Neutron Resilience of Flexible Perovskite Solar Cells Using PTAA-Derived Hole Transport Layers

Flexible perovskite solar cells hold promise of being an enabling technology for space missions: by reducing the encumbrance and weight of the payload's power system, launch costs can be minimized. The increased interest, however, must be accompanied by thorough testing under a broad range of space-related sources of degradation and investigation of their effects on the layer stack. In this work, the resilience against atmospheric neutron radiation (<800 MeV) of flexible devices is studied, using two different hole transporting materials: a commercial PTAA and a PTAA-based in-house synthesized polymer. After 5 10⁹ particles/cm² irradiation, 380 times higher than the yearly fast neutron fluence in low Earth orbit, the devices show good stability, with efficiency losses below 20%. Further investigation by light intensity-dependent JV scans, hyperspectral photoluminescence microscopy, X-ray diffraction, X-ray reflectivity, and atomic force microscopy reveals that the neutron radiation mainly affects the perovskite/hole transport layer interface, to a different extent depending on the material. This work confirms that accelerated stress testing is an important tool to determine the feasibility of this technology for space applications and provides insights on the damages caused by atmospheric neutrons which will help inform future decisions for the fabrication of space-resilient flexible perovskite solar cells.