Influence of hot spot heating on stability of large size perovskite solar module with a power conversion efficiency of ∼14%

Making perovskite solar cell technology commercially viable is facing a challenge that scaling-up of a small device always experiences a substantial reduction in power conversion efficiency (PCE). In this research, we adopted a volume expansion routine to scale-up from a 0.16 cm² laboratory-scale device to large size perovskite solar module (PSM) with a PCE loss of 8% and reached a certified PCE of 13.98%. The PCE of the PSM with Au electrode dropped about 40% of the initial efficiency after 16 days' storage, while the efficiency of PSM with Cu as counter electrode retained 90% of the initial after 30 days' storage. We also introduced hot spots heating (HSH) characterization method to investigate the stability of PSM. HSH reveals that Cu electrode greatly reduces numbers of hot spots and extent of temperature increase in a PSM compared with Au electrode. Therefore, counter electrode also plays an important role in the stability improvement of PSM.