Ultrafast Excitonic Response in Two-Dimensional Hybrid Perovskites Driven by Intense Midinfrared Pulses

Area of Science:

• Materials Science
• Solid-State Physics
• Spectroscopy

Background:

• Two-dimensional organic-inorganic hybrid perovskites (2DHPs) exhibit quantum-well characteristics due to organic spacers.
• These spacers induce strong confinement, leading to tightly bound excitons with high binding energy.

Purpose of the Study:

• To investigate the interactions between organic spacer cations and the inorganic framework in 2DHPs.
• To understand the impact of organic spacers on exciton dynamics and energy dissipation.

Main Methods:

• Femtosecond pump-probe spectroscopy was employed.
• Direct vibrational pumping of organic spacers followed by visible-to-ultraviolet probing of excitonic resonances.

Main Results:

• Two temporal response regimes were observed: transient expansion of organic layers and lattice heating effects.
• Vibrational excitation enhanced biexciton emission, attributed to stronger exciton confinement and detrapping from defects.

Conclusions:

• Organic spacers significantly impact exciton properties in 2DHPs.
• Excited-state dynamics and vibrational energy dissipation pathways were elucidated in these materials.