Spatially Resolved Carrier Dynamics at MAPbBr₃ Single Crystal-Electrode Interface

Area of Science:

• Materials Science
• Solid-State Physics
• Electrochemistry

Background:

• Organic-inorganic halide perovskites (OIHPs) show promise for solar cells and detectors.
• Coupling between electronic and ionic charge carrier dynamics in OIHPs is poorly understood.
• Existing methods lack the resolution to study interface phenomena at relevant scales.

Purpose of the Study:

• To investigate charge carrier dynamics at the methylammonium lead tribromide (MAPbBr3) single crystal-gold electrode interface.
• To spatially visualize temporal dynamics of electric fields and charge carriers.
• To elucidate mechanisms responsible for current-voltage hysteresis in OIHP devices.

Main Methods:

• Implementation of Kelvin probe force microscopy (KPFM) for charge carrier dynamics.
• Time-resolved KPFM mapping to visualize electric field and charge distribution.
• Study of bias-assisted charge dynamics under illuminated and dark conditions.

Main Results:

• Demonstrated interplay of charge injection, recombination, and ion migration at the interface.
• Identified unbalanced charge dynamics under bias, explaining current-voltage hysteresis.
• Observed wider space charge region under illumination due to negative charge accumulation, screening the electric field and reducing charge extraction.

Conclusions:

• Interface phenomena significantly impact OIHP device performance.
• Understanding charge carrier dynamics is key to optimizing devices.
• Interfacial engineering offers a route to enhance OIHP device performance without bulk material modification.