Electric field driven polaron transport beyond the harmonic approximation in one-dimensional crystal lattices: From conventional polarons to supersonic solectrons
Phys. Rev. B 113, 184303 – Published 5 May, 2026
DOI: https://doi.org/10.1103/1q4n-jtvb
Abstract
We investigate polaron dynamics in anharmonic one-dimensional crystal lattices under external electric fields, uncovering a transition from conventional polaron transport to the emergence of supersonic solectrons: electron and lattice soliton composite quasiparticles. Using a mixed quantum-classical approach that combines quantum electron evolution with classical anharmonic lattice dynamics, hence nonlinear elasticity, described by a Morse potential, we identify three distinct electric field driven transport regimes: (i) Under weak fields, subsonic polarons in anharmonic lattices accelerate continuously into stable supersonic solectrons, unlike in harmonic systems where polarons remain subsonic. (ii) At intermediate fields, Bloch oscillations generate supersonic polarons at Brillouin zone boundaries, which further accelerate in anharmonic lattices but decelerate asymptotically toward the sound speed in harmonic systems. (iii) In moderately high fields, polarons nucleated at Brillouin zone centers accelerate supersonically only in anharmonic lattices, while harmonic polarons stay subsonic. Solectrons exhibit exceptional stability against scattering, maintaining coherent propagation where conventional polarons dissociate. The formation dynamics, governed by electron-phonon coupling strength, initial wave-packet width, and field intensity, reveal optimal parameter ranges for stable high-velocity transport. This provides transformative design principles for enhancing charge carrier mobility in organic electronic materials through intentional exploitation of anharmonicity.
