Related Experiment Video
Updated: Aug 7, 2026

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Dimensionality-Dependent Exciton-Phonon Coupling in 2D and Quasi-2D Perovskites Revealed by Transient Infrared
Shaokuan Gong1, Pan Wang1, Yuling Huang1
1State Key Laboratory of Quantum Functional Materials, SUSTech Energy Institute for Carbon Neutrality, Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
None:
While the exceptional emission properties of two-dimensional Ruddlesden-Popper perovskites are fundamentally governed by exciton-phonon interactions, tracking these dynamic lattice couplings remains elusive due to the state-filling limitations of visible-spectrum spectroscopy. Herein, we utilize broadband mid-infrared transient absorption spectroscopy to directly probe the intraexcitonic transitions and dynamic lattice reorganizations across a dimensionality series (n = 1, 2, and 4) of phenethylammonium (PEA)-based perovskites. We observe a profound, dimensionality-driven tuning of the microscopic coupling mechanism. In the extreme confinement limit (n = 1), intense structural distortion washes out discrete transitions, yielding a broad continuum indicative of rapid self-trapping. Relaxing this confinement (n = 2) unveils beautifully resolved Franck-Condon progressions driven by ≈10 meV inorganic Pb-I optical phonons. By fitting this progression, we extract a Huang-Rhys factor of S ≈ 0.57, quantitatively confirming an intermediate coupling regime that prevents deep self-trapping. Further relaxation (n = 4) shifts the dominant interaction to higher-energy (≈33 meV) organic cation modes. This work demonstrates that structural dimensionality provides a direct lever to engineer the specific exciton-phonon bath, offering the fundamental physical blueprint required to optimize emission lineshapes for high-efficiency perovskite optoelectronics.
Related Concept Videos
IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
According to Hooke's law, the vibrational frequency is directly proportional to the...
IR Absorption Frequency: Delocalization
In IR spectroscopy,...
UV–Vis Spectroscopy: Molecular Electronic Transitions
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in the...

