Perovskite/CIGS Tandem Solar Cells with over 1000 h Operational Stability through Interconnection Stress Relief

Perovskite/CIGS thin-film tandem solar cells offer a promising solution for lightweight and cost-effective photovoltaic technologies. However, their practical deployment is hindered by unsatisfied long-term operational stability. In this study, we identify perovskite films deposited on smoothed CIGS substrates exhibit tensile stress, which weakens bonding interactions, induces chemical structural instability, lowers defect formation energy and ion migration activation energy, impeding long-term operation of tandem devices under photothermal stress. Rough CIGS substrates featured with corrugated surface morphology effectively alleviating harmful tensile stresses. As a result, photothermal tolerance and optoelectronic properties are enhanced in corresponding perovskite films. The monolithic perovskite/CIGS tandem devices achieve a certified stabilized efficiency exceeding 28%, along with a notably extended T₈₀ lifetime of 1123 h under maximum power point tracking with full-spectrum AM 1.5G illumination. Additionally, these devices demonstrate enhanced operational stability at an elevated temperature of 60 °C and under thermal cycling tests (from room temperature to 65 °C) in a N₂-filled glovebox. This work underscores the essential role of interconnection contact engineering in enhancing the long-term stability of perovskite-based devices.