Interlayer Charge Transport in 2D Lead Halide Perovskites from First Principles

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Two-dimensional (2D) lead halide perovskites are promising materials for optoelectronic applications.
• Understanding charge transport mechanisms is crucial for device performance.
• Organic spacers play a key role in modulating electronic properties.

Purpose of the Study:

• To implement and apply a versatile projection-operator diabatization approach for calculating electronic coupling integrals.
• To model charge transport across organic spacers in 2D lead halide perovskites.
• To investigate the influence of structural distortions and dynamic disorder on charge transfer rates.

Main Methods:

• Projection-operator diabatization approach.
• Calculation of electronic coupling integrals.
• Modeling of charge transport in layered periodic systems.
• Analysis of out-of-plane charge transfer rates and their dependence on alkyl chain length.

Main Results:

• Charge transfer rates decay exponentially with increasing alkyl chain length.
• Calculated rates range from nanoseconds to milliseconds, supporting a hopping mechanism.
• Charge carriers strongly couple to Pb-I framework distortions.
• Inclusion of nonlocal dynamic disorder increases thermally averaged interlayer rates by orders of magnitude compared to static structures.

Conclusions:

• The implemented formalism provides comprehensive insight into the role of organic spacer cations in vertical transport.
• Dynamic disorder significantly enhances charge transfer rates in 2D lead halide perovskites.
• The approach can be extended to π-conjugated spacers for potentially faster charge transfer.