Coherent Transfer of Lattice Entropy via Extreme Nonlinear Phononics in Metal Halide Perovskites

An illustration of a nonlinear entropy-transfer pathway driven by the strong THz-pulse radiation.
An illustration of a nonlinear entropy-transfer pathway driven by the strong THz-pulse radiation. The pathway is delineated
through three representative phonon modes from 2.91 THz to 0.51 THz and then reverting back to 0.91 THz.

Scientific Achievement

The phonon dynamics of methylammonium lead iodide are explored with time-resolved terahertz spectroscopy and first-principles molecular dynamics simulations, revealing a bidirectional entropy transfer mechanism that may inform the design of perovskite active layers in solar cells and optoelectronic devices.

Significance and Impact

This discovery sheds light on a long-standing hypothesis in metal halide perovskites, suggesting that unique entropy transfer pathways are key to the remarkable and enigmatic properties observed in MHP-based photovoltaics, solar cells, and lasers.

Research Details

  • Terahertz quantum beat spectroscopy measurement reveals vibronic (exciton-phonon) coupling with a unique temporal evolution of diverse phonon modes
  • First-principles molecular quantum dynamics simulations identify the salient roles of the initial phonon modes in shaping the entropy evolution. 

Z. Liu ,Y. Shi, T. Jiang, L. Luo , C. Huang, M. Mootz , Z. Song, Y. Yan, Y. Yao, J. Zhao, and J. Wang, PRX Energy 3, 023009 (2024). https://doi.org/10.1103/PRXEnergy.3.023009