Higher Order Polaronic-Exciton Recombination in Two-Dimensional Dion-Jacobson-Type Perovskites.

Area of Science:

• Materials Science
• Solid-State Physics
• Photochemistry

Background:

• Non-radiative recombination is a critical factor in the performance of light-emitting materials.
• Understanding exciton dynamics in low-dimensional hybrid materials is essential for technological advancement.

Purpose of the Study:

• To investigate the dominant exciton recombination pathways in two-dimensional (2D) Dion-Jacobson (DJ) hybrid perovskites.
• To elucidate the electronic and structural factors governing ultrafast non-radiative recombination in these materials.

Main Methods:

• Studied two DJ perovskites with varying exciton-phonon coupling and polaronic character.
• Analyzed ultrafast (0.6-5 ps) biexcitonic Auger recombination rates.
• Investigated the relationship between recombination rates and material properties like dielectric confinement, lattice distortion, and exciton binding energy.

Main Results:

• The biexcitonic Auger process is the dominant recombination pathway in 2D DJ perovskites, occurring within picoseconds.
• Ultrafast non-radiative recombination is primarily governed by strong exciton-phonon coupling and dielectric confinement.
• Auger recombination was observed below the Mott density, establishing a lower bound of 1.3 × 10^19 cm^-3 for 2D DJ perovskites, significantly higher than in 3D perovskites.

Conclusions:

• 2D DJ perovskites exhibit intrinsically ultrafast higher-order recombination of polaronic-excitons.
• These materials possess unique excitonic properties distinct from conventional 3D systems.
• Exciton-phonon coupling and dielectric confinement are key determinants of non-radiative recombination in these 2D perovskites.