Investigating the Mechanism behind the Degradation of Cu-Based n-i-p-Type PSC Modules

Area of Science:

• Materials Science
• Renewable Energy
• Electrochemistry

Background:

• Perovskite solar cells (PSCs) offer a promising renewable energy source.
• Commercial viability is hindered by long-term stability issues, especially with cost-effective copper electrodes.
• Understanding degradation mechanisms is crucial for improving device lifetime.

Purpose of the Study:

• To systematically investigate the degradation behavior of n-i-p structure PSC modules with copper electrodes under continuous illumination.
• To identify the primary failure sites and mechanisms.
• To develop an effective strategy for enhancing the operational stability of PSC modules.

Main Methods:

• Optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were used to analyze aged PSC modules.
• Bias-dependent studies (-2 to +4 V) were conducted to assess the impact of electrical bias on degradation.
• A bismuth (Bi) interlayer was introduced between MoO3 and Cu to evaluate its protective effect.

Main Results:

• The P3 interconnection region was identified as the primary failure site, exhibiting localized corrosion.
• A redistribution of copper (Cu) and iodide species was observed in aged devices.
• Forward bias significantly accelerated degradation, indicating a field-driven mechanism involving iodide migration and reaction with copper.

Conclusions:

• Lateral migration of iodide ions and subsequent electrochemical reactions with copper electrodes lead to corrosive product formation and failure.
• A thin bismuth interlayer effectively suppresses ion migration and interfacial reactions, significantly improving device stability.
• The developed interfacial strategy enhances the long-term operational stability of copper-based perovskite solar cell modules.