Understanding the Interfaces between Triple-Cation Perovskite and Electron or Hole Transporting Material

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Efficient solar cells are crucial for renewable energy.
• Triple-cation perovskites offer promising photovoltaic properties.
• Understanding interfacial charge dynamics is key to improving solar cell performance.

Purpose of the Study:

• To investigate the properties of triple-cation perovskite solar cells.
• To compare devices fabricated under drybox and ambient conditions.
• To analyze charge dynamics at the titania and spiro-OMeTAD interfaces.

Main Methods:

• Fabrication of perovskite solar cells under controlled and ambient conditions.
• Morphological studies using unreacted lead iodide (PbI2) phase analysis.
• Spectroscopic analysis including stationary emission and transient bleach peaks.
• Time-resolved techniques (femtoseconds to seconds) to study charge dynamics.
• Ideality factor analysis with varying dimethyl sulfoxide (DMSO) content.

Main Results:

• Higher unreacted PbI2 content near the titania interface.
• Distinct long-wavelength emission features near the titania interface.
• Faster population decay at the titania interface for ambient-prepared cells.
• Increased hole injection rate and photocurrent in drybox-prepared devices.
• Slower charge recombination at the titania interface compared to the spiro-OMeTAD interface.
• Ideality factor increase with DMSO content suggests a shift from bulk to surface recombination.
• Non-uniform charge dynamics observed across the perovskite layer.

Conclusions:

• Charge dynamics are not uniform within triple-cation perovskite solar cells.
• Interfacial properties significantly influence charge carrier behavior and recombination.
• Fabrication conditions (drybox vs. ambient) impact device performance.
• Optimizing interfaces and understanding non-uniform charge dynamics are critical for enhancing solar cell efficiency.