Photoinduced cooperative charge transfer in low-dimensional organic crystals

The cooperative charge transfer among constructive molecules in organic crystals of tetrathiafulvalene-chloranil induced by the irradiation of a laser pulse with an 80-fs width are studied. It is shown that the photoinduced neutral-ionic phase transition is bidirectional and that the photoinjected localized excited states grow into the macroscopic metastable phase domain within 1 ns. The photoconverted fraction and the growth dynamics of the localized photoexcited species into the macroscopic domain are also dependent on the excitation intensity.