Optical Tuning of Wigner Lattice in Conducting Polymer Nanowires

Abstract

The well‐known characteristics such as switching transition of resistivity of charge density wave (CDW) can be observed in soft materials such as carbon nanotubes and conducting polymer nanowires due to Wigner lattice (WL) formation when long‐range Coulomb repulsion dominates over kinetic energy of charge carriers in confined geometry. Herein, it is shown that CDW energy‐gap and associated 1D WL parameters in polypyrrole nanowires depend on charge‐carrier (bipolarons) density, which can be tuned continuously with photoexcitation. Observed linear dependence of CDW energy‐gap with charge‐carrier density provides evidence of the WL formation in these conducting polymer nanowires. The observation is consistent with earlier findings of linear dependence of energy‐gap with lattice parameter, which can be tuned by pressure or substitution of ions in conventional CDW materials.