Anomalous Electroluminescence Characteristics of Perovskite Modules

Area of Science:

• Materials Science
• Photovoltaics
• Device Physics

Background:

• Spatially resolved photoluminescence (PL) and electroluminescence (EL) imaging are vital for assessing photovoltaic (PV) device performance and stability.
• Perovskite solar modules (PSMs) present unique challenges for EL/PL imaging due to complex interfacial phenomena.

Purpose of the Study:

• To investigate the discrepancy between electrical performance and EL imaging in PSMs.
• To identify the root cause of EL mismatch in perovskite solar cells.
• To develop a method for aligning EL imaging with actual device performance.

Main Methods:

• Application of reverse bias voltage to PSMs and monitoring of EL changes.
• Cross-sectional Kelvin probe force microscopy (KPFM) to analyze interfacial potential.
• Development and application of a mild reverse current recovery method.

Main Results:

• Reverse bias increased EL brightness, indicating prolonged carrier lifetime and transport length.
• KPFM revealed potential increases at the electron-transport layer (ETL)/perovskite interface, suggesting filled hole traps.
• The proposed reverse current recovery method successfully aligned EL images with cell performance without efficiency loss.

Conclusions:

• Defective ETL/perovskite interfaces contribute to EL imaging discrepancies in PSMs.
• A mild reverse current recovery method can correct EL mismatch, ensuring accurate performance assessment.
• Caution is needed when using EL imaging for spatial homogeneity monitoring in industrial PSM production.