Reliability enhancement of PVDF-HFP modified perovskite solar cells under synergistic space-relevant stress conditions

Abstract

Thermal stress represents a critical reliability bottleneck for perovskite solar cells (PSCs) in space environments, where sustained high temperatures can accelerate irreversible degradation. Beyond isolated thermal effects, PSCs in orbit experience synergistic stressors including vacuum, illumination, and elevated temperature. This study investigates the stability of p-i-n PSCs under combined vacuum + light (V + L) and vacuum + heat (V + H) conditions, focusing on thermally activated interfacial failure and polymer-based mitigation. Devices are evaluated under two temperature regimes: moderate (85 and 100 °C) and extreme (115 and 130 °C) V + H stress, together with prolonged V + L exposure. The results show that degradation is dominated by interface-driven non-radiative recombination rather than bulk absorber failure, with ΔV3 increase, QFLS reduction, and interface-specific pseudo-PCE loss, identifying the perovskite/PCBM as the primary weak point under V + H stress. Incorporation of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) into the perovskite layer effectively suppresses defect generation, preserves microstructural integrity, and improves charge-extraction stability, leading to enhanced performance retention. Hazard-based Weibull-Arrhenius analysis confirms extended characteristic lifetimes for PVDF-HFP devices at moderate temperatures, with a higher activation energy (0.95 eV vs 0.83 eV) indicating a modified degradation pathway. Room-temperature lifetime is further predicted using a graphical extrapolation method, yielding significantly extended projected operational lifetimes for polymer-modified devices. These findings establish a reliability enhancement of the PVDF-HFP-modified devices under synergetic space-relevant stress.