Charge Carrier Relaxation in Colloidal FAPbI₃ Nanostructures Using Global Analysis

Area of Science:

• Materials Science
• Condensed Matter Physics
• Photovoltaics

Background:

• Hybrid lead iodide perovskites exhibit unique optoelectronic properties.
• Understanding charge carrier dynamics is crucial for device efficiency.
• Colloidal nanostructures offer tunable properties for advanced applications.

Purpose of the Study:

• To investigate hot charge carrier relaxation dynamics in FAPbI3 perovskite nanostructures.
• To compare conventional analysis with a global analysis method for accuracy.
• To elucidate the influence of hot phonon bottleneck and Auger heating on carrier cooling.

Main Methods:

• Femtosecond transient absorption (TA) spectroscopy.
• Conventional analysis of carrier temperature (T) via spectral fitting.
• Global analysis modeling spectral lineshape evolution with a kinetic model.

Main Results:

• The global analysis method provides more accurate charge carrier relaxation dynamics.
• Hot phonon bottleneck effect increases cooling time to ~1 ps in nanoplates and nanocrystals at high fluence.
• Auger heating further extends relaxation times to tens and hundreds of picoseconds.
• Simultaneous analysis of spectral lineshape and amplitude is essential to disentangle these effects.

Conclusions:

• A global kinetic modeling approach offers superior accuracy for charge carrier relaxation studies.
• Hot phonon bottleneck and Auger heating are significant factors limiting carrier cooling in perovskite nanostructures.
• These findings are critical for optimizing perovskite-based optoelectronic devices.