Ultrafast charge dynamics in organic one-dimensional Mott insulators

Abstract

Ultrafast charge dynamics in one-dimensional Mott insulators was investigated by femtosecond reflection spectroscopy on organic molecular compounds, K-tetracyanoquinodimethane (TCNQ), Rb-TCNQ, and bis(ethylenedithio)tetrathiafulvalene (ET)-difluorotetracyanoquinodimethane (F 2TCNQ). In K- and Rb-TCNQ, photocarriers are localized as polarons with ∼70 fs and recombine with a few ps. In ET-F 2TCNQ, photocarriers lead to a metallic state and decay with ∼200 fs. Such differences of the charge dynamics can be explained by taking account of the different magnitudes of the electron-lattice interactions in the three compounds.