Coherent Band-Edge Oscillations and Dynamic LO Phonon Mode Splitting as Evidence for Polaronic Coupling in Perovskites

Abstract

The coherence of collective modes, such as phonons, and their modulation of the electronic states are long sought in complex systems, which is a cross-cutting issue in photovoltaics and quantum electronics. In photovoltaic cells and lasers based on metal halide perovskites, the presence of polaronic coupling, i.e., photocarriers dressed by the macroscopic motion of charged lattice, assisted by terahertz (THz) longitudinal optical (LO) phonons, has been intensely studied yet still debated. This may be key for explaining the remarkable properties of the perovskite materials, e.g., defect tolerance, long charge lifetimes and diffusion length. Here we use the intense single-cycle THz pulse with the peak electric field up to $E_{THz}=$1000\,kV/cm to drive coherent band-edge oscillations at room temperature in CH${}_3$NH${}_3$PbI${}_3$. We reveal the oscillatory behavior dominantly to a specific quantized lattice vibration mode at ${\omega }_{\mathrm{LO}}\sim$4 THz, being both dipole and momentum forbidden. THz-driven coherent dynamics exhibits distinguishing features: the room temperature coherent oscillations at ${\omega }_{\mathrm{LO}}$ longer than 1 ps in both single crystals and thin films; the {\em mode-selective} modulation of different band edge states assisted by electron-phonon ($e$-$ph$) interaction; {\em dynamic mode splitting} controlled by temperature due to entropy and anharmonicity of organic cations. Our results demonstrate intense THz-driven coherent band-edge modulation as a powerful probe of electron-lattice coupling phenomena and provide compelling implications for polaron correlations in perovskites.

References in corpus (14)

• Local polar fluctuations in lead halide perovskite crystals
• Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal and cubic phases of methylammonium lead iodide
• Dynamic disorder, phonon lifetimes, and the assignment of modes to the vibrational spectra of methylammonium lead halide perovskites
• Phonon coherences reveal the polaronic character of excitons in two-dimensional lead-halide perovskites
• Optical Phonons in Methylammonium Lead Halide Perovskites and Implications for Charge Transport
• Tetragonal CH3NH3PbI3 Is Ferroelectric
• Probing Femtosecond Lattice Displacement upon Photo-carrier generation in Lead Halide Perovskite
• Ultrafast Terahertz Conductivity Probes of Topologically Enhanced Surface Transport Driven by Mid-Infrared Laser Pulses in Bi${}_2$Se${}_3$
• Ultrafast observation of critical nematic fluctuations and giant magnetoelastic coupling in iron pnictides
• Ultrafast terahertz probes of interacting dark excitons in chirality-specific semiconducting single-walled carbon nanotubes
• Non-equilibrium Pair Breaking in Ba(Fe1-xCox)2As2 Superconductors: Evidence for Formation of Photo-Induced Excitonic Spin-Density-Wave State
• Competing Orders and Ultrafast Energy Transfer at the Quantum Limit in a Nb${}_3$Sn Superconductor Probed by Terahertz Electrodynamics
• Ultrafast Probes of Nonequilibrium Hole Spin Relaxation in Ferromagnetic Semiconductor GaMnAs
• Reversible modulation and ultrafast dynamics of THz resonances in strongly photoexcited metamaterials

Cited by in corpus (7)

• Ultrafast Control of Excitonic Rashba Fine Structure by Phonon Coherences in a Metal Halide Perovskite CH${}_3$NH${}_3$PbI${}_3$
• Extreme Terahertz Magnon Multiplication Induced by Resonant Magnetic Pulse Pairs
• Lightwave Terahertz Quantum Manipulation of Non-equilibrium Superconductor Phases and their Collective Modes
• Chirality manipulation of ultrafast phase switchings in a correlated CDW-Weyl semimetal
• Ab-initio Simulations of Coherent Phonon-Induced Pumping of Carriers in Zirconium Pentatelluride
• Strongly Anharmonic Organic Cation Vibrations in Hybrid Lead Halide Perovskite CH3NH3PbI3 on Electronic Ground State
• Coherent Transfer of Lattice Entropy via Extreme Nonlinear Phononics in Metal Halide Perovskites