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Coherent band-edge oscillations and dynamic longitudinal-optical phonon mode splitting as evidence for polarons in perovskites
- Source :
- Physical Review B. 101
- Publication Year :
- 2020
- Publisher :
- American Physical Society (APS), 2020.
-
Abstract
- The coherence of collective modes, such as phonons and polarons, and their modulation of electronic states is long sought in complex systems, which is a crosscutting issue in photovoltaics and quantum electronics. In photovoltaic cells and lasers based on metal halide perovskites, the presence of polarons, i.e., photocarriers dressed by the macroscopic motion of charged lattice, assisted by terahertz (THz) longitudinal-optical (LO) phonons, has been intensely studied yet is still debated. This may be key for explaining the remarkable properties of the perovskite materials, e.g., defect tolerance, long charge lifetimes, and diffusion lengths. Here we use the intense single-cycle THz pulse with peak electric field up to ${E}_{\mathrm{THz}}=1000$ kV/cm to drive coherent polaronic band-edge oscillations at room temperature in ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbI}}_{3}\phantom{\rule{4pt}{0ex}}({\mathrm{MAPbI}}_{3})$. We reveal the oscillatory behavior is dominated by a specific quantized lattice vibration mode at ${\ensuremath{\omega}}_{\mathrm{LO}}\ensuremath{\sim}4\phantom{\rule{0.16em}{0ex}}\mathrm{THz}$, which is both dipole and momentum forbidden. THz-driven coherent polaron dynamics exhibits distinguishing features: room temperature coherent oscillations at ${\ensuremath{\omega}}_{\mathrm{LO}}$ longer than 1 ps in both single crystals and thin films, mode-selective modulation of different band-edge states assisted by electron-phonon interaction, and dynamic mode splitting at low temperature due to entropy and anharmonicity of organic cations. Our results demonstrate intense THz-driven coherent band-edge modulation is a powerful probe of electron-lattice coupling phenomena and polaronic quantum control in perovskites.
- Subjects :
- Physics
Quantum optics
Condensed matter physics
Phonon
Terahertz radiation
Anharmonicity
02 engineering and technology
021001 nanoscience & nanotechnology
Polaron
7. Clean energy
01 natural sciences
Dipole
Electric field
0103 physical sciences
010306 general physics
0210 nano-technology
Perovskite (structure)
Subjects
Details
- ISSN :
- 24699969 and 24699950
- Volume :
- 101
- Database :
- OpenAIRE
- Journal :
- Physical Review B
- Accession number :
- edsair.doi...........5bfbc0bfb6081d00c152bbb124e5e2dc