Photoinduced Structural Phase Transitions in Polyacene

TL;DR

This study investigates photoinduced structural phase transitions in polyacene, revealing a one-way optical switching between cis and trans isomers influenced by electron correlations and light intensity.

Contribution

It provides a detailed analysis of phase boundaries, optical spectra, and photoresponses of polyacene isomers using correlated and uncorrelated Hamiltonians, highlighting the one-way switching mechanism.

Findings

Weak light can induce transitions in uncorrelated electrons.

Correlated electrons require a threshold light intensity for transition.

Trans to cis conversion is feasible, reverse is limited.

Abstract

There exist two types of structural instability in polyacene: double bonds in a cis pattern and those in a trans pattern. They are isoenergetic but spectroscopically distinct. We demonstrate optical characterization and manipulation of Peierls-distorted polyacene employing both correlated and uncorrelated Hamiltonians. We clarify the phase boundaries of the cis- and trans-distorted isomers, elucidate their optical-conductivity spectra, and then explore their photoresponses. There occurs a photoinduced transformation in the polyacene structure, but it is one-way switching: The trans configuration is well convertible into the cis one, whereas the reverse conversion is much less feasible. Even the weakest light irradiation can cause a transition of uncorrelated electrons, while correlated electrons have a transition threshold against light irradiation.