Redox Cascade-Driven Structural Degradation Under Reverse Bias in All-Perovskite Tandem Solar Cells.

Area of Science:

• Materials Science
• Chemistry
• Energy Science

Background:

• All-perovskite tandem solar cells face instability issues under reverse bias, often due to current mismatch or shading.
• This instability leads to performance degradation and irreversible damage within the narrow-bandgap subcells.

Purpose of the Study:

• To elucidate the degradation mechanism of all-perovskite tandem solar cells under reverse bias.
• To develop a strategy to mitigate reverse bias-induced degradation and improve device stability.

Main Methods:

• Investigated the effect of sustained reverse bias on the narrow-bandgap subcells.
• Analyzed the redox reactions and ion migration processes under electrical stress.
• Introduced and tested a "multideck-fence" interfacial design.

Main Results:

• Sustained reverse bias triggers a redox-coupled lattice collapse via oxidation of iodide and tin, leading to ion migration and corrosion.
• The "multideck-fence" interface, combining an oxide diffusion barrier and dual-metal electrode, effectively halts this degradation.
• Achieved a power conversion efficiency of 29.03% with over 30-fold improvement in reverse-bias endurance.

Conclusions:

• Reverse bias acts as a chemomechanical failure mode in perovskite solar cells, converting electrical stress into electrochemical damage.
• The developed interfacial design provides a mechanistic framework for creating bias-resilient perovskite solar cell architectures.