Exciton-phonon coupling in quasi-two-dimensional Ruddlesden-Popper perovskites: impact of a mixed-phase structure

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• Two-dimensional metal halide perovskites (2D MHPs) exhibit promising optical and electronic properties for optoelectronic and spintronic applications.
• Understanding exciton-phonon scattering is crucial for optimizing the performance of 2D MHPs.

Purpose of the Study:

• To systematically investigate the temperature-dependent photoluminescence (PL) of 2D Ruddlesden-Popper (RP) perovskites.
• To elucidate the influence of exciton-phonon scattering on the optoelectronic properties of different 2D phases (n=1-4).

Main Methods:

• Micro-photoluminescence (PL) spectroscopy was employed to study (C6H7SNH3)2(CH3NH3)nPb(n+1)I(3n+1) for n=1-4.
• Temperature-dependent measurements were conducted to analyze changes in optical band gap and exciton dynamics.

Main Results:

• The optical band gap of each 2D phase varies with temperature due to lattice expansion and exciton-phonon interactions.
• Exciton-phonon interaction strength increases with the number of inorganic layers (n), attributed to lattice mismatch and disorder.
• Exciton-phonon coupling and binding energies show distinct behaviors across different phases, influenced by the local exciton environment.

Conclusions:

• Exciton-phonon scattering significantly impacts the optoelectronic properties of 2D RP perovskites.
• The layer number (n) plays a critical role in modulating exciton-phonon interactions and their effects.
• Findings provide guidance for enhancing the efficiency of 2D-RP mixed-phase perovskite devices.