Perovskite solar module upscaling relies on P1-P2-P3 laser scribing process to achieve efficient interconnection  and efficient devices. However, the laser can introduce local damage and accelerate degradation in the already sensitive perovskite absorbers. Consequently, the scribe regions themselves may become critical sites governing long-term module stability.

In this work, laser-scribed regions in p-i-n perovskite mini-modules were investigated before and after 337h of ISOS-L3 ageing under maximum power point tracking (MPPT). The electrical performances (IV curves) of the cells constituting the module as well as  SEM morphological studies and spatially-resolved photoluminescence (PL) spectra are measured. Indeed, the energy positions and the intensities of the PL peaks are intimately related to the composition and the crystalline quality of the perovskites layers, giving information about their degradation. Some EDX mapping measurements have been performed to have more detailed insights in the degradation mechanisms.

From the analysis of the PL measurements at the three different scribes, P1-P2-P3 and their interscribe area,  the P1 scribing seems to be a  major source of degradation.  After ageing the whole P1 scribe area displayed PL peaks which were red-shifted compared the fresh (non-aged) module, and a ten-fold increase of the PL response has been observed. The increase of PL signal could potentially be explained by the 1 μm hill that emerged on the side of the P1 scribe after ageing. The hill was analyzed by EDX where asymmetric concentration changes were observed at the different sides of the hill. Moreover, a SEM cross section of the P1 scribing revealed that the perovskite had expanded from a densely packed layer to a more porous type with internal cavities. This could support the theory of potential gaseous I₂ in the P1 due to poor crystallization that then is more prone to defects under operation [1]

The P1 PL-response did also have a direct correlation to the other scribe PL signals where secondary peaks emerge behind red-shifted P1 scribes towards P2-P3, indicating a potential correlation between the P1 PL-shift and the P2-P3 degradation.

In conclusion, the P1 scribe seems to be majorly affected from the ageing process comparing to the P2 and P3 ones, due to poor crystallization. The correlation between P1 peak shift and following change of P2-P3 seems to indicate that the P1 impacts the remaining scribe degradation.