Perovskite photovoltaics combine high power-conversion efficiencies with low weight, mechanical flexibility, and bandgap tunability, making them highly attractive for both terrestrial energy generation and next-generation space power systems. However, their practical deployment is still limited by stability losses that depend strongly on the operating environment. In this contribution, we identify the dominant degradation pathways in perovskite-based single-junction and tandem solar cells and discuss how these mechanisms evolve from standard Earth-based operation to the extreme conditions relevant for space applications.

Therefore, we focus on ion-related instabilities as a central origin of performance losses. In particular, we show how mobile ions can induce operational degradation and current losses, even in highly efficient passivated devices, where interfacial treatments improve open-circuit voltage and fill factor but can also introduce new instability pathways under working conditions. Our recent works further show that even minor halide segregation is closely coupled to ionic loss processes and strongly affects the evolution of device performance over time, making it one of the main factors limiting the energy–lifetime product of perovskite tandems.

We extend this analysis toward space photovoltaics, motivated by our satellite demonstration efforts. Space deployment exposes devices to extreme environments, including low temperatures, low-intensity illumination, and repeated temperature cycling during orbital operation. Under such conditions, all-perovskite tandems can experience severe performance constraints, especially in the wide-bandgap top cell, where low-temperature operation can enhance demixing, intensify ion-related losses, and induce subcell current mismatch. These effects are particularly critical in monolithic tandems, where degradation in one subcell directly compromises the performance of the full device stack. On the other hand, ionic mobility enables self-healing and repair mechanisms, resulting in high resilience to high-energy proton irradiation. Lastly, I would like to highlight the relevance of mechanical reliability, especially for lightweight and flexible perovskite devices. Flexible architectures are highly promising for both portable terrestrial applications and space platforms because of their low mass and conformability. At the same time, bending, handling, launch-associated stress, and repeated deformation can generate mechanical damage such as microcracks, interfacial delamination, or electrode failure, strongly degrading performance.

Overall, I will provide an overview of the stability-limiting mechanisms in perovskite single-junction and tandem photovoltaics for Earth and space applications, which we are currently investigating. Beyond advanced understanding, linking halide segregation, mobile-ion dynamics, low-temperature and thermal-cycling effects, and mechanical damage in flexible devices, I will show mitigation strategies that significantly stabilize performance for the investigated stressors.