In Operando Locally-Resolved Photophysics in Perovskite Solar Cells by Correlation Clustering Imaging.

Area of Science:

• Materials Science
• Photovoltaics
• Solid-State Physics

Background:

• Metal halide perovskites offer high solar cell efficiencies but suffer from instability due to ion migration.
• This instability causes material degradation and defect formation, hindering commercialization.

Purpose of the Study:

• To introduce Correlation Clustering Imaging (CLIM) as a novel technique to study perovskite dynamics.
• To visualize the polycrystalline structure and defect behavior in perovskite films and solar cells.

Main Methods:

• Utilizing wide-field fluorescence microscopy to detect local photoluminescence (PL) fluctuations.
• Applying CLIM to analyze PL variations in perovskite materials and devices under operating conditions.

Main Results:

• CLIM successfully visualized perovskite polycrystalline grain structures, correlating with electron microscopy.
• Identified a dominant metastable defect responsible for PL fluctuations.
• Observed significantly larger fluctuations and correlated regions (up to 10 µm) in solar cells compared to films (2 µm).

Conclusions:

• CLIM provides insights into carrier transport, ion migration, and recombination losses by analyzing PL fluctuations.
• The technique reveals functional dynamics in perovskite solar cells, linked to charge extraction channels.
• CLIM offers a non-invasive, operando method to understand luminescent materials and devices.