly more visible under space-relevant thermal extremes.